Cell Transport and Solutions

00:07:26
https://www.youtube.com/watch?v=-l-KaBtqLU8

Résumé

TLDRThe video discusses cell transport and solutions, focusing on how the concentration gradient of extracellular solutions affects cell membrane transport. It explains hypertonic, isotonic, and hypotonic solutions and their impact on cells. A hypertonic solution, with higher solute concentration outside, causes cells to lose water and shrivel. An isotonic solution, with equal solute concentrations inside and outside, maintains cell size through equal water movement in and out. A hypotonic solution, with higher water concentration outside, causes cells to absorb water and swell. Key concepts like osmosis, crenation, plasmolysis, and cytolysis are explained.

A retenir

  • 🔹 Hypertonic solutions cause cells to lose water and shrivel.
  • 🔹 Isotonic solutions maintain cell size with equal water movement.
  • 🔹 Hypotonic solutions make cells absorb water and swell.
  • 🔹 Osmosis is the diffusion of water across the cell membrane.
  • 🔹 Crenation occurs in red blood cells in hypertonic solutions.
  • 🔹 Plasmolysis causes plant cells to wilt in hypertonic solutions.
  • 🔹 Cytolysis can cause cell bursting in hypotonic solutions.
  • 🔹 Isotonic solutions result in no net water movement across membranes.
  • 🔹 Solute concentration affects water movement in and out of cells.
  • 🔹 Proper balance of solute and water is essential for cell health.

Chronologie

  • 00:00:00 - 00:07:26

    The video explores cell transport and solutions, focusing on how the concentration gradient of extracellular solutions influences substance transport through the cell membrane. It describes how cells interact with hypertonic, isotonic, and hypotonic solutions, affecting cell size and function. In hypertonic solutions, cells lose water and may shrivel (crenation in red blood cells or plasmolysis in plants). In isotonic solutions, water movement is balanced, so cell size remains unchanged. Meanwhile, hypotonic solutions cause cells to gain water, potentially leading to swelling or bursting (cytolysis, or hemolysis in red blood cells). Plant cells resist bursting due to rigid cell walls.

Carte mentale

Vidéo Q&R

  • What is a hypertonic solution?

    A hypertonic solution has a lower concentration of water and a higher concentration of solute compared to inside the cell, causing water to leave the cell, making it shrivel.

  • What happens to a cell in an isotonic solution?

    In an isotonic solution, the solute concentration is equal inside and outside the cell, resulting in equal water movement, keeping the cell size constant.

  • How does a hypotonic solution affect a cell?

    A hypotonic solution, with higher water concentration outside, causes water to flow into the cell, making it swell and potentially burst.

  • What is osmosis?

    Osmosis is the diffusion of water across a cell membrane from an area of higher concentration to an area of lower concentration.

  • Why do plant cells not burst in hypotonic solutions?

    Plant cells have rigid cell walls that prevent them from bursting even when they swell in hypotonic solutions.

  • What is plasmolysis?

    Plasmolysis is the process where plant cells lose water in a hypertonic solution, causing the cell membrane to shrink away from the cell wall, leading to wilting.

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Sous-titres
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Défilement automatique:
  • 00:00:05
    in this video we'll discuss cell
  • 00:00:07
    transport and solutions
  • 00:00:11
    the concentration gradient of
  • 00:00:13
    extracellular solutions affects the
  • 00:00:15
    transport of substances through the cell
  • 00:00:17
    membrane
  • 00:00:19
    what can happen in this process
  • 00:00:22
    well cells may be surrounded by
  • 00:00:24
    solutions with different particle
  • 00:00:25
    concentrations both in a lab as well as
  • 00:00:28
    inside a living organism
  • 00:00:30
    so we need to know how cells will
  • 00:00:32
    respond
  • 00:00:33
    compared to the solution inside a cell a
  • 00:00:36
    solution outside the cell may be
  • 00:00:39
    hypertonic
  • 00:00:40
    isotonic
  • 00:00:41
    or hypotonic
  • 00:00:44
    we'll describe hypertonic solutions
  • 00:00:46
    using this beaker of water with
  • 00:00:48
    dissolved salt and a rather large cell
  • 00:00:51
    submerged in it
  • 00:00:52
    to demonstrate water movement in and out
  • 00:00:55
    of cells we'll use simple numbers to
  • 00:00:57
    illustrate concepts
  • 00:00:59
    remember the cell cytoplasm is mostly
  • 00:01:01
    water as well
  • 00:01:02
    in this example let's say the cytoplasm
  • 00:01:05
    inside the cell is a solution containing
  • 00:01:08
    10 percent salt which means the other 90
  • 00:01:10
    percent is water
  • 00:01:12
    keep in mind percentages of substances
  • 00:01:14
    within the cell must equal one hundred
  • 00:01:17
    percent
  • 00:01:18
    the percentages of solute and solvent in
  • 00:01:21
    the beaker must also add up to one
  • 00:01:23
    hundred percent
  • 00:01:25
    however the solution in the beaker is a
  • 00:01:27
    different concentration from the
  • 00:01:29
    solution inside the cell
  • 00:01:31
    it's 20 salt and 80 percent water
  • 00:01:35
    so you can see that there's a greater
  • 00:01:37
    concentration of water inside the cell
  • 00:01:39
    than outside ninety percent compared to
  • 00:01:42
    eighty percent
  • 00:01:45
    we call a solution hypertonic when its
  • 00:01:47
    concentration of water is lower than
  • 00:01:50
    inside the cell and its concentration of
  • 00:01:52
    solute is higher than inside the cell
  • 00:01:56
    as a result water molecules diffuse out
  • 00:01:58
    of the cell through osmosis causing the
  • 00:02:00
    cell to shrivel a bit
  • 00:02:03
    remember osmosis means diffusion of
  • 00:02:05
    water
  • 00:02:07
    if the solution's water concentration
  • 00:02:09
    was significantly lower the cell could
  • 00:02:12
    shrivel to the point of imploding
  • 00:02:16
    for red blood cells in hypertonic
  • 00:02:18
    solutions the shriveling from osmotic
  • 00:02:20
    water loss is called crenation
  • 00:02:25
    let's look at an example of plant cells
  • 00:02:27
    in a hypertonic solution
  • 00:02:29
    normally turgor pressure which is the
  • 00:02:32
    water pressure in a plant cell's central
  • 00:02:34
    vacuole helps support the cell wall and
  • 00:02:37
    overall plant shape
  • 00:02:39
    when water leaves plant cells by osmosis
  • 00:02:41
    the cell membrane and its contents
  • 00:02:44
    shrink away from the rigid cell wall and
  • 00:02:47
    turgor pressure decreases
  • 00:02:49
    this is called plasmolysis
  • 00:02:52
    plasmolysis causes a plant to wilt
  • 00:02:57
    let's look at another container this
  • 00:02:59
    time with a cell floating in an isotonic
  • 00:03:01
    solution
  • 00:03:03
    sometimes
  • 00:03:04
    the solution outside the cell has about
  • 00:03:07
    the same concentration gradient as the
  • 00:03:09
    concentration gradient inside the cell
  • 00:03:13
    once again in this example the solution
  • 00:03:16
    inside the cell is ninety percent water
  • 00:03:18
    with ten percent salt
  • 00:03:20
    but this time the surrounding solution
  • 00:03:23
    is also ninety percent water with ten
  • 00:03:25
    percent salt dissolved
  • 00:03:29
    we call a solution isotonic when its
  • 00:03:32
    concentrations of water and solute are
  • 00:03:34
    the same as inside the cell
  • 00:03:38
    but this doesn't mean that there is no
  • 00:03:40
    movement
  • 00:03:42
    in an isotonic solution the rate of
  • 00:03:44
    water molecules entering the cell is
  • 00:03:46
    equal to the rate of water molecules
  • 00:03:48
    exiting the cell
  • 00:03:50
    the amount of water molecules going in
  • 00:03:52
    equals the amount of water molecules
  • 00:03:54
    going out
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    that's why you see the arrows pointing
  • 00:03:58
    in two different directions
  • 00:04:01
    in an isotonic solution the cell doesn't
  • 00:04:04
    shrink or swell it stays exactly the
  • 00:04:07
    same size
  • 00:04:09
    a third possibility is a solution
  • 00:04:11
    outside the cell with a higher
  • 00:04:13
    concentration of water than the solution
  • 00:04:15
    inside the cell
  • 00:04:17
    in this example the solution inside the
  • 00:04:20
    cell has 20 salt so that means the
  • 00:04:23
    remainder is 80 percent water
  • 00:04:26
    but the cell has been placed in a beaker
  • 00:04:28
    that only has a 10 salt solution
  • 00:04:32
    doing the math we can see that the
  • 00:04:34
    solution surrounding the cell is 90
  • 00:04:36
    water which means there's a greater
  • 00:04:39
    concentration of water outside the cell
  • 00:04:41
    than inside
  • 00:04:43
    we call a solution hypotonic when its
  • 00:04:45
    concentration of water is higher than
  • 00:04:48
    inside the cell and its concentration of
  • 00:04:50
    solute is lower than inside the cell
  • 00:04:53
    so by osmosis the water molecules will
  • 00:04:55
    move passively into the cell until a
  • 00:04:58
    state of equilibrium is reached
  • 00:05:01
    hypotonic solutions cause a cell to
  • 00:05:03
    swell up with water
  • 00:05:05
    if the water concentration outside the
  • 00:05:08
    cell is high enough the cell can swell
  • 00:05:10
    to the point of bursting
  • 00:05:12
    this is called cytosis
  • 00:05:17
    cytosis in red blood cells is called
  • 00:05:20
    hemolysis
  • 00:05:23
    cytolysis doesn't happen in plant cells
  • 00:05:25
    because the rigid cell wall prevents the
  • 00:05:28
    cells from bursting
  • 00:05:32
    here's a little trick to remember that
  • 00:05:34
    hypotonic solutions cause a cell to
  • 00:05:36
    swell rather than shrivel when you think
  • 00:05:38
    of hypo think of a big swollen
  • 00:05:41
    hippopotamus or hippo for short
  • 00:05:46
    so to recap we can have solutions that
  • 00:05:48
    are hypertonic isotonic or hypotonic
  • 00:05:51
    with respect to the cell
  • 00:05:53
    in an isotonic solution the water
  • 00:05:55
    concentration inside and outside the
  • 00:05:58
    cell stays about the same the water
  • 00:06:00
    concentration stays the same because the
  • 00:06:03
    concentration of solute is the same
  • 00:06:05
    as a result there's equal movement of
  • 00:06:07
    water in and out of the cell so the size
  • 00:06:10
    of the cell stays the same
  • 00:06:13
    here's a hypotonic solution
  • 00:06:16
    remember this means that there is a
  • 00:06:17
    lower concentration of solute outside
  • 00:06:20
    the cell compared to inside the cell
  • 00:06:23
    this causes water molecules to diffuse
  • 00:06:25
    into the cell remember when diffusion
  • 00:06:28
    happens with water we call that osmosis
  • 00:06:33
    this causes the cell to swell
  • 00:06:36
    if the concentration difference is high
  • 00:06:38
    enough cytolysis may occur
  • 00:06:41
    finally in a hypertonic solution the
  • 00:06:44
    solute concentration outside the cell is
  • 00:06:47
    higher compared to inside the cell
  • 00:06:50
    so through osmosis water molecules
  • 00:06:52
    diffuse out of the cell
  • 00:06:55
    this causes the cell to shrivel up and
  • 00:06:58
    it can even implode or collapse if
  • 00:07:01
    enough water leaves
  • 00:07:04
    in plants this cell collapse is called
  • 00:07:06
    plasmolysis
  • 00:07:10
    [Music]
  • 00:07:26
    you
Tags
  • cell transport
  • concentration gradient
  • hypertonic
  • isotonic
  • hypotonic
  • osmosis
  • plasmolysis
  • cytolysis
  • red blood cells
  • turgor pressure