membrane

Question 1

what are the components of a cell membrane

Answer 1

phospholipid bilayer, proteins (integral and peripheral), carbohydrates (glycoprotein and glycolipid), cholesterol, extracellular and intercellular fluid.

Question 2

what arrangement is the membrane and why

Answer 2

fluid mosaic model because the bilayer can shift position (fluidity) and is embedded with other molecules (mosaic)

Question 3

hydrophilic and hydrophobic parts of the membrane

Answer 3

tails - phobic, heads - philic

Question 4

what is the bilayer made of

Answer 4

lipids (fats)

Question 5

what shapes have a larger SA:V

Answer 5

smaller and less spherical (flat)

Question 6

what is the cell membrane made out of

Answer 6

phospholipid bilayer, integral and peripheral proteins, channel proteins, glyco protein and glycolipids ( with carbohydrates), cholesterol

Question 7

what is a glycoprotein

Answer 7

the balls of carbohydrates are connected to a protein

Question 8

what is a glycolipid

Answer 8

the balls of carbohydrates are connected to a head

Question 9

inside and outside of cell

Answer 9

intercellular and extracellular fluid

Question 10

4 functions of the plasma membrane

Answer 10

1. allows substances in and out of the cell 2. provides a boundary around cell 3. prevents substances from entering the cell 4. holds all cell contents

Question 11

diffusion definition

Answer 11

the passive movement of particles from an area with higher concentration to an area with lower concentration

Question 12

when does diffusion stop

Answer 12

when equilibrium is reached after which no net movement will occur

Question 13

4 things that effect diffusion rates

Answer 13

molecular size, presence of net charge, solubility in liquid solvents, direction of concentration gradient

Question 14

how does molecular size impact diffusion

Answer 14

smaller molecules like water 3-5 atoms can easily pass through bigger like gluecose cannot

Question 15

how does net charge impact diffusion

Answer 15

uncharged and non-polar can diffuse freely but charged cannot as heads stop them

Question 16

how does solubility in lipid solvents impact diffusion

Answer 16

lipids and lipid soluble molecules can diffuse freely as they can combine with the tails

Question 17

direction of concentration gradient impact diffusion

Answer 17

molecules that can diffuse will go down the concentration gradient

Question 18

4 ways a substance can move across a membrane

Answer 18

simple diffusion and osmosis, facilitated diffusion, active transport and bulk transport

Question 19

what is facilitated diffusion

Answer 19

still passive and occurs with large molecules like gluecose using a channel or carrier protein

Question 20

what is osmosis

Answer 20

passive movement of water molecules from a higher water concentration and lower solute concentration to an area with a lower water and higher solute concentration across a semi-permeable membrane

Question 21

when does osmosis stop

Answer 21

when equilibrium is reached and there will be no further NET movement

Question 22

when a solution has a higher concentration of water

Answer 22

hypotonic

Question 23

when a solution has a higher concentration of solutes

Answer 23

hypertonic

Question 24

when a solution has a higher concentration of solutes

Answer 24

hypertonic

Question 25

when water moves from the solution inot the cell

Answer 25

cytolysis

Question 26

when a solution has a higher concentration of solutes than another

Answer 26

hypertonic

Question 27

when water moves out of the cell inot the solution

Answer 27

plasmolysis

Question 28

when the concentration of solutes is equal in the cell and solution

Answer 28

isotonic

Question 29

animal and plant cells when a solution is hypotonic

Answer 29

lysed and turgid (normal)

Question 30

animal and plant cells when a solution is hypertonic

Answer 30

shriveled and plasmolyzed

Question 31

animal and plant cells when a solution is isotonic

Answer 31

normal and flaccid

Question 32

active transport

Answer 32

movement of substances against the concentration gradient which requires the expenditure of energy in the form of ATP

Question 33

how are substances transported in active transport

Answer 33

integral proteins which act as 'carriers' or 'pumps'

Question 34

why is active transport needed

Answer 34

when there are big differences between internal and external concentrations or charged particles because they cannot diffuse through the membrane

Question 35

two types of bulk transport

Answer 35

exocytosis and endocytosis

Question 36

exocytosis

Answer 36

proteins are modified and packaged into vesicles by the golgi body and are sent out of the cell

Question 37

endocytosis

Answer 37

the vesticles are pinched of plasma membrane in either phagocytosis or pinocytosis

Question 38

phagocytosis

Answer 38

when solid matter is englufed

Question 39

pinocytosis

Answer 39

when substances engulfed are in solution

Question 40

what molecules can diffuse directly across the membrane

Answer 40

allows for passive diffusion of hydrophobic or non-polar molecules. These are either small in size or lipid soluble and pass through the gaps between the phospholipids. eg water, oxygen, carbon-dioxide, urea, alcohol.

Question 41

what substances cannot diffuse across the membrane freely

Answer 41

Water soluble, polar substances move across the membrane by diffusion or active transport, but this occurs through protein channels. eg amino acids, nucleic acids, carbohydrates, proteins and ions (see next slide)

Question 42

what allows the membrane to have a fluid nature

Answer 42

the presence of cholersterol

Question 43

what does cholersterol do in the membrane

Answer 43

Cholesterol also gives the membrane stability. It stops the membrane from being rigid when temperatures are low and from falling apart when temperatures are too high by reducing the permeability of small water-soluble molecules.