membrane

Question 1

solute

Answer 1

the particles which are being dissolves e.g. sugar, salt

Question 2

solvent

Answer 2

the substance that does the dissolving. water is the universal solvent

Question 3

solution

Answer 3

the solute dissolved int eh solvent (mixture of the two)

Question 4

components of the phospholipid

Answer 4

has a phosphate head (hydrophilic, lipophobic)

and a fatty acid tail (hydrophobic, lipophilic)

Question 5

how does the bilayer form

Answer 5

the phospholipids in the bilayer have phosphate heads which are attracted to water and hydrophobic fatty acid tails which repel water. this attraction between the heads and tails and water causes the phospholipid bilayer to spontaneously fall into place due to the way the molecules naturally arrange themselves

Question 6

transmembrane

Answer 6

refers to proteins which are embedded within and span the plasma membrane but have parts exposed to the exterior and interior of the cells

Question 7

integral proteins

Answer 7

fundamental components of the plasma membrane which are embedded into the phospholipid bilayer

Question 8

peripheral proteins

Answer 8

are either anchored into the exterior of the plasma membrane through bonding of lipids or are indirectly associated with the plasma membrane through interactions with integral proteins in the membrane

Question 9

carrier proteins

Answer 9

carrier proteins allow ions to move across the membrane
they have a conformational change (they change shape)

specific in enabling one type of molecule to move across. after binding to it specific cargo molecule, the carrier protein undergoes a change in shape as it delivers it’s cargo to the other side of the plasma membrane

Question 10

hydrophobic

Answer 10

if a compound repels water it is said to be hydrophobic, non polar

Question 11

hydrophilic

Answer 11

If a compound is attracted to water it is said to be hydrophilic, polar

Question 12

the fluid mosaic model

Answer 12

the plasma membrane contains many molecules (mosaic). the plasma membrane is fluid and flexible meaning molecules are not fixed in place. they can move through the membrane

Question 13

diffusion

Answer 13

the passive net movement of a substance from a region of high concentration to a region of low concentration

Question 14

what can cross the membrane

Answer 14

non polar, small lipophilic molecules can pass through the membrane. e.g. oxygen, CO2, alcohol

Question 15

facilitated diffusion

diffusion with help!

Answer 15

the passive net movement of a substance from a region of a high concentration to a region of low concentration, through a membrane via a specific channel or carrier protein.

Question 16

what characteristic require facilitated diffusion

Answer 16

Polar
large
lipophobic molecules
e.g. sodium, chloride, potassium, glucose

Question 17

osmosis

Answer 17

the net movement of water from an area of low solute concentration to an area of high solute concentration across a semipermeable membrane

Question 18

hypertonic

Answer 18

a solution that has a higher solute concentration than another

Question 19

hypotonic solution

Answer 19

a solution that has a lower solute concentration than another

Question 20

isotonic solution

Answer 20

two solutions containing the same concentrations of solutes

Question 21

active transport

Answer 21

the movement of molecules against the concentration gradient using the energy required by ATP
from an area of low concentration to an area of Hugh concentration

Question 22

endocytosis

Answer 22

the bulk movement of solids or liquids into the cell by englufment
phagocytosis is solids
pinocytosis is bulk movement of liquids

Question 23

exocytosis

Answer 23

movement of materials out of the cell via vesicles in the cytoplasm

Question 24

four factors which affect which substances can pass through the membrane

Answer 24

1. molecular size: small molecules can pass, macro molecules (nucleic acids) can’t
2. presence of a net charge: uncharged molecules can pass, charged cannot
3. solubility in lipid solvents: lipophobic (hydrophilic) can’t cross easily, lipophilic (hydrophobic) can
4. direction of concentration gradient. down the gradient does not require energy, movement against cannot occur by diffusion

Question 25

functions of the plasma membrane

Answer 25

1. is an active and selective boundary
2. denotes cell identity
3. receives external signals
4. transport materials

Question 26

glycolipid

Answer 26

acts as a surface receptor and stabilised the membrane. also has the role in helping cells aggregate in the formation of tissues

Question 27

cholesterol

Answer 27

located in the membrane, distributing the close packing of the phospholipids and its role is to keep the membrane more fluid

Question 28

glycoprotein

Answer 28

play an important role in cellular recognition and immune responses. they help stabilise the membrane structure. it is attached to the exposed part of the transmembrane protein