BIOLOGY explained in 17 Minutes

00:17:31
https://www.youtube.com/watch?v=3tisOnOkwzo

概要

TLDRA videó bemutatja a Föld keletkezését és a biológia alapjait, beleértve a sejtek felépítését, a DNS szerepét, a gének öröklődését és a sejtosztódás folyamatát. A prokarióták és eukarióták közötti különbségeket is érinti, valamint a mutációk és a természetes szelekció fogalmát. A baktériumok és vírusok közötti különbségeket is megemlíti, és bemutatja az idegrendszer működését. A videó végén a Brilliant platformot ajánlja, amely interaktív tanulási lehetőségeket kínál.

収穫

  • 🌍 A Föld 4,5 milliárd éve keletkezett.
  • 🧬 A biológia a kémia álcázott formája.
  • 🔬 A prokarióták egyszerű sejtek, az eukarióták bonyolultabbak.
  • 📜 A DNS tárolja a genetikai információt.
  • ⚛️ A sejtosztódás mitózissal és meiózissal történik.
  • 🌱 A természetes szelekció a legjobban alkalmazkodó fajok túlélését jelenti.
  • 🔄 A mutációk a DNS szekvenciájában bekövetkező változások.
  • 🦠 A baktériumok élő sejtek, a vírusok nem élő organizmusok.
  • ⚡ Az idegrendszer elektromos jelek segítségével működik.
  • 💡 Az ATP energiaforrás a sejtekben.

タイムライン

  • 00:00:00 - 00:17:31

    A sejtek osztódása két fő mechanizmuson keresztül történik: mitózis és meiózis. A mitózis során a sejtek azonos másolatokat készítenek, míg a meiózis során a gaméták, azaz a spermiumok és petesejtek keletkeznek. A sejtek életciklusa során a legtöbb időt interfázisban töltik, ahol növekednek és másolják a DNS-t. A sejtek osztódása és a gének öröklődése kulcsszerepet játszik a biológiai sokféleség és az evolúció folyamatában.

マインドマップ

ビデオQ&A

  • Mi a biológia?

    A biológia az élet tanulmányozása, amely valójában a kémia álcázott formája.

  • Mik a prokarióták és eukarióták?

    A prokarióták egyszerű sejtek, míg az eukarióták bonyolultabb sejtek, amelyek sejtorganellumokat tartalmaznak.

  • Mi a DNS szerepe?

    A DNS tárolja a genetikai információt, amely meghatározza a szervezet jellemzőit.

  • Hogyan történik a sejtosztódás?

    A sejtosztódás mitózissal és meiózissal történik, amelyek különböző célokat szolgálnak.

  • Mi a természetes szelekció?

    A természetes szelekció a legjobban alkalmazkodó fajok túlélését és szaporodását jelenti.

  • Mik a mutációk?

    A mutációk a DNS szekvenciájában bekövetkező változások, amelyek hatással lehetnek a gének működésére.

  • Mi a különbség a baktériumok és vírusok között?

    A baktériumok élő sejtek, míg a vírusok nem élő organizmusok, amelyek csak gazdaszervezetben képesek szaporodni.

  • Hogyan működik az idegrendszer?

    Az idegrendszer elektromos jelek segítségével kommunikál a test különböző részei között.

  • Mi az ATP szerepe?

    Az ATP energiaforrásként működik a sejtekben, lehetővé téve a különböző biokémiai reakciókat.

  • Mi a riboszóma szerepe?

    A riboszómák fehérjék szintéziséért felelősek, a DNS információját használva.

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  • 00:00:00
    Hi. You’re on a rock, floating  in space. Have did we get here?
  • 00:00:04
    Well, about 4.5 billion years ago, the earth  was big ball of flaming rocks, constantly
  • 00:00:09
    bombarded by even more rocks from space. Fun  fact! Those rocks probably had some water
  • 00:00:13
    inside them, which has now turned into steam. Breaking news! The earth is cooling down. Oh yeah,
  • 00:00:19
    did I mention tha- [it’s raining.] Whoops, everything’s flooded, but hey,
  • 00:00:23
    at least there’s some cool stuff at the bottom,  like hydrothermal vents, which are piping hot
  • 00:00:26
    and filled with a bunch of chemicals, that can  make some very interesting stuff. Wait a minute,
  • 00:00:31
    what the heck is going on here? [Biology]
  • 00:00:36
    Biology is the study of life, but really,  it’s just chemistry in disguise. I mean
  • 00:00:41
    you and I are basically just a big ball  of molecules that can make funny sounds.
  • 00:00:50
    Carbohydrates give you quick energy, lipids store  long term energy and make membranes, proteins make
  • 00:00:55
    up tissues and nucleic acids make DNA. Also, to  make all the chemical reactions possible, living
  • 00:01:00
    beings, have inside of them a bunch of enzymes. They’re special proteins that act as catalysts,
  • 00:01:04
    which just means they help chemical reactions  speed up by either breaking down or combining
  • 00:01:08
    one specific thing. For example, lactase  breaks down lactose, the sugar found in milk.
  • 00:01:14
    Ok, so enzymes make life possible  by speeding up chemical reactions,
  • 00:01:17
    but what even is…life? Scientists don’t really  seem to agree, but obviously a cat is different
  • 00:01:23
    from a rock. The cat can produce energy by  metabolizing food, it can grow and develop,
  • 00:01:28
    reproduce, and it responds to the  environment, whereas the rock does not.
  • 00:01:32
    Also, unlike rocks, every living thing on  earth is made of cells, of which there’s
  • 00:01:35
    two main categories: Eukaryotes and prokaryotes. Eukaryotes have fancy organelles which are bound
  • 00:01:41
    by membranes, like the nucleus, inside of which is  DNA. Prokaryotes, have none of those organelles,
  • 00:01:46
    and the DNA is just kind of chilling  there, like freely floating around.
  • 00:01:50
    This is why Prokaryotes are just  single cell organisms like bacteria
  • 00:01:53
    and archea whereas eukaryotes can form  complex organisms like protists, fungi,
  • 00:01:57
    plants and animals. These are what’s known  as “kingdoms”, which is a taxonomic rank,
  • 00:02:01
    so basically, how we classify different living  things and how they’re related to one another.
  • 00:02:06
    Because there are quite a few species of  life on this planet, and naming them cat,
  • 00:02:09
    dangerous cat and water cat wouldn’t really be  all that helpful, we also give every species
  • 00:02:13
    a unique and unambiguous scientific name  consisting of the genus and the species.
  • 00:02:17
    One thing every species has  in common is homeostasis, aka,
  • 00:02:21
    keeping certain conditions in check, so ya don’t  die. If you feel warm, your body will sweat,
  • 00:02:25
    if you’re cold, your body will shiver. A cell does kind of the same thing just
  • 00:02:29
    that it balances out concentrations of certain  chemicals. You see, enzymes for example, only
  • 00:02:34
    work in a very specific environment, let’s say at  some specific pH value. If this changes too much,
  • 00:02:38
    the enzymes will denature and won’t work anymore.  To counter this, the cell needs to constantly keep
  • 00:02:43
    up this specific pH value, which is controlled  by the concentration of acid and base molecules.
  • 00:02:48
    Ok. But like, how does the cell do that? The secret lies in the cell membrane. You see,
  • 00:02:54
    it’s a semipermeable phospholipid bilayer,  okay that’s way too many words, all it is,
  • 00:02:58
    is two layers of these funky looking molecules  with a polar head and a nonpolar tail.
  • 00:03:03
    This allows small molecules like water  and oxygen to slip right through,
  • 00:03:06
    whereas larger particles like ions need special  channels that can be opened or closed, which
  • 00:03:10
    gives the cell control of what goes in and out. Naturally, particles move with the gradient,
  • 00:03:14
    so from a place of high concentration  to a place of low concentration. Or,
  • 00:03:17
    in the case of water, it can also move to a place  of high solute concentration, so for example salt.
  • 00:03:22
    Welcome to Biology Pro Tips Season 1, tip  of the day: do not drink too much saltwater.
  • 00:03:27
    There’s a bunch of salt in saltwater, in  fact, more salt than inside of a cell,
  • 00:03:32
    which means it will draw water from your cells and  dehydrate you. Yeah that’s it have a great day.
  • 00:03:38
    The process of balancing out gradients is known  as “diffusion” and happens automatically, but,
  • 00:03:42
    by using a little bit of energy, particles  can actively be moved against the gradient.
  • 00:03:47
    The energy comes from Adenosine  Triphosphate or ATP. To be exact,
  • 00:03:51
    the highly energetic chemical bonds between the  phosphate groups can be broken to obtain energy.
  • 00:03:55
    This is kind of important, as  in, every organism and every cell
  • 00:03:59
    needs to make ATP for example, through cellular  respiration which happens in the mitochondria:
  • 00:04:05
    Together with oxygen, glucose, so sugar, is  turned into water, carbon dioxide and ATP.
  • 00:04:10
    This is nice, but it only works if you already  have glucose. Humans are “heterotrophs”. They
  • 00:04:14
    eat food, inside of which is sugar,  which is then broken down into glucose.
  • 00:04:18
    Plants on the other hand are “autotrophs”.  Simply put, they said “screw food, I’ll just
  • 00:04:23
    make my own glucose by staring at the sun”. You  see, plant cells have small organelles called
  • 00:04:28
    “chloroplasts” inside of which is chlorophyll,  which absorbs red and blue light but reflects
  • 00:04:32
    green light, which is why most plants look green. The absorbed energy from light is used to split
  • 00:04:36
    water and make a special form of carbon dioxide  which can then be turned into glucose and oxygen.
  • 00:04:41
    Okay quick recap, once you have glucose, either  from food or photosynthesis, you can do cellular
  • 00:04:46
    respiration, to get energy in the form of ATP. Chemically, ATP is what’s known as a nucleotide.
  • 00:04:51
    It has a phosphate group, a five carbon sugar and  a nitrogenous base. You know what else is made of
  • 00:04:56
    nucleotides? Deoxyribonucleic acid, or DNA. It consists of two strands of nucleotides,
  • 00:05:01
    with the sugar and phosphate groups, but the  actually important part is the nitrogenous base,
  • 00:05:05
    which comes in four flavours: Adenine,  Thymine, Cytosine and Guanine.
  • 00:05:09
    These bases can form base pairs through  hydrogen bonds, where Adenine goes with Thymine,
  • 00:05:14
    and Cytosine goes with Guanine. These bonds  are what holds the two strands of DNA together.
  • 00:05:19
    Okay, but, how the heck does that store  genetic information? I’m glad you ask!
  • 00:05:25
    A “gene” is a section of this DNA  that codes for a special trait,
  • 00:05:28
    by carrying a certain sequence of base pairs,  which is like a recipe for making a protein.
  • 00:05:34
    Why proteins? Because they’re like really  important, they transport molecules,
  • 00:05:37
    act as enzymes and determine the way you look.  For example, the difference between brown and
  • 00:05:41
    blue eyes is the amount of a pigment called  “melanin” in the cells of the iris. The OCA2
  • 00:05:46
    Gene codes for “P-Protein” which we believe  controls the amount of melanin in cells,
  • 00:05:50
    meaning that the proteins made from this gene,  could be what determines your eye colour.
  • 00:05:54
    Cool! There’s just one issue: Your DNA  and its information is in the nucleus,
  • 00:05:59
    but proteins are made in organelles  called the ribosomes. How do we get the
  • 00:06:02
    information from A to B? The answer is RNA. It’s kind of like DNA, just that it’s most
  • 00:06:07
    often a single strand, it uses a ribose instead of  deoxyribose and instead of Thymine it uses Uracil,
  • 00:06:12
    which makes it less stable, but that’s besides  the point, here’s what RNA actually does:
  • 00:06:16
    Let’s say you want to make the protein  coded for by this gene. An enzyme called
  • 00:06:20
    “RNA polymerase” will split the DNA and make  a strand of RNA with the complementary bases,
  • 00:06:24
    essentially copying the information from the  DNA to the RNA. This is called “transcription”.
  • 00:06:29
    The new strand is called messenger  RNA or mRNA, because it carries this
  • 00:06:33
    message out of the nucleus to a ribosome. Remember how I said that a gene is like a
  • 00:06:37
    recipe for a protein? Well, on the mRNA, which  carries the same base sequence as that gene,
  • 00:06:42
    every group of three bases, which is called  a “codon”, codes for a specific amino acid,
  • 00:06:46
    which are the building blocks for proteins. Welcome to Biology Pro Tips Season 1, if you want
  • 00:06:48
    to decode a sequence of RNA, there is actually a  chart for that! Yeah that’s all have a great day.
  • 00:06:48
    These amino acids are carried by special  molecules called transfer RNA or tRNA,
  • 00:06:53
    which have a unique anticodon that can only  attach to its matching codon on the mRNA.
  • 00:06:58
    The job of the ribosome is to read over codons on  the mRNA and attach the matching tRNA molecules,
  • 00:07:03
    which then leave behind their amino acid. As the  ribosome moves along the mRNA and attaches more
  • 00:07:08
    tRNA, which happens a couple thousand times, the  amino acids combine into a “polypeptide chain”,
  • 00:07:13
    which is just a really long chain of  amino acids, that can be bunched up,
  • 00:07:17
    creased, smacked and folded into a protein. Okay, let’s recap: A gene is copied onto mRNA,
  • 00:07:23
    which is then used to build proteins  by assembling a chain of amino acids.
  • 00:07:26
    Aka transcription and translation. Hey, this genetics stuff is pretty
  • 00:07:34
    cool, can we learn more? Absolutely. Oh yeah did I mention that you have, like,
  • 00:07:40
    a bunch of DNA? You have about 20000 protein  coding genes, each thousands to millions of
  • 00:07:45
    bases long, and that only makes up around 1% of  your entire DNA, the rest is just non-coding.
  • 00:07:51
    PLUS, almost every cell in your body contains your  entire genetic code, but genes can be turned on or
  • 00:07:56
    off depending on the cell, which is good, because  otherwise your brain cells might just start
  • 00:08:00
    making stomach acid, which would not be good. FUN FACT! If you were to stretch out all the
  • 00:08:04
    DNA of just one single cell, it  would be about 2 meters long.
  • 00:08:08
    Wait a minute, how does that fit into a  microscopic cell? Well, if you were to look inside
  • 00:08:13
    the nucleus, you wouldn’t find the DNA floating  around like this or even this, no, you would
  • 00:08:17
    actually find lots of these worm looking things. To be exact, DNA is coiled up around Proteins
  • 00:08:22
    called “Histones”, which are then condensed into  strands of Chromatin, which are then coiled up
  • 00:08:25
    even more to make tightly packed units of DNA  called “Chromosomes”, which kinda look like
  • 00:08:30
    worms. Different sections on a chromosome carry  different genes, and the entire human genome is
  • 00:08:34
    split amongst 23 different chromosomes, although  every body cell has 2 copies of every chromosome,
  • 00:08:39
    one from the mother and one from the father. For most chromosomes, the two copies are
  • 00:08:43
    said to be homologous, meaning that they carry  the same genes in the same location. However,
  • 00:08:48
    the two versions of a gene can be different,  so the mother’s gene could code for brown eyes,
  • 00:08:51
    while the father’s gene codes for blue eyes. These  different versions of a gene are called “alleles”.
  • 00:08:56
    For most of your genes, you have 2 alleles, one on  each chromosome from either parent. These alleles
  • 00:09:01
    can be dominant or recessive, which determines  which of them is expressed. For example,
  • 00:09:06
    brown eye color is a dominant trait, which  is shown by an uppercase B, whereas blue
  • 00:09:10
    is recessive, which is shown by a lowercase b. All this means, is that if you have the dominant
  • 00:09:14
    brown allele, you will have brown eyes, no matter  what the second allele is. Only when there are
  • 00:09:18
    two recessive alleles will it be expressed. With this knowledge, we can predict the future!
  • 00:09:23
    Let’s look at how this trait is  inherited from parents to children:
  • 00:09:26
    Both of these parents have brown eyes, but  also have a recessive blue allele in their
  • 00:09:29
    genotype. Every child receives one allele  from each parent randomly, so these are the
  • 00:09:34
    possible combinations for the children. Most combinations contain the dominant
  • 00:09:37
    brown allele, so the child will have brown eyes.  But, there is a small chance that a child gets
  • 00:09:42
    two recessive alleles and has blue eyes, even  though both parents had brown eyes! You see,
  • 00:09:47
    it’s what’s on the inside that counts. Alright, that’s cool, but reality is not always
  • 00:09:51
    so simple. Some genes are not fully dominant, but  not fully recessive either, which means that the
  • 00:09:55
    phenotype, so the appearance, appears to mix. Crossing a red and a white snapdragon, where
  • 00:10:00
    red is “dominant” and white is “recessive” gives  you a pink phenotype which is somewhere inbetween,
  • 00:10:04
    aka intermediate inheritance. Or, crossing  a brown and a white cow where both colours
  • 00:10:08
    are dominant could give you spotted cow, so both  phenotypes are expressed equally, aka codominance.
  • 00:10:14
    Hey remember how I said almost all  chromosomes are homologous? Well,
  • 00:10:17
    there’s one exception: the sex chromosomes. Females have two big X chromosomes, whereas
  • 00:10:22
    males have one X and one smaller Y chromosome. These are partially homologous at the top,
  • 00:10:27
    but since the Y chromosome is so small,  it’s missing genes that are present
  • 00:10:30
    on the lower part of the X chromosome.  These genes are called “X-linked genes”.
  • 00:10:34
    If one of these genes is a recessive trait like  colour blindness, males are stuck with that trait,
  • 00:10:38
    whereas females probably have another  dominant allele, to override it. This
  • 00:10:42
    is why most colourblind people are male. Now, for genes to even be passed on,
  • 00:10:45
    the body has to make new cells which can  inherit the genes. There’s two main mechanisms:
  • 00:10:49
    Mitosis, which is how the body makes identical  copies of body cells to grow and repair tissues,
  • 00:10:54
    and Meiosis, which is how the body  makes gametes, so sperm and egg cells.
  • 00:10:58
    Mitosis starts with a diploid cell, so a cell with  two sets of chromosomes. These chromosomes consist
  • 00:11:03
    of one chromatid, which has to be replicated  for the new cell. After replication is when
  • 00:11:08
    you see the familiar X shape consisting of  two identical sister chromatids. These are
  • 00:11:12
    split into two identical diploid cells, with two  sets of chromosomes consisting of one chromatid.
  • 00:11:18
    Meiosis also starts with a diploid cell, but  after replication, the chromosomes comingle
  • 00:11:22
    and exchange genetic information in a process  called “crossing over”. The cell is then split
  • 00:11:27
    into two non-identical haploid cells. These  have one set of chromosomes, but they still
  • 00:11:32
    consist of 2 sister chromatids. These cells split  again into 4 genetically different haploid cells,
  • 00:11:37
    where each chromosomes has one chromatid. Meiosis produces haploid cells, so that when two
  • 00:11:42
    gametes combine into a fertilized egg or “zygote”,  it again has the correct number of chromosomes.
  • 00:11:47
    This is cool, but, cell division is only a tiny  part of a cell’s entire life cycle. Most of its
  • 00:11:51
    time is actually spent in interphase, aka just  chilling. All it does here, is grow and replicate
  • 00:11:57
    all of its DNA, so that it actually has enough  genetic material and size to divide in M-Phase.
  • 00:12:02
    There’s multiple checkpoints in the cell  cycle which are controlled by proteins
  • 00:12:04
    like p53 or cyclin to check if the cell is  healthy and ready to reproduce. If a cell
  • 00:12:09
    is not quite right, it’s either fixed  or it destroys itself, which is called
  • 00:12:14
    “apoptosis”…or at least, that’s what it should do. Normal cells replicate until there’s no need to,
  • 00:12:18
    but some cells just keep going. This is because  they don’t respond correctly to these checkpoints
  • 00:12:22
    and end up replicating out of control and  functioning wrong, which is also known as cancer.
  • 00:12:27
    This damaging behaviour is often a result of a  gene mutation, which is a change somewhere in the
  • 00:12:31
    base sequence of a gene. This can happen during  DNA replication, when a single base is changed,
  • 00:12:36
    left out or inserted into the original sequence. This often changes the protein coded for by that
  • 00:12:41
    gene and let’s just say that  change is often not optimal.
  • 00:12:44
    Another type of mutation happens in chromosomes,  where entire sections of DNA could be duplicated,
  • 00:12:49
    deleted, flipped around or transferred between  chromosomes. The most famous chromosomal mutation
  • 00:12:53
    is probably when the 21st pair of chromosomes  has an additional copy, so that there’s 3
  • 00:12:58
    instead of 2. The result? Down syndrome. Mutations might seem like a bad thing,
  • 00:13:02
    but actually, they can also be neutral  or even beneficial. For example,
  • 00:13:05
    a species of yellow grasshoppers might  mutate and become green, which makes them
  • 00:13:08
    blend in with the grass and get eaten less. Over time, you can expect to see more and
  • 00:13:12
    more green grasshoppers, as their fitness  has increased. Not that kind of fitness,
  • 00:13:16
    fitness as in, they can have more  offspring, because they get eaten less.
  • 00:13:19
    This is natural selection and the driving  factor behind evolution, as the poorly adapted
  • 00:13:23
    species gets selected against and the fittest  species, which has adapted to the environment,
  • 00:13:27
    survives and and has the most offspring,  passing down the trait that made them survive.
  • 00:13:41
    If you think adaptation is cool, yes,  but also it kind of sucks. You see,
  • 00:13:45
    humans can get sick from bacteria or viruses,  but nowadays, we have medicine that works. Good!
  • 00:13:50
    However, what if the bacteria mutates and  suddenly, the medicine doesn’t work anymore? Well,
  • 00:13:54
    that’s kind of exactly what is happening,  aaand we have no clue how to fix it. So, yeah.
  • 00:13:59
    Oh yeah by the way, one thing many people confuse  is bacteria and viruses, and NO, they’re not the
  • 00:14:03
    same. Bacteria are prokaryotes, so they consist  of a single cell which can reproduce on its own,
  • 00:14:08
    and we treat bacterial infections such as  strep throat and tetanus with antibiotics.
  • 00:14:12
    Viruses are not made of cells, in fact,  we’re not even sure they’re alive. They
  • 00:14:16
    share some signs of life, but they can only  reproduce inside a host, and they don’t grow,
  • 00:14:20
    so it’s not really alive, but it’s not dead  either, it’s more of non-living kind of thing.
  • 00:14:25
    Also, you cannot treat viral infections with  antibiotics, most of the time you just have to
  • 00:14:29
    chill out and let your immune system do its thing. Now you might think bacteria are a bad thing, but
  • 00:14:33
    actually, you have millions good bacteria inside  your gut. The live in symbiosis with you, so you
  • 00:14:37
    give them food, and they help you digest it. Speaking of digestion, your body is made of
  • 00:14:41
    many complex organ systems that work  together to make sure you don’t die,
  • 00:14:45
    and I know what you’re thinking. Actually  I don’t, but I know how you’re thinking.
  • 00:14:49
    The nervous system, consisting of nerves,  which connect to the spinal cord and lead
  • 00:14:52
    to your brain, is made of cells called  “neurons” which can conduct electricity
  • 00:14:56
    along this long tube called the “axon”. Anything you see, think and feel, it’s
  • 00:15:00
    all just electrical signals going to your brain,  and your brain telling your body how to respond.
  • 00:15:04
    To be exact, the signals are called “action  potentials” and happen at the same strength
  • 00:15:08
    and the same speed every time, so  the only difference between “hey,
  • 00:15:11
    I’m a little cold” and “OMG I AM ON FIRE” is  where it happens and how frequent the signals are.
  • 00:15:16
    When a neuron is just chilling, the axon is  more negative on the inside than on the outside,
  • 00:15:20
    because there’s an unbalanced amount ions. This  causes an electric potential of about -70mV.
  • 00:15:25
    When there is a stimulus, signalling molecules  called neurotransmitters dock onto ion channels on
  • 00:15:30
    the axon and open them, letting the ions flow and  changing the electric potential around that area.
  • 00:15:34
    Now, action potentials are all or nothing.  A small stimulus won’t really do anything,
  • 00:15:38
    but, if the potential exceeds about  -55 mV, boom, action potential.
  • 00:15:43
    Ion channels around the stimulus  open and ions rush into the cell.
  • 00:15:46
    This causes the charge distribution in that  section of the axon to reverse for a split second,
  • 00:15:51
    which is called “depolarisation”. The ion channels that are next to
  • 00:15:54
    this area are influenced by this and open as well,
  • 00:15:56
    which causes a chain reaction and sends  the signal all the way down the axon.
  • 00:16:00
    Some neurons have a myelin sheath made  of Schwann cells, which insulate the
  • 00:16:03
    axon and only leave tiny gaps called nodes of  ranvier. If there’s a stimulus, the charges
  • 00:16:07
    can “jump” across the nodes which transmits  the signal way faster than a normal neuron.
  • 00:16:12
    But either way, at the bottom, the electric signal  reaches a terminal button, which connects the
  • 00:16:15
    current neuron to the dendrites of the next. If  you zoom in, you’d notice that the two cells don’t
  • 00:16:20
    even touch, there is actually a small gap. This  is once again where neurotransmitters come in:
  • 00:16:24
    Once the button is depolarized, tiny packages  of neurotransmitters get released, and bind
  • 00:16:28
    to receptors of following dendrite, either  blocking it from doing anything or causing
  • 00:16:32
    another action potential, which repeats the cycle. Hmmm. Something in my brain’s telling me that you
  • 00:16:37
    should definitely subscribe, and also, if you  want to stimulate your neurons and find out
  • 00:16:41
    how math is used in Biology, a resource I can’t  recommend enough is Brilliant, which has thousands
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    of interactive lessons for everything from basic  math to advanced data analysis and programming.
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    They use a hands-on approach so that instead  of memorizing formulas for hours on end,
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    you actually understand and remember what  you’re even learning. Not only that, but they
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    have plenty of real-life applications that you  can immediately apply the knowledge to, building
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    your problem-solving skills along the way. For example, their scientific thinking course
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    lets you interact with scientific principles  and theories, from simple machines like gears
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    and the physics behind playing snooker  all the way to Einstein’s special theory
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    of relativity...Sounds cool if you ask me. The best part? You can try everything they
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    have to offer for free for a full 30 days by  visiting brilliant.org/wackyscience. You’ll
  • 00:17:23
    also get 20% off an annual premium subscription.  Thanks to Brilliant for sponsoring this video!
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