transport across membranes

Question 1

why the FMM called fluid

Answer 1

the phospholipid molecules form double layer that are constantly moving around relative to one another , giving the membrane a fluid structure

Question 2

why is the FMM called a mosaic

Answer 2

the protein are unevenly distrubed throughout the membrane so it is a mosaic

Question 3

what’s within the cell membrane:

Answer 3

aqaporins
cholesterol
channel proteins
carrier proteins
enzymes
glycoproteins
phospholipids
receptor proteins

Question 4

phospholipid function

Answer 4

-hydrophobic tails
-hydrophilic heads
-bilayer allows lipid-soluble molecules to pass through by simple diffusion
-prevents the passage of small polar molecules

Question 5

cholesterol functions

Answer 5

decreases permeability and increases stability of the membrane
more cholesterol = less fluid

Question 6

channel proteins functions

Answer 6

allow small molecules move across the membrane by facilitated diffusion
specific ions pass through specific channel proteins

Question 7

carrier proteins function

Answer 7

transport of ions and large molecules
by facilitated diffusuon and active transport

Question 8

receptor proteins functions

Answer 8

proteins act as specific receptors for complementary molecules eg. insulin to insulin receptor proteins

Question 9

enzymes functions

Answer 9

complementary to substrates, form ESC

Question 10

glycoproteins functions

Answer 10

carbs and proteins
outer surface of membrane
important in cell recognition, acts as antigens
produced in the golgi body

Question 11

aquaporins functions

Answer 11

special channel proteins
specific to water
lots of aquaporins means permeable to water and carry out osmosis easily

Question 12

diffusion definition

Answer 12

net movement of molecules from an area of higher concentration to a lower concentration across a partially permeable membrane

Question 13

fick’s law

Answer 13

rate of diffusion= (surface area x concentration gradient)/ diffusion distance

Question 14

factors affecting rate of diffusion

Answer 14

surface area
concentration gradient
diffusion distance
temperature

Question 15

how does surface area affect the ROD

Answer 15

larger SA allows more space for molecules to pass through SO faster

Question 16

how does temperature affect the ROD

Answer 16

increases kinetic energy SO faster

Question 17

how does the concentration gradient affect the ROD

Answer 17

as concentration difference increases, ROD increases

Question 18

how does diffusion distance affect ROD

Answer 18

shorter the distance, fewere membranes to cross SO molecules wil travel faster

Question 19

facilitated diffusion definition

Answer 19

specific proteins aid specific molecules to pass through

Question 20

is facilitated diffusion an active or passive process

Answer 20

passive
does not require ATP

Question 21

when does facilitated diffusion plateau on a graph

Answer 21

when all the carrier proteins are saturated
number of proteins is a limiting factor

Question 22

osmosis definition

Answer 22

net movement of water molecules from a high water potential to a lower water potential through a partially permeable membrane

Question 23

Active transport definition

Answer 23

-transport of molecules against their concentration gradient
-low to high
-only uses carrier proteins

Question 24

is active transport an active or passive process

Answer 24

it is active
requires ATP for a source of energy

Question 25

Exocytosis

Answer 25

-use golgi vesicles to transport large quantities of molecules from inside the cell to outside the cell
-used to move enzymes and glycoproteins fro golgi apparatus to cell surface membrane

Question 26

is exocytosis an active or passive process

Answer 26

active
it requires ATP to move the vesicles to the cell surface membrane and the vesicle fuse with the membrane

Question 27

Endocytosis

Answer 27

cell surface membrane is pulled inwards to create a vesicle
any molecules nearby are enclosed into the vesicle

Question 28

is endocytosis an active or passive process

Answer 28

active
requires ATP to create the vesicle and move the vesicle

Question 29

Many different substances enter and leave a cell by crossing its cell surface membrane.

Describe how substances can cross a cell surface membrane.

Answer 29

1. Small molecules pass via phospholipid bilayer
2. Large molecules go through proteins via facilitated diffusion from high to low concentration
3. Water moves by osmosis from higher water potential to lower water potential;
4. Active transport is movement from low to high concentration against the concentration gradient;
5. Active transport requires carrier proteins
6. Active transport requires ATP
7. NA+/glucose is