Chapter 7 - Membrane & Structure Function

Question 1

what are amphipathic molecules (ex:phospholipids)

Answer 1

contains hydrophobic and hydrophilic regions

Question 2

the fluid mosaic model

Answer 2

the membrane structure depicted as a pmosaic of protein molecules, bobbing in a fluid bilayer of phospholipids.

Question 3

are proteins randomly distributed in the membrane?

Answer 3

no, they form groups

Question 4

membranes are held together by _ interactions

Answer 4

weak hydrophobic interactions

Question 5

unsaturated tails are fluid ->

Answer 5

they prevent packing

Question 6

saturated tails are viscous->

Answer 6

the tails pack together

Question 7

at lower temperatures, cholesterol ->

Answer 7

disrupts packing, hindering solidification

Question 8

peripheral proteins

Answer 8

proteins that are bound to the surface of the membrane

Question 9

integral proteins

Answer 9

proteins that penetrate the hydrophobic core

Question 10

a biological membrane is…

Answer 10

two layers of phospholipids with proteins either spanning the layers or on the surface of the layers (think of the fluid mosaic model)

Question 11

transmembrane proteins are…

Answer 11

integral proteins that span the membrane

Question 12

selective permeability

Answer 12

membranes may be selective, some substances cross more easily than others

Question 13

the movement of particles of any substance so that they spread out evenly into the available space

Answer 13

diffusion

Question 14

the diffusion of a substance across a biological membrane (no additional energy is required)

Answer 14

passive transport (does not need energy to cross membrane)

Question 15

what is osmosis ?

Answer 15

the diffusion of free water, across a selectively permeable membrane

Question 16

water molecules will diffuse in order to…

Answer 16

water molecules regulate the solute concentration on both sides (in the tube case, moves from lower concentration to higher concentration to balance)

Question 17

a hypotonic cell is

Answer 17

more water in the cell, appears bigger

Question 18

a isotonic cell is

Answer 18

normal balance of water going in and out, cell is normal

Question 19

a hypertonic cell is

Answer 19

lacks water, appears shriveled

Question 20

facilitated diffusion is…

Answer 20

passive transport aided by proteins

Question 21

channel proteins

Answer 21

type of protein that has a hydrophilic channel that can be used as a tunnel

Question 22

carrier proteins

Answer 22

a protein that BINDS to the molecules + changes shape to shuttle them across the membrane

Question 23

transport proteins are…

Answer 23

a type of protein that moves only specific substances (selective permeability depends on the specific type of transport protein)

Question 24

what is active transport?

Answer 24

using energy to move substances against their gradients

Question 25

all proteins in active transport are...

Answer 25

they are carrier proteins (they have to bind and change shape)

Question 26

facilitated diffusion is different from active transport because of...

Answer 26

F.D. goes along with the gradient (not require energy), active goes against (uses energy

Question 27

bulk transport

Answer 27

large molecules being transported by exocytosis and endocytosis

Question 28

in exocytosis

Answer 28

bulk transport, transport vesicles migrate to the membrane + fuse and export contents outside cell

Question 29

in endocytosis

Answer 29

macromolecules are taken into the cell, makes a pocket around it

Question 30

the three types of endocytosis

Answer 30

phagocytosis (eats + pocket), pinocytosis (drinks + coats, and receptor mediated (coated vesicle + binding to receptors)