Membrane Function

Question 1

what are the basic membrane functions?

Answer 1

• maintain internal cell environment at a steady state regardless of changes in the external environment
• acts a selective barrier regulating the movement of substances into and out of the cell

Question 2

what are the 3 main types of transport?

Answer 2

passive
active
bulk membrane

Question 3

what are the types of passive transport

Answer 3

simple duffusion
facilitated diffusion (channel, carrier)
osmosis

Question 4

what is the type of active transport

Answer 4

pump

Question 5

types of bulk membrane transport

Answer 5

• endosytosis
• exocytosis

Question 6

diffusion

Answer 6

substance spreads out since molecules are constantly in motion and bumping into each other

Question 7

passive transport definition

Answer 7

does not require energy and molecules move from high to low concentration

Question 8

simple diffusion/transfer

Answer 8

movement accross a semi-permeable membrane, down a concetration gradient, no energy required, continues until equilibrium is achieved

Question 9

what type of molecules go through simple diffusion?

Answer 9

O2 and CO2

Question 10

facilitated transport

Answer 10

across a semi permeable membrane passive transport, continues until equilibrium is achieve, moves through a channel or carrier proteins

Question 11

what types of particles go through channel proteins

Answer 11

small dissolved charged molecules like ions

Question 12

aquaporins

Answer 12

a specific type of channel protein that facilitate the movement of water molecules across a membrane

Question 13

carrier proteins

Answer 13

acts like turnstile/revolving door, underoges conformational change to allow molecules through

Question 14

types of particles through carrier proteins

Answer 14

moves a variety of substnaces from charged particles to large uncharged molecules

Question 15

uniport

Answer 15

movement of a single molecule in one direction - all channel proteins

Question 16

symport

Answer 16

movement of 2 molecules in the same direction

Question 17

antiport

Answer 17

movement of 2 molecules in opposite directions

Question 18

osmosis

Answer 18

diffusion of water

Question 19

describe osmosis

Answer 19

water moves from an area of high water concentration to an area of low water concentration

Question 20

tonicity

Answer 20

the concentration of solutes in the environment surrounding the cell

Question 21

isotonic

Answer 21

the same - equal movement in and out of cell

Question 22

hypotonic

Answer 22

less concentration of solutes outside the cell

Question 23

hypertonic

Answer 23

concentration of solutes is more outside the cell

Question 24

osmotic lysis

Answer 24

animal cell bursts

Question 25

hypertonic red blood cell

Answer 25

crenation

Question 26

isotonic red blood cell

Answer 26

equilibrium

Question 27

hypotonic red blood cell

Answer 27

hemolysis

Question 28

plant cell in isotonic environment

Answer 28

flaccid - lacking firmness (equilibrium) water movement unable to provide cell with internal pressure necessary for structural support

Question 29

plant cell in hypotonic environment

Answer 29

rigid cell wall prevents plant cell from rupturing high presure to provide structural stability

Question 30

turgor pressure

Answer 30

increrased internal pressure due to water entry provides structural support for plant

Question 31

tugidity

Answer 31

cell swelling

Question 32

plasmolysis

Answer 32

shrinking of plasma membrane and cytoplasm away from cell wall

Question 33

plant cell in hypertonic environment

Answer 33

water moves out of cell, cell wall maintains its shape but cell membrane and cytoplasm shrinks

Question 34

turgid plant

Answer 34

hypotonic solution

Question 35

isotonic solution

Answer 35

flaccid

Question 36

plasmolyzed

Answer 36

hypertonic solution

Question 37

active transport

Answer 37

movement against concentration gradient - low to high

Question 38

what does active transport require?

Answer 38

energy in the form of ATP and a transport protein called a pump

Question 39

what does ATP do in active transport

Answer 39

indices a conformational change in the protein pump to allow specific molecules to enter/exit cell against its concentration gradient

Question 40

what types of molecules does nulk membrane transport move?

Answer 40

transport of molecules in large quantity too large or too polar to pass through the membrane, onvolves the folding of the cell membrane to form a vesicle

Question 41

types of endocytosis

Answer 41

pinocytosis phagocytosis receptor mediated endocytosis

Question 42

phagocytosis

Answer 42

process by which living cells ingest other cells or large particles

Question 43

when does phagocytosis happen

Answer 43

found in simpler forms of life for feeding (like amoebas) used in higher order organisms as a defense mecahnism against invasion by foreign particles

Question 44

phagocyte

Answer 44

a white blood cell specialized for protecting the body by ingesting foreign substances

Question 45

describe the mechanism of phagocytosis

Answer 45

- cell engulfs a particle by wrapping a psudopodia around it - enclosed in a large enough sac to be classified as a vacuole called a phagosome - hydrolytic enzymes in the lysosome digest the particle - residual body contains indigestible material which is eventually discharged by exocytosis

Question 46

lysosome

Answer 46

membrane bound sac of hydrolytic enzymes

Question 47

what pH does the lysosome enzyme work at best?

Answer 47

at pH 5

Question 48

how does the lysosome enzyme maindain acidic pH

Answer 48

pumps h+ into the lumen

Question 49

lysosome function is phagocytosis

Answer 49

- fuse with food vacuole to digest food (like stomach in animals) - fuses iwth phagosome to breakdown microorganisms

Question 50

autophagy

Answer 50

lysosome recycles cell's own organic material

Question 51

pinocytosis

Answer 51

ingestion of dissolved materials - "cellular drinking" cell folds inwards to take in fluild containing the desired substance

Question 52

ingavinates

Answer 52

cell folds inwards to take in fluid

Question 53

ligand

Answer 53

a molecule that binds to a receptor

Question 54

receprot-mediated endocytosis

Answer 54

intake of molecules that bind specifically to a receptor on the surface of the cell

Question 55

where are receptor proteins usually found?

Answer 55

clustered in regions of the membrane called coated pits which contain coat proteins that help form vesicles for endocytosis

Question 56

describe the mechanism of receptor-mediated endocytosis

Answer 56

- ligands bind to receptor - memrbane pinches to form vesicle - ligand detaches from receptor - vesicle pinch into 2 parts: free ligand and empty receptor - ligands fuse with lysosome - receptors returned to cell surface

Question 57

exocytosis

Answer 57

movement of materials from the cell to the cell surface within membrane bound vesicles

Question 58

how are the vesicles formed

Answer 58

off the golgi body of from endocytosis

Question 59

exocytosis function

Answer 59

- secretion (release of waste, toxins, signaling molecules) - recycling of membrane proteins - restoring the cell memrbrane