All of Edexcel BIOLOGY Paper 1 in 30 minutes - GCSE Science Revision

00:26:43
https://www.youtube.com/watch?v=7f1TY5BSfw8

Summary

TLDRThe video summarizes key concepts from Edexcel GCSE Biology Paper 1, aimed at higher-tier, foundation-tier, double combined, or triple separate students. It outlines fundamental topics including cell biology, genetics, natural selection, genetic modification, and health. Key elements such as eukaryotic vs. prokaryotic cells, enzyme function, diffusion, osmosis, the immune response, and the significance of genetic engineering in medicine are discussed. Additionally, the video covers aspects of non-communicable and communicable diseases, the importance of vaccines, and advances in drug development and monoclonal antibodies.

Takeaways

  • 🔬 Cells are fundamental units of life with distinct structures.
  • 🧬 Eukaryotic cells have a nucleus; prokaryotic cells do not.
  • ⚗️ Enzymes are specific biological catalysts that speed up reactions.
  • 🌊 Osmosis is critical for maintaining cell function and balance.
  • 🌱 Genetic modification enhances crop yields and nutrition.
  • 💉 Vaccines prepare the immune system for future infections.
  • 🦠 The immune system uses various mechanisms to combat pathogens.
  • 📈 Understanding natural selection is key to evolutionary biology.
  • ⚖️ Monoclonal antibodies target specific diseases effectively.
  • 🔄 Meiosis introduces genetic diversity in sexual reproduction.

Timeline

  • 00:00:00 - 00:05:00

    The video covers the main ideas from the Edexcel GCSE Biology Paper 1, focusing on topics crucial for higher-end and foundation-tier students, including cells, control, genetics, natural selection, health, and medicine. Need for a strong basic understanding of life that consists of cells is emphasized, including the differences between eukaryotic and prokaryotic cells and the functions of various cell organelles.

  • 00:05:00 - 00:10:00

    The session dives deeper into enzymes, their specific roles, and the importance of temperature and pH levels affecting enzyme activity. The lock-and-key model explains the specificity of enzyme action, while practical experiments illustrate how to determine optimum conditions for enzyme efficiency through observable starch breakdown.

  • 00:10:00 - 00:15:00

    Discussion on transport mechanisms in cells follows, distinguishing between diffusion, osmosis, and active transport, highlighting how substances move across membranes. Osmosis is defined specifically for water movement, while practical activities demonstrate how to quantify changes in cell mass due to osmotic effects in varying sugar solutions.

  • 00:15:00 - 00:20:00

    The focus shifts to cell division through mitosis and meiosis, outlining genetic material duplication leading to specialized cell functions. The importance of stem cells and their potential applications in medical treatments is mentioned, along with ethical considerations for cloning, emphasizing the role of stem cells in growth and repair.

  • 00:20:00 - 00:26:43

    Lastly, the video touches on evolution, genetic variation, and the implications of selective breeding versus genetic modification. It discusses the Human Genome Project, outlining how genetics play a vital role in diseases along with the significance of drugs and monoclonal antibodies in medical research and treatments, underscoring their applications and potential side effects.

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Mind Map

Video Q&A

  • What are the main topics covered in Edexcel GCSE Biology Paper 1?

    Key topics include cells and control, genetics, natural selection, genetic modification, health, disease, and medicines.

  • What is the difference between eukaryotic and prokaryotic cells?

    Eukaryotic cells have a nucleus that contains DNA, while prokaryotic cells do not have a nucleus and their DNA is found in plasmids.

  • What are the roles of enzymes in biological processes?

    Enzymes act as biological catalysts that speed up chemical reactions, and each enzyme is specific to its substrate.

  • What is the purpose of osmosis in cells?

    Osmosis is the diffusion of water across a semi-permeable membrane, which helps maintain cell turgidity and balance concentrations.

  • How do genetic modifications benefit agriculture?

    Genetic modifications can enhance crop yields, resistance to diseases, and nutritional value.

  • What is the purpose of vaccines?

    Vaccines introduce a harmless form of a pathogen to stimulate the immune response, allowing the body to produce memory cells for future protection.

  • What differentiates monoclonal antibodies from polyclonal antibodies?

    Monoclonal antibodies are produced from a single clone of cells, targeting a specific antigen, while polyclonal antibodies are derived from multiple clones.

  • How does the body defend against pathogens?

    The immune system uses physical barriers, white blood cells, and antibodies to combat invading pathogens.

  • What is the process of natural selection?

    Natural selection occurs when individuals with traits better suited to their environment survive and reproduce, leading to evolutionary changes over time.

  • What is the role of meiosis in sexual reproduction?

    Meiosis produces gametes with half the chromosome number, allowing for genetic diversity in offspring during fertilization.

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  • 00:00:00
    let's see how quickly we can cover the
  • 00:00:01
    main ideas found in edexel GCSE biology
  • 00:00:04
    paper 1 this is good for higher end
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    Foundation Tier double combined or
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    triple separate that's topics 1 to five
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    key Concepts cells and control genetics
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    natural selection and genetic
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    modification and health disease and
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    medicines it's a mouthful isn't it I'll
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    tell you when some of the bigger
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    concepts are just for triple but not for
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    higher and Foundation tier because
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    there's not a lot of difference to be
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    honest we're going to be really moving
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    here so pause the video if you need a
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    bit more time to get your head around
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    something you see let's go all life
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    consists of cells we can see cells with
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    a normal light microscope and maybe the
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    nucleus but the subcellular structures
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    won't really be visible using an
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    electron microscope however allows us to
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    see far finer details so we can see an
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    image of the organel as such these
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    microscopes have a better resolving
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    power and a higher resolution we say we
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    can calculate the actual size of a cell
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    by knowing the magnification of the
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    microscope magnification is equal to
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    image size divided by object size
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    therefore rearranging this we can
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    measure me the size of the image then
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    divide by the magnification and that
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    gives us the actual cell size we put
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    them into two main groups eukaryotic
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    cells have a nucleus in which their DNA
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    is found that's your plant and animal
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    cells for example procaryotic cells
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    don't have a nucleus and their DNA is
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    found in a ring called a plasmid both
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    eukaryotic and procaryotic cells contain
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    similar organel or subcellular
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    structures the cell membrane keeps
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    everything inside the cell but they're
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    also semi-permeable which means they
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    allow certain substances to pass through
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    plant cells and most bacteria have an
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    extra cell wall made of cellulose
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    providing a rigid structure for them
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    cytoplasm is the liquid that makes up
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    the cell in which most chemical
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    reactions take place mitochondria is
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    where respiration takes place releasing
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    energy for the cell to function
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    ribosomes are where proteins are
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    assembled or synthesized plant cells
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    also contain chloroplasts which contain
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    chlorophyll where photosynthesis takes
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    place plant cells also contain a
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    permanent vacuo in which sap is stored
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    and enzymes are biological catalysts
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    some of which break down larger
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    molecules into smaller ones that can
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    then be absorbed by the Villi and your
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    small intestine into the bloodstream to
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    be transported to every part of your
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    body for example amalay is the enzyme
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    that breaks down starch into glucose
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    it's found in your small intestine and
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    saliva enzymes are specific that is they
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    only break down certain molecules for
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    example carbohydrases break down
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    carbohydrates into simple sugars amalay
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    is one of these proteases break down
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    proteins into amino acids and liases
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    break down lipids that's fats into
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    glycerol and fatty acids they're
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    specific because they work on a lock and
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    key principle the substrate for example
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    the starch binds to the enzyme's active
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    site we then call this a complex however
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    this can only happen if the substrate is
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    the right shape in order to fit the
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    active site in reality they're
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    incredibly complex shapes no pun
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    intended these shapes here are just to
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    represent them much like a locking key
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    it only works if they're the right shape
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    for each other the rate of enzyme
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    activity increases with temperature due
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    to to the molecules having more energy
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    that is until the active site changes
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    shape and so the substrate no longer
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    binds we say the enzyme has denatured
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    this maximum rate occurs at the optimum
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    temperature Optimum meaning best this is
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    similar for pH as well except it can Den
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    nature too high or too low PH the
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    Practical on this involves mixing amalay
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    with starch at different temperatures or
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    with different pH buffer Solutions once
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    mixed we start timing then every 10
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    seconds we remove a couple of drops and
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    put in a spot in tile dimple with I in
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    to begin with the iodine will turn black
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    due to the still being starch present
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    but eventually it will stay orange
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    showing that all of the starch has been
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    broken down calculate the time taken to
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    do that then plot these times against pH
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    or temperature draw a curved line of
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    best fit and the lowest point is where
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    the starch would have taken the shortest
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    time to be broken down that's the
  • 00:03:49
    optimum temperature or pH however in
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    true biology fashion we're technically
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    not allowed to interpolate between
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    points for some reason so we must only
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    say that the optimum pH or temperature
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    is between the two lowest points shrug
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    food test allow us to identify what
  • 00:04:04
    nutrients are in our grub iodine turns
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    from Orange to Black in the presence of
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    starch like we just saw Benedict
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    solution turns from Blue to Orange in
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    the presence of sugars bir's reagent
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    turns from Blue to purple with proteins
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    cold ethanol will go cloudy with lipids
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    that is fats diffusion is the movement
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    of molecules or particles from an area
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    of high concentration to an area of low
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    concentration we say they move down the
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    con concentration gradient like a ball
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    just rolling down a hill it'll do it by
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    itself this doesn't require any energy
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    input so we say it's passive this will
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    happen across a semi-permeable membrane
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    if the holes are large enough for the
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    molecules to move through for example
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    water can pass through but glucose will
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    not at least not by diffusion anyway
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    osmosis is the name specifically given
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    to the diffusion of water across such a
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    membrane for example if there is a
  • 00:04:53
    higher concentration of glucose outside
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    a cell the glucose cannot diffuse in to
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    balance the concentration so instead the
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    water moves out of the cell resulting in
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    a decrease in its mass the rate of
  • 00:05:04
    diffusion on osmosis can be increased by
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    increasing the difference in
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    concentrations increasing the
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    temperature or increasing the surface
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    area this is why the Villi and your
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    small intestinal lumpy as well as
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    alveoli in your lungs and R hair cells
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    for example too the Practical on osmosis
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    goes as follows cut equal size cylinders
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    from a potato or other vegetable weigh
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    them and place in test tubes with
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    varying concentration of sugar solution
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    after a day or so we remove them dab the
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    excess water off their surface and reway
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    we calculate percentage change in mass
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    by doing final Mass takeaway initial
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    mass divided by the initial mass time
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    100 if it's lighter than it was before
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    this must be a negative change in mass
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    we plot these percentages against sugar
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    concentration and we draw a line of best
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    fit where this crosses the x- axis is
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    what concentration should result in no
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    change in mass so no osmosis so this
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    means this must be the same as the
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    concentration inside the pot glucose and
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    other nutrients and minerals can move
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    through a membrane by active transport
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    where carrier proteins use energy to
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    move substances through the membrane as
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    there's energy used this can actually
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    move them against a concentration
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    gradient for example moving mineral ions
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    into plant root hair cells eukaryotic
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    cell nuclei contain DNA which is stored
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    in several chromosomes humans have 23
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    pairs of these in every nucleus so we
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    call them diploid cells that's not the
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    case for gtes though they have half so
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    just 23 not 23 pairs so therefore we
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    call them haid cells new cells must
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    constantly be made for growth and repair
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    they do this by duplicating by mitosis
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    here's the process the mitosis process
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    the genetic material is duplicated and
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    the number of ribosomes and mitochondria
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    is doubled as well the nucleus breaks
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    down and one set of each chromosome pair
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    is pulled to opposite sides of the cell
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    a new nucleus forms in each of these to
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    house the copied chromosomes and we now
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    have two identical cells cells
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    specialize depending on the function
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    they need to fulfill for example nerve
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    muscle root hair xylm Flo cells stem
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    cells are those that haven't yet
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    specialized they're found in human and
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    animal embryos and the merry stem of
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    plants that's the top of the choot stem
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    cells are made in your bone marrow
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    throughout your life as well but these
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    ones can only specialize into blood
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    cells we can use them cells to combat
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    conditions like diabetes and paralysis
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    in fact right out of the movie the
  • 00:07:22
    island people are now getting clones of
  • 00:07:25
    themselves made then harvesting the stem
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    cells as these won't be rejected by the
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    patient personally I think this is a
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    dystopian man-made horror Beyond
  • 00:07:32
    Comprehension you have to weigh up the
  • 00:07:34
    ethical Arguments for yourself cloning
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    plants can be used to prevent species
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    from becoming extinct or produce crops
  • 00:07:39
    with specific characteristics our
  • 00:07:41
    nervous system it consists of the CNS
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    that's central nervous system that's the
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    brain and spinal cord and the pns
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    peripheral nervous system the nerves
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    that go through the rest of the body a
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    receptor for example skin detects a
  • 00:07:54
    change due to a stimulus like a hot hob
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    an electrical signal travels to the
  • 00:07:59
    spine through sensory and relay neurons
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    nerve cells the signal travels across
  • 00:08:03
    the gap between these neurons called the
  • 00:08:05
    sinapse by a neurotransmitter chemical
  • 00:08:08
    once at the spine the signal can go to
  • 00:08:10
    the brain where you can make the
  • 00:08:11
    conscious decision to act the signal
  • 00:08:13
    then goes back to an affector like the
  • 00:08:16
    muscle in your arm via relay and motor
  • 00:08:19
    neurons so that you move your arm a
  • 00:08:21
    reflex is when the signal bypasses the
  • 00:08:23
    brain and goes straight through the
  • 00:08:24
    spine to the affector this is a reflex
  • 00:08:27
    arc this of course is much faster than a
  • 00:08:29
    con decision glands can also be
  • 00:08:31
    effective which produce specific
  • 00:08:33
    chemicals your body needs depending on
  • 00:08:34
    the situation for example your salivary
  • 00:08:36
    glands in your mouth making saliva when
  • 00:08:39
    you eat food you can investigate into
  • 00:08:41
    reaction Times by holding the bottom of
  • 00:08:42
    a ruler between a person's finger and
  • 00:08:44
    thumb and drop it without warning then
  • 00:08:46
    you measure the distance it falls before
  • 00:08:48
    they catch it do this multiple times and
  • 00:08:50
    take a mean average not too many times
  • 00:08:52
    though as their nervous systems will
  • 00:08:53
    start to get a bit better at reacting to
  • 00:08:56
    this you can introduce an independent
  • 00:08:57
    variable like a stimulant for example
  • 00:08:59
    coffee or a sugary drink or a depressant
  • 00:09:01
    which will have the opposite effect
  • 00:09:02
    although I can't think of any ones that
  • 00:09:04
    are legal for you at the minute to see
  • 00:09:06
    how they decrease or increase Reaction
  • 00:09:08
    Time respectively you could calculate
  • 00:09:10
    the reaction time from the distance
  • 00:09:12
    using suvat S = half a^2 but you'll
  • 00:09:15
    never be expected to do that in this
  • 00:09:17
    paper but it's something you could
  • 00:09:18
    mention if you were asked a six marker
  • 00:09:20
    on this there are three parts of the
  • 00:09:22
    brain you need to know the cerebral
  • 00:09:24
    cortex is responsible for higher level
  • 00:09:26
    functions like memory speech and problem
  • 00:09:28
    solving the arum is responsible for your
  • 00:09:30
    motor skills movement balance and
  • 00:09:32
    coordination the medulla onunga controls
  • 00:09:35
    unconscious actions your body takes you
  • 00:09:37
    don't think about them like your heart
  • 00:09:39
    and breathing rates it's also what
  • 00:09:41
    controls the release of adrenaline MRI
  • 00:09:44
    scans magnetic resonance imaging are a
  • 00:09:46
    way of seeing the activity in your brain
  • 00:09:48
    safely if something goes wrong with your
  • 00:09:50
    brain though it can be very difficult or
  • 00:09:51
    impossible to treat without damaging
  • 00:09:53
    important parts of it your eyes are the
  • 00:09:55
    most mind-bogglingly designed cameras
  • 00:09:58
    ever conceived of a modation is the ey's
  • 00:10:00
    ability to change the shape of the lens
  • 00:10:02
    in order to focus light that comes from
  • 00:10:04
    objects that are different distances
  • 00:10:06
    away on the retina to focus light that
  • 00:10:08
    comes from objects that are far away the
  • 00:10:10
    ciliary muscles relax and the suspensory
  • 00:10:13
    ligaments tighten they're both connected
  • 00:10:15
    to the lens this results in the lens
  • 00:10:17
    becoming thin and that means that light
  • 00:10:19
    is only refracted a little bit and that
  • 00:10:21
    focuses the light on the retina to focus
  • 00:10:24
    on near objects the opposite is true the
  • 00:10:26
    ciliary muscles contract the suspensory
  • 00:10:28
    ligaments slacken and the lens becomes
  • 00:10:30
    fatter or thicker and so that means that
  • 00:10:32
    it becomes more powerful actually so
  • 00:10:34
    light is refracted more which means that
  • 00:10:36
    the light coming from the object still
  • 00:10:37
    converges meets focuses on the retina so
  • 00:10:41
    you can see a clear image the pupil the
  • 00:10:43
    hole in the iris can change size
  • 00:10:45
    depending on the light intensity hitting
  • 00:10:47
    the eye the cornea is the transparent
  • 00:10:49
    outer layer where light enters the eye
  • 00:10:51
    it has a slight lensing effect itself
  • 00:10:53
    while the White surface that covers the
  • 00:10:55
    rest is called the Scara the light is
  • 00:10:57
    focused then on the retina the back of
  • 00:10:59
    the eye which consists of Rod and Cone
  • 00:11:01
    stells which respond to light rods can
  • 00:11:03
    only detect light intensity so no color
  • 00:11:06
    while there are three different types of
  • 00:11:07
    cones which detect green blue or red
  • 00:11:10
    wavelengths of light a mix of which will
  • 00:11:12
    produce the colors we then perceive when
  • 00:11:15
    the signal reaches our brain via the
  • 00:11:16
    optic nerve myopia is the medical term
  • 00:11:19
    for shortsightedness you can't focus on
  • 00:11:21
    Far objects hyperopia is
  • 00:11:24
    long-sightedness glasses or contact
  • 00:11:26
    lenses are usually used to mitigate this
  • 00:11:28
    by slightly converging or diverging the
  • 00:11:30
    light before it enters the eye laser eye
  • 00:11:32
    surgery aims to change the shape of the
  • 00:11:33
    cornea to achieve the same effect in
  • 00:11:36
    order to reproduce sexually gametes sex
  • 00:11:38
    cells must be made this happens by
  • 00:11:41
    meiosis for example in the testes to
  • 00:11:43
    make sperm the chromosomes in a diploid
  • 00:11:45
    cell that is 23 pairs for us are copied
  • 00:11:49
    similar chromosomes then pair up and the
  • 00:11:51
    genes are swapped between them the cell
  • 00:11:53
    then divides to make two diploid cells
  • 00:11:55
    which then divide again along with the
  • 00:11:57
    chromosomes themselves to make make four
  • 00:11:59
    haid cells ready to fuse with another
  • 00:12:02
    gamt which in this case would be an egg
  • 00:12:04
    this is one way that variation occurs in
  • 00:12:06
    Offspring plants do this with pollen and
  • 00:12:08
    egg cells but they can also reproduce
  • 00:12:09
    asexually but as it doesn't evolve
  • 00:12:11
    gametes the daughter cells will be
  • 00:12:13
    genetically identical so a clone of the
  • 00:12:15
    parent is made by mitosis an advantage
  • 00:12:18
    of sexual reproduction is that variation
  • 00:12:20
    occurs which can result in organisms
  • 00:12:22
    becoming better suited to their
  • 00:12:23
    environment more in this in a bit so
  • 00:12:25
    more likely to survive an advantage for
  • 00:12:27
    asexual is that only one paent is needed
  • 00:12:29
    so for example a plant on its Lonesome
  • 00:12:31
    can still reproduce in order for the
  • 00:12:32
    species to survive another thing that
  • 00:12:35
    can do both is the parasite that causes
  • 00:12:37
    malaria genome is the term given to all
  • 00:12:39
    the genetic material in an organism this
  • 00:12:42
    code is stored in DNA of course which is
  • 00:12:44
    a two stranded polymer in a double helix
  • 00:12:47
    shape a gene is a section of DNA that
  • 00:12:50
    codes for a specific protein the Human
  • 00:12:52
    Genome Project completed its initial
  • 00:12:54
    goal in 2003 when scientists mapped out
  • 00:12:57
    what every Gene is responsible for
  • 00:12:58
    coding this is powerful because it can
  • 00:13:00
    help us identify what genes cause
  • 00:13:03
    diseases or inherited disorders genotype
  • 00:13:06
    is the term given to what code is stored
  • 00:13:08
    in your DNA specifically well phenotype
  • 00:13:11
    is how that code is expressed in your
  • 00:13:14
    characteristics what proteins are made
  • 00:13:17
    it affects your physiology for triple
  • 00:13:19
    you need to know that the monomers
  • 00:13:20
    between the two strands are called
  • 00:13:22
    nucleotides and they're made from a
  • 00:13:24
    sugar and phosphate group of which there
  • 00:13:26
    are four types A T C and G G you don't
  • 00:13:29
    need to know what the names are but a
  • 00:13:32
    and t always match to each other in the
  • 00:13:34
    sequence as do C and G every three of
  • 00:13:37
    these bases we can call them are a code
  • 00:13:40
    for an amino acid the sequence is copied
  • 00:13:42
    by mRNA this copy is then taken out of
  • 00:13:45
    the nucleus to a ribosome in the cell
  • 00:13:47
    where amino acids are connected in the
  • 00:13:50
    order needed which makes a protein the
  • 00:13:52
    shape of which affects His function they
  • 00:13:54
    need to be folded as well first harmful
  • 00:13:56
    mutations can change a gene so much that
  • 00:13:59
    it results in a protein being
  • 00:14:00
    synthesized that doesn't do the job it's
  • 00:14:02
    supposed to we now know that some DNA
  • 00:14:04
    however doesn't directly code for
  • 00:14:06
    proteins but it influences how other
  • 00:14:08
    genes are expressed this is the realm of
  • 00:14:10
    epigenetics and it's changing the way
  • 00:14:12
    that we view DNA quite drastically back
  • 00:14:15
    to double some characteristics are
  • 00:14:17
    controlled by just one gene like color
  • 00:14:19
    blindness these different types of the
  • 00:14:21
    same gene are called alals usually
  • 00:14:23
    characteristics are dependent on two or
  • 00:14:25
    more genes though and them interacting
  • 00:14:28
    dominant Al are those that result in a
  • 00:14:30
    characteristic being expressed even if
  • 00:14:32
    there is another alil present a
  • 00:14:34
    recessive alil for example if you have
  • 00:14:36
    the Al's Big B little B for eye color
  • 00:14:39
    Big B being brown little B being blue
  • 00:14:42
    you will have brown eyes it's only when
  • 00:14:44
    there's no dominant alal in this case
  • 00:14:46
    that the recessive alil is expressed so
  • 00:14:49
    me having blue eyes I must have the gene
  • 00:14:52
    little B little B Big B Big B or little
  • 00:14:54
    B little B are called homozygous as they
  • 00:14:57
    only have one type of alal where whereas
  • 00:14:59
    Big B little B is what we call
  • 00:15:00
    heterozygous we can use a punet square
  • 00:15:03
    to predict the probability of a certain
  • 00:15:05
    phenotype my parents have brown eyes but
  • 00:15:07
    they both have heterozygous alals for
  • 00:15:10
    eye color there are three different
  • 00:15:12
    outcomes of these combining with a 25%
  • 00:15:15
    chance of making me that's little be
  • 00:15:17
    little be so I'm not so much one in a
  • 00:15:19
    million more one in four my sister has
  • 00:15:21
    brown eyes but her son has blue eyes so
  • 00:15:23
    she must be Big B little B eye color is
  • 00:15:26
    by The Bu but sums can result in
  • 00:15:29
    disorders being inherited for example
  • 00:15:31
    polya extra fingers or toes which is
  • 00:15:34
    caused by a dominant alil or cystic
  • 00:15:36
    vibrosis which is caused by a recessive
  • 00:15:39
    alal even if two parents don't have
  • 00:15:41
    cystic fibrosis they could still be
  • 00:15:42
    carrying the recessive alil so their
  • 00:15:45
    child could have the disorder human DNA
  • 00:15:47
    is contain in 23 pairs of chromosomes
  • 00:15:49
    but only one pair determines sex if you
  • 00:15:52
    have XX chromosomes you are female XY
  • 00:15:55
    you're male the expression of these
  • 00:15:56
    genes affects every cell in your body
  • 00:15:59
    every aspect of your physiology we can
  • 00:16:01
    also make a punet square for these as
  • 00:16:03
    you can see there's a 50/50 chance of a
  • 00:16:05
    child being male or female variation is
  • 00:16:07
    a result of the genes inherited from an
  • 00:16:09
    organism's parents and also
  • 00:16:11
    environmental factors Charles Darwin's
  • 00:16:13
    theory of evolution states that random
  • 00:16:15
    variation in Offspring will result in
  • 00:16:17
    some being better suited to their
  • 00:16:18
    environment than others and so are more
  • 00:16:20
    likely to survive and reproduce but like
  • 00:16:22
    we've seen we know that our DNA is able
  • 00:16:23
    to respond to the environment in order
  • 00:16:25
    to turn genes on and off depending on
  • 00:16:27
    whether they're needed or not for
  • 00:16:29
    example there were some blind
  • 00:16:30
    translucent skin mackerel that were
  • 00:16:31
    found in a dark cave when they were bred
  • 00:16:33
    with normal mackerel in sunlight they
  • 00:16:35
    regained fully working eyes and opaque
  • 00:16:37
    skin within a few Generations Jean
  • 00:16:39
    Baptist Lamar's Theory asserted that
  • 00:16:41
    adaptation of variation is Guided by DNA
  • 00:16:44
    in response to a changing environment
  • 00:16:46
    this was scoffed at but we now know that
  • 00:16:48
    there is some truth to this thanks to
  • 00:16:50
    the discoveries made in epigenetics
  • 00:16:53
    bacterial resistance is largely
  • 00:16:54
    considered to be evidence of darwinian
  • 00:16:56
    evolution bacteria divid mutations occur
  • 00:16:59
    and inevitably a bacterium with an
  • 00:17:01
    increased resistance to antibiotics will
  • 00:17:03
    be produced that's why we only want to
  • 00:17:05
    use them when absolutely necessary it
  • 00:17:07
    also means you have to complete the
  • 00:17:08
    whole course of antibiotics if you don't
  • 00:17:11
    weaker bacteria will have been killed
  • 00:17:12
    off but more resistant ones will still
  • 00:17:14
    be there and then they'll reproduce and
  • 00:17:17
    make you even more ill if organisms are
  • 00:17:19
    able to produce fertile offspring we say
  • 00:17:21
    they're of the same species tigers and
  • 00:17:23
    lions have been known to make lier
  • 00:17:25
    Offspring but as they're infertile we
  • 00:17:27
    don't consider and lines to be the same
  • 00:17:29
    species we can selectively breed living
  • 00:17:32
    things with desired characteristics to
  • 00:17:34
    enhance these for example breeding dogs
  • 00:17:36
    to produ breeds like labrador's
  • 00:17:38
    colleagues and if you're into
  • 00:17:40
    undesirable characteristics pugs too
  • 00:17:42
    just for triple Johan Mendel was one of
  • 00:17:44
    the first people to assert that
  • 00:17:45
    characteristics were determined by units
  • 00:17:48
    that are passed onto Offspring due to
  • 00:17:50
    the discovery of genes and chromosomes
  • 00:17:51
    he was proven largely correct
  • 00:17:54
    advancements in biology over the last
  • 00:17:56
    few decades mean that we can also
  • 00:17:58
    genetically modify organisms if we don't
  • 00:18:00
    want to wait for selective breeding to
  • 00:18:01
    do the job or when it can't actually
  • 00:18:03
    achieve what we want it to for good or
  • 00:18:05
    ill for example scientists have
  • 00:18:07
    genetically modified bacteria to produce
  • 00:18:09
    insulin which can be harvested and used
  • 00:18:11
    to treat people with diabetes
  • 00:18:13
    genetically modifying crops is one way
  • 00:18:15
    of boosting their yields or nutritional
  • 00:18:18
    value for example golden rice has a gene
  • 00:18:20
    inserted into it that produces vitamin A
  • 00:18:23
    it was developed to combat diets in
  • 00:18:25
    certain areas that were lacking in this
  • 00:18:27
    other GM crops have been modified to be
  • 00:18:29
    more resistant to diseases for example
  • 00:18:32
    the process of genetic engineering goes
  • 00:18:34
    as follows a gene is chemically cut from
  • 00:18:36
    the organism that has the desired
  • 00:18:38
    characteristic this is done using
  • 00:18:40
    enzymes for example the gene from a
  • 00:18:42
    jellyfish that causes it to glow in the
  • 00:18:44
    dark this is then inserted into a vector
  • 00:18:47
    like a bacteria plasmid or virus that in
  • 00:18:50
    turn inserts the gene into another
  • 00:18:52
    organism say a bunny rabbit but it must
  • 00:18:54
    be done in the early stage of its
  • 00:18:56
    development say just after the Y has
  • 00:18:58
    been fertilized as this is the only way
  • 00:19:00
    you can be sure that the gene will be
  • 00:19:02
    present in every cell of the bunny as it
  • 00:19:04
    grows by the way I didn't make up this
  • 00:19:06
    example this has actually been done
  • 00:19:09
    fossils are the remains of organisms
  • 00:19:11
    that died a very long time ago the
  • 00:19:12
    classic fossils we think about are the
  • 00:19:14
    bones that we dig up but they're not
  • 00:19:16
    strictly speaking bones anymore in fact
  • 00:19:18
    minerals have replaced the organic
  • 00:19:20
    material to effectively leave Rock in
  • 00:19:23
    exactly the same shape as the bone
  • 00:19:26
    sometimes there can still be organic
  • 00:19:27
    tissue left behind if the conditions for
  • 00:19:29
    Decay are not present Footprints left in
  • 00:19:32
    mud that have hardened over time for
  • 00:19:34
    example are also considered fossils as
  • 00:19:36
    well as any other trace of an organism
  • 00:19:39
    it doesn't have to be the organism
  • 00:19:40
    itself CBD cardiovascular disease is an
  • 00:19:44
    example of a non-communicable disease as
  • 00:19:46
    the cause of it comes from inside your
  • 00:19:48
    body other examples of such diseases
  • 00:19:51
    include autoimmune conditions like
  • 00:19:53
    allergic reactions and cancer a
  • 00:19:55
    communicable disease must be caused by a
  • 00:19:57
    pathogen that enters your body that will
  • 00:19:59
    cause a viral bacterial or fungal
  • 00:20:02
    infection again more on these in a bit
  • 00:20:04
    back to non-communicable diseases
  • 00:20:06
    obesity and too much sugar can cause
  • 00:20:08
    type 2 diabetes a bad diet smoking and
  • 00:20:11
    lack of exercise can affect the risk of
  • 00:20:12
    heart disease alcohol can cause liver
  • 00:20:15
    diseases smoking lung disease or cancer
  • 00:20:18
    a carcinogen is the name given to
  • 00:20:20
    anything that increases the risk of
  • 00:20:21
    cancer for example ionizing radiation
  • 00:20:24
    cancer is a result of damaged cells
  • 00:20:26
    dividing uncontrollably lead into tumors
  • 00:20:29
    benign cancers don't spread through the
  • 00:20:31
    body and they're relatively easy to
  • 00:20:32
    treat however malignant cancers are when
  • 00:20:35
    these cancerous cells spread through
  • 00:20:37
    your body much worse BMI stands for body
  • 00:20:40
    mass index it's an indication of whether
  • 00:20:43
    or not somebody has a healthy weight or
  • 00:20:45
    not relative to their height the
  • 00:20:47
    equation is this BMI is equal to weight
  • 00:20:49
    well Mass we know don't we divided by
  • 00:20:52
    height squared and whatever number you
  • 00:20:53
    have will put you into certain bands
  • 00:20:56
    will determine whether or not you're a
  • 00:20:57
    healthy BMI overweight obese Etc as
  • 00:21:01
    mentioned just now communicable diseases
  • 00:21:03
    are caused by pathogens that can be
  • 00:21:05
    viruses bacteria fungi or protests these
  • 00:21:08
    are single celled parasites they all
  • 00:21:10
    reproduce in your body and cause damage
  • 00:21:12
    but viruses can't reproduce by
  • 00:21:14
    themselves a virus is in fact just a
  • 00:21:16
    protein casing that surrounds genetic
  • 00:21:18
    code that it injects into a cell which
  • 00:21:21
    causes the cell to produce more copies
  • 00:21:23
    of the virus the cell explodes and the
  • 00:21:26
    virus goes on to infect more cells
  • 00:21:28
    creepy isn't it HIV is an STD or STI
  • 00:21:31
    sexually transmitted disease or
  • 00:21:33
    infection that compromises your immune
  • 00:21:35
    system this is also called aids for
  • 00:21:37
    short it can also be spread by people
  • 00:21:39
    sharing needles bacteria on the other
  • 00:21:42
    hand release toxins that damage your
  • 00:21:44
    body cells fungi do something similar
  • 00:21:47
    like athletes foot while protus do all
  • 00:21:49
    sorts of different things for example
  • 00:21:50
    malaria is caused by a proest that
  • 00:21:52
    burrows into red blood cells to multiply
  • 00:21:55
    then burst out destroying the red blood
  • 00:21:56
    cell in the process it's spread by
  • 00:21:58
    mosquitoes so we say mosquitoes are the
  • 00:22:01
    vector for the disease our bodies are
  • 00:22:03
    excellent at protecting us from these
  • 00:22:05
    pathogens though thank goodness skin is
  • 00:22:07
    the first barrier to them entering and
  • 00:22:08
    if they do enter your nose and trachea
  • 00:22:11
    they can be trapped by mucus acid and
  • 00:22:13
    enzymes in your digestive system will
  • 00:22:15
    destroy them too if they still manage to
  • 00:22:17
    enter the bloodstream though white blood
  • 00:22:19
    cells are ready to combat them one type
  • 00:22:20
    of these are called lymphocytes they
  • 00:22:22
    produce antitoxins to neutralize the
  • 00:22:24
    poisons pathogens produce and also they
  • 00:22:27
    make antibodies which stick to the
  • 00:22:29
    antigen on a pathogen and this stops
  • 00:22:31
    them from being able to infect more
  • 00:22:32
    cells and it makes them Clump together
  • 00:22:35
    fago sites are then able to ingest them
  • 00:22:37
    and Destroy them an antigen on a
  • 00:22:39
    pathogen will have a specific shape so
  • 00:22:41
    that means only an antibody that fits it
  • 00:22:43
    will neutralize it if pathogens are
  • 00:22:46
    unknown to the immune system lymphocytes
  • 00:22:48
    will start making all different shapes
  • 00:22:50
    until one fits miraculously your immune
  • 00:22:53
    system will then store a copy of this
  • 00:22:54
    antibody next to a copy of the antigen
  • 00:22:57
    so it's ready to stop it from causing an
  • 00:22:59
    infection next time you're exposed to it
  • 00:23:01
    you now have immunity a vaccine is a
  • 00:23:04
    dead or inert version of a pathogen
  • 00:23:06
    usually a virus that exposes your immune
  • 00:23:08
    system to the pathogen so it can produce
  • 00:23:10
    the antibody without it infecting you
  • 00:23:12
    for example the flu vaccine you're
  • 00:23:13
    injected with the virus that has been
  • 00:23:15
    irradiated so the DNA has been damaged
  • 00:23:18
    inside so it can't do the job
  • 00:23:20
    incidentally the co jab however was
  • 00:23:22
    intended to work differently instead
  • 00:23:23
    you're injected with the DNA technically
  • 00:23:26
    mRNA needed to trick your cells into
  • 00:23:28
    synthesizing part of the virus including
  • 00:23:31
    the antigen it was the first widely used
  • 00:23:33
    jab that used this mRNA technology just
  • 00:23:36
    for triple bacteria multiply by binary
  • 00:23:39
    fision so the number doubles every say
  • 00:23:41
    10 minutes so if we started with one
  • 00:23:43
    bacterium after an hour we'd have 2 to
  • 00:23:46
    the^ of 6 that's 64 after 6 hours that's
  • 00:23:49
    36 lots of 10 minutes so in theory we'd
  • 00:23:52
    have 2 to ^ of 36 that's in standard
  • 00:23:55
    form 6.87 * 10 10 we can do a itical on
  • 00:23:58
    this by producing a culture on agar in a
  • 00:24:01
    Petra dish using aseptic technique that
  • 00:24:03
    is making sure nothing else contaminates
  • 00:24:05
    the culture we lift the lid of the dish
  • 00:24:07
    towards a flame which causes other
  • 00:24:09
    microbes in the air to move away and
  • 00:24:10
    upwards from the dish and it destroys
  • 00:24:12
    them too using sterilized equipment we
  • 00:24:14
    can either put a drop of bacteria
  • 00:24:16
    culture in the middle or spread it all
  • 00:24:17
    around and put spots of different
  • 00:24:19
    antibiotics on top instead we put a few
  • 00:24:21
    bits of tape around the dish to hold the
  • 00:24:23
    lid on but not all the way around
  • 00:24:25
    otherwise air will not get in and the
  • 00:24:26
    bacteria will respire an aerobically we
  • 00:24:29
    then incubate it at 25° once the culture
  • 00:24:32
    has grown we can either calculate the
  • 00:24:33
    size of the culture from an initial drop
  • 00:24:35
    or the area in which bacteria did not
  • 00:24:37
    grow or were killed by an antibiotic to
  • 00:24:39
    then compare with others in both cases
  • 00:24:41
    we use Pi r^ squ or pi d^2 over 4 to
  • 00:24:44
    calculate the area of the circles
  • 00:24:46
    antibiotics kill bacteria they don't
  • 00:24:49
    kill viruses penicillin was the first
  • 00:24:51
    one there are good bacteria in our body
  • 00:24:53
    so antibiotics are designed to be as
  • 00:24:56
    specific as possible because you don't
  • 00:24:57
    want to damage those or your body cells
  • 00:24:59
    either problem is as bacteria mutate
  • 00:25:02
    they can become resistant to them so the
  • 00:25:04
    more you use them the less effective
  • 00:25:05
    they become drugs used to be extracted
  • 00:25:08
    from plants and other organisms for
  • 00:25:10
    example aspirin comes from willow trees
  • 00:25:12
    penicillin from a mold now synthesizing
  • 00:25:14
    drugs is one of the biggest industries
  • 00:25:16
    on the planet they have to be trial to
  • 00:25:18
    see how effective they are and to check
  • 00:25:20
    for side effects first we do lab trials
  • 00:25:22
    on Cell tissue than trials on animals
  • 00:25:25
    next human trials we give the drug to a
  • 00:25:27
    group of people but we also give a
  • 00:25:29
    placebo to a control group without
  • 00:25:31
    telling them say a pill that's just
  • 00:25:33
    sugar not the actual drug this is what
  • 00:25:35
    we call a blind trial because the test
  • 00:25:38
    subjects don't know what they're taking
  • 00:25:40
    a double blind trial is when even those
  • 00:25:42
    analyzing the results from the tests
  • 00:25:44
    aren't aware of which group is which and
  • 00:25:47
    that's to eliminate any bias just for
  • 00:25:49
    triple this is a crazy one monoclonal
  • 00:25:52
    antibodies they're made from clones of a
  • 00:25:54
    cell which is able to produce a specific
  • 00:25:56
    antibody to combat a disease
  • 00:25:58
    this is achieved by combining
  • 00:26:00
    lymphocytes from me tumor cells and this
  • 00:26:02
    makes a hybridoma cell this is then
  • 00:26:05
    cloned to produce a lot of antibodies
  • 00:26:07
    ready to treat a patient these
  • 00:26:09
    monoclonal antibodies can also be used
  • 00:26:10
    for medical diagnosis pathogen detection
  • 00:26:13
    in a lab or even just identifying
  • 00:26:15
    molecules in tissue by binding them to a
  • 00:26:18
    dye so they glow when grouped together
  • 00:26:21
    because they'll be designed to bind to a
  • 00:26:23
    specific molecule the downside to these
  • 00:26:25
    is that the side effects are turning out
  • 00:26:26
    to be worse than scientists expected so
  • 00:26:29
    I hope you found that helpful leave a
  • 00:26:30
    like if you did and pop any questions or
  • 00:26:32
    comments below and hey after you've done
  • 00:26:34
    the exam come back here and tell us all
  • 00:26:35
    how you found it we'd love to know click
  • 00:26:37
    on a card to go to the playlist for all
  • 00:26:39
    six papers I'll see you in the next
  • 00:26:41
    video best of luck
Tags
  • cells
  • genetics
  • natural selection
  • genetic modification
  • health
  • enzymes
  • osmosis
  • vaccines
  • diseases
  • immunity
  • monoclonal antibodies