cell transport mechanisms

Question 1

what is a fluid mosaic model ?

Answer 1

the fluidity of a membrane and the mosaic arrangement of the proteins give the structure of the membrane

Question 2

what is a glycoprotein ?

Answer 2

proteins with carbohydrate chains attached

Question 3

how can a glycoprotein act as a receptor ?

Answer 3

its carbohydrate chain binds to a molecule on the outside of the cell which causes a change in the shape of the tertiary structure and that triggers a a signal that passes through the cell

Question 4

what is a glycolipid ?

Answer 4

lipid with carbohydrate attached

Question 5

what does a glycolipids do ?

Answer 5

function in cell communication, stability, cell adhesion, and determining blood type

Question 6

what are the two functions to a glycoprotein ?

Answer 6

cell signaling and receptors

Question 7

how does cell signaling work ?

Answer 7

one cell releases a messenger molecule and this molecule travels to another cell the messenger molecule is detected by the cell as it binds to the receptor of the cell membrane

Question 8

what does cholesterol do ?

Answer 8

it fits between the phospholipid causing them to become more rigid and are packed closer together making the membrane less fluid

Question 9

what are the components of the phospholipid bi layer ?

Answer 9

hydrophobic tails and hydrophilic heads in a double layered arrangement with the hydrophobic tails facing inwards and and the hydrophilic tails facing outwards

Question 10

what components can diffuse through a cell membrane ?

Answer 10

small non polar molecules

Question 11

what four factors does the rat of diffusion depend on ?

Answer 11

concentration gradient - higher difference the faster it is
thickness of exchange surface - thinner it is ( less distance to travel the shorter it is
surface area -the larger the surface area the faster the rate of diffusion
temperature - warmer the temperature the faster the rate of diffusion because there more kinetic energy so more collisions

Question 12

how does temperature affect the structure of membranes

Answer 12

with increased temperature , there’s more kinetic energy which disrupts the phospholipids and that creates gaps and makes it more permeable

Question 13

factors affecting rate of diffusion

Answer 13

-the difference in concentrations
-the temperature
-surface area of membrane

Question 14

what is diffusion ?

Answer 14

the free passage of molecules from a region of their high conc to a region of low conc
passive - no energy
small, non polar, lipid soluble

Question 15

what are channel proteins ?

Answer 15

a protein that allow the transport of specific substances across a cell membrane

Question 16

what do carrier proteins do when ions bind to them to transport through the cell membrane ?

Answer 16

changes shape and requires energy

Question 17

what are two changes to the structure of a membrane that can increase the rate of diffusion through the cell ?

Answer 17

reduced thickness and larger surface area

Question 18

where do the cells get the energy to diffuse through a cell ?

Answer 18

does not rely on external energy instead relies on the energy created by the random movement of colliding particles

Question 19

what 2 things does active transport require ?

Answer 19

carrier proteins and energy

Question 20

how does a carrier protein work ?

Answer 20

changes shape once an ion binds to it in order for it to pass through

Question 21

endocytosis

Answer 21

movement of materials into cells - phagocytosis

Question 22

exocytosis

Answer 22

movement of materials out of cells - neurotransmitters

Question 23

what is the process of phagocytosis ?

Answer 23

surround pathogens
ingest them
take them to food vacuoles
digest them using enzymes in vacuoles

Question 24

why is facilitated diffusion not a form of active transport ?

Answer 24

it is a passive process and relies on the channel protein to transport the molecules through to the other side of the membrane

Question 25

what is co transport ?

Answer 25

when the transport of one substance is coupled with the transport of another substance across a membrane

Question 26

what is active transport ?

Answer 26

the movements of substances across a cell surface membrane against a conc gradient, using energy in the form of ATP

Question 27

what is osmosis ?

Answer 27

the net movement of water down a water potential gradient through a partially permeable membrane

Question 28

what is water potential measured in ?

Answer 28

PASCALS

Question 29

what does it mean if a solution is more concentrated ?

Answer 29

water molecules are less free to move

Question 30

when there are no dissolved solutes then does the water potential have a greater or lower potential to move ?

Answer 30

highest possible water potential

Question 31

what is the water potential of pure water ?

Answer 31

zero

Question 32

the more concentrated solution …

Answer 32

more negative water potential

Question 33

how is the greater negative water potential of a solution caused by ?

Answer 33

the solutes dissolved in it - osmotic potential

Question 34

what does the cell do as the turgor pressure is exerted by the plant cell wall ?

Answer 34

the cell takes in water tends to push water out of the cell and therefore would be labelled positive

Question 35

equation for water potential

Answer 35

turgor pressure + osmotic potential

Question 36

what happens to an animal cell when put in hypotonic solution ?

Answer 36

there will be a net movement of free water into the cell
- it will swell and burst (lysis) - no cell wall

Question 37

what happens to a plant cell when put in hypotonic solution ?

Answer 37

• it receives water by osmosis and swells
  it does not burst because it is surrounded by a rigid cell wall that can withstand the turgor pressure of the turgid cell contents

Question 38

what is hypotonic solution ?

Answer 38

where there is higher water potential outside of the cell

Question 39

what happens to an animal cell when put in isotonic solution ?

Answer 39

no net movement of water

Question 40

what happens to a plant cell when put in isotonic solution ?

Answer 40

cell will not shrink or swell, as there will not be any change in cells

Question 41

what is isotonic solution ?

Answer 41

equilibrium

Question 42

what happens to an animal cell when put in hypertonic solution ?

Answer 42

water flows out of the cell faster than it comes in - crenation (shriveling)

Question 43

what happens to a plant cell when put in hypertonic solution ?

Answer 43

water from inside the cells cytoplasm diffuses out

Question 44

what is hypertonic solution ?

Answer 44

higher water potential inside the cell

Question 45

Describe the structure of a cell membrane

Answer 45

• phospholipid bilayer which it consists of hydrophilic head facing outwards + hydrophobic tail facing inwards
• channel protein to transport molecules
• cholesterol to maintain fluidity
• glycoprotein acts a receptors to allow substances in and out

Question 46

suggest two properties of molecules that enable them to enter a cell by diffusion

Answer 46

small and non polar

Question 47

describe one similarity and one difference between facilitated diffusion and active transport

Answer 47

• both use channel and carrier proteins to transport molecules
• active transport uses energy