2.1.5 biological membranes

Question 1

what are the components of the fluid mosaic model

Answer 1

phospholipid bilayer made of a hydrophilic phosphate head and hydrophobic fatty acid tails
cholesterol
extrinsic and intrinsic proteins
glycolipids and glycoproteins

Question 2

what does an extrinsic protein act as

Answer 2

mechanic support
cell receptors

Question 3

what does an intrinsic protein act as

Answer 3

acts as carrier/channel protein

Question 4

what does cholesterol do

Answer 4

regulates fluidity of membranes (less fluid at high temps)
prevents leakages

Question 5

what do glycoproteins and glycolipids do

Answer 5

act as receptors in cell signalling
allow cells to attach to eachother
antigens

Question 6

explain cell signalling

Answer 6

signal molecules fit to complementary receptor molecules on cell membranes
(drugs can block receptors as they mimic cell signal molecules)

Question 7

what is diffusion

Answer 7

movement of molecules from high to low concentration across a partially permeable membrane

Question 8

describe molecules that move by diffusion

Answer 8

small
non-polar
lipid soluble

Question 9

what is facilitated diffusion

Answer 9

when molecules are too large to use diffusion

Question 10

describe molecules that move by facilitated diffusion

Answer 10

large = carrier proteins
polar = channel proteins
water soluble

Question 11

what is osmosis

Answer 11

water moving from high to low water potential through a partially permeable membrane

Question 12

what is active transport

Answer 12

molecules go from high to low concentration against a concentration gradient through a carrier protein using ATP

Question 13

what is endocytosis

Answer 13

into the cell via the vesicle

Question 14

what is exocytosis

Answer 14

out of cell via vesicle

Question 15

what does hypotonic mean

Answer 15

low concentration outside cell leading to high water potential

Question 16

what happens to plant cells when the solution is hypotonic

Answer 16

go turgid

Question 17

what happens to animal cells when the solution is hypotonic

Answer 17

go through cell lysis

Question 18

what does isotonic mean

Answer 18

same concentration inside and outside

Question 19

what happens to plant cells when the solution is isotonic

Answer 19

goes flaccid

Question 20

what happens to animal cells when the solution is isotonic

Answer 20

stays at equilibrium

Question 21

what does hypertonic mean

Answer 21

high concentration outside cell means low water potential

Question 22

what happens to plant cells when the solution is hypertonic

Answer 22

gets plasmolysed

Question 23

what happens to animal cells when the solution is hypertonic

Answer 23

experiences cell crenation (shrivels)

Question 24

what are the factors affecting fluidity regulation

Answer 24

temperature = higher means more kinetic energy so more fluid
more cholesterol = less fluid
unsaturated fatty acids = more fluid
ethanol dissolves lipids

Question 25

what are the factors affecting diffusion

Answer 25

higher temperature = higher rate due to more kinetic energy
higher surface area = more molecules can diffuse at once
larger molecules = more resistance
larger concentration gradient = increases rate
larger diffusion pathway = decreases rate