Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Module 2: Foundations in Biology > Biological membranes > Flashcards

Biological membranes Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what are membranes

A

partially permeable barriers that allow cell compartmentalisation, resulting in different conditions either side.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why are membranes defined as fluid mosaic

A
  • phospholipid molecules are constantly moving
  • embedded with proteins : glycoproteins (proteins that have a carbohydrate chain)
  • glycolipids: lipids that have a carbohydrate chain attached
  • cholesterol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

description of phospholipids in the plasma membrane

A
  • forms a bilayer: hydrophilic phosphate heads oriented towards water, hydrophilic fatty acid tails oriented inwards away from water
  • lipid-soluble substances can pass
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

role of proteins in plasma membrane

A

act as receptors, channels, carriers. Can support membrane and cytoskeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

role of cholesterol in plasma membrane

A
  • regulates membrane fluidity and provides strength by binding to hydrophobic tails causing them to pack closely together
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

role of glycoproteins/glycolipids

A
  • receptors for cell signalling
  • antigens
  • sites where drugs, hormones and antibodies can bind
  • they stabilise the membrane by forming H bonds with surrounding water molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

effect of low temp on plasma membrane

A
  • saturated fatty acids pack more closely together, reducing fluidity and increasing rigidity
  • counteracted by unsaturated fatty acids with kinks pushing phospholipids apart and cholesterol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

effect of high temp on plasma membrane

A
  • phospholipids gain more Ke and vibrate more, plasma membrane becomes more fluid and permeable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

role of plasma membranes

A
  • barrier between cell and its environment, controlling which substances enter or leave
  • allow recognition by other cells ( immune system)
  • allow cell communication (cell signalling)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

role of membranes within cells

A
  • membranes around organelles divide cells into compartments making different functions more efficient like substances needed for respiration being kept inside mitochondria
  • formation vesicles to transport substances
  • control which substances enter and leave organelle e.g. RNA leaves nucleus via nuclear membrane
  • site of chemical reactions like inner membrane of mitochondrion contains enzymes for respiration membranes within organelles act as barriers (thylakoid membrane in chloroplast)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

in which membranes is cholesterol not found in

A

bacterial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

effect of high temperature on cytoskeleton

A

proteins in it denature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how is permeability investigated

A
  • investigated using beetroots and solvents
    1. make a serial dilution of solvent using stock solution
    2. add beetroot different dilutions
    3. measure pigment released into solution from cells using a colorimeter calibrated with water
    4. record data and interpret results
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

effect of destroyed plasma membranes on light transmission in colorimetry

A

reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

define diffusion

A

the passive net movement of molecules from an area of higher conc to an area of lower conc down the conc gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

which type of molecules can enter the cell by simple diffusion via channel proteins

A

small and non-polar (CO2 and O2)

17
Q

which type of molecules require facilitates diffusion via carrier or channel proteins proteins and why

A
  • large and polar (aa, glucose)
  • polar/charged particles are water-soluble and are repelled by the hydrophobic tails of the phospholipids. Aquaporins enable transport
18
Q

what factors affect the rate of diffusion

A
  1. conc gradient - the higher it is, the higher the rate of diffusion
  2. thickness of exchange surface - thinner, shorter diffusion distance, faster rate
  3. surface area - larger, faster rate
  4. temperature - warmer, particles have more Ke so rate is faster
19
Q

define osmosis

A

the movement of water down a water potential gradient across a partially permeable membrane from an area of higher water pot to an area of lower water pot

20
Q

water potential of pure water

A

0kPa

21
Q

what happens to the water potential when solutes are added

A

it decreases

22
Q

what’s an isotonic solution

A

solution with higher water pot than the cell

23
Q

what’s an isotonic solution

A

solution with same water pot as the cell

24
Q

what’s a hypertonic solution

A

solution with a lower water pot than the cell

25
Q

what happens when an animal cell is placed in a hypotonic solution

A
  • net movement of water molecules is into the cell
  • cell bursts (cytolysis)
26
Q

what happens when an animal cell is placed in a isotonic solution

A
  • water moves into and out of cell in equal amounts
  • cell stays the same
27
Q

what happens when an animal cell is placed in a hypertonic solution

A
  • net movement of water is out of the cell
  • cell shrinks (crenation)
28
Q

what happens when an plant cell is placed in a hypotonic solution

A
  • net movement of water molecules is into the cell
  • vacuole swells causing the vacuole and cytoplasm to push against the cell wall
  • cell is turgid
29
Q

what happens when an plant cell is placed in a isotonic solution

A
  • water moves into and out of cell in equal amounts
  • cell stays the same
30
Q

what happens when an plant cell is placed in a hypertonic solution

A
  • net movement of water is out of the cell
  • cell becomes flaccid and the cytoplasm + membrane pull away from the cell wall
  • plasmolysis
31
Q

how can osmosis be investigated

A
  • by observing the size and shape of onion or cheek cells under a light microscope at different water potentials
32
Q

what can be used to demonstrate osmosis

A
  • potato cores
  • water potential of potato cores can be calculated using % change in mass of the cores at various known water potentials and plotting a graph
    1. set up test tubes of known water potentials by making serial dilutions of salt and water
    2. place potato cores of known mass into each solution
    3. after set time interval has passed, measure the new mass of potato core
33
Q

what does the point at which the graph meets the x axis show

A

potato had same water pot as solution

34
Q

define active transport

A
  • movement of particles into a cell from a region of low concentration to a region of higher concentration against the concentration gradient using ATP and carrier proteins
  • ATP is used to directly move particles, such as in the accumulation of ions in root hair cells
35
Q

outline active transport

A
  1. Particle binds to carrier protein with specific tertiary structure
  2. ATP binds to protein and is hydrolysed to ADP+Pi, releasing energy
  3. Protein undergoes a conformational change and carries particles to the other side of plasma membrane
  4. Process can be repeated as new ATP molecules replaces ADP+Pi and protein regains original shape
36
Q

what’s bulk transport

A
  • use of ATP to move large amounts of particles that are too big to cross via the membrane or carrier proteins
  • example: exocytosis, (pino)endocytosis
37
Q

how does endocytosis occur

A
  • the membrane encloses particles, the membrane pinches off to form a vesicle, such as in phagocytosis or pinocytosis (for liquids)
  • requires ATP
38
Q

how does exocytosis occur

A
  • internal vesicles pinch off from sacs of the Golgi apparatus and move towards plasma membrane via cytoskeleton then fuse with the membrane to release particles to the extracellular fluid such as at synapses
  • some substances like membrane proteins aren’t released but are inserted into plasma membrane
  • requires ATP

Module 2: Foundations in Biology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions