chapter 7🧪

Question 1

passive transport

Answer 1

doesn’t require energy and it may involve transport proteins

Question 2

active transport

Answer 2

requires energy and a transport protein

Question 3

bulk transport

Answer 3

moves large molecules

Question 4

phospholipids are blank which means

Answer 4

amphipathic which means it has a hydrophilic region and a hydrophobic region

Question 5

describe fluid mosaic model and what is it

Answer 5

its an accepted model of the plasma membrane
in the model the membrane is a mosaic of protein molecules bobbing in a fluid bilateral of phospholipids

Question 6

membrane fluidity

Answer 6

membranes are not static and locked in place. most of the lipids and some proteins can shift sideways(laterally)

rarely a lipid flip flop across the membrane switching from one phospholipid layer to another

Question 7

how does decreasing temp affect membrane fluidity

Answer 7

keeps membrane fluid

Question 8

how does phospholipids with unsaturated hydrocarbon chains affect membrane fluidity

Answer 8

the kinks in the tails don’t allow them to pack together as close a saturated fats, which makes them more fluid

Question 9

how does cholesterol affect membrane fluidity and where is it found

Answer 9

it acts as a buffer, resisting changes in membrane fluidity that are caused by changes in temp

at high temps it makes membrane less fluid by restricting phospholipid movement

it lowers temp required to solidify to hinder the close packing of phospholipids

cholesterol is found wedged between phospholipid molecules in the plasma membrane of animal cells

Question 10

how does increasing the number of saturated hydrocarbon tails affect membrane fluidity

Answer 10

makes membrane less fluid

Question 11

integral proteins

Answer 11

type of membrane protein penetrate the interior hydrophobic region of lipid bilayer

Question 12

peripheral proteins

Answer 12

don’t penetrate lipid bilayer they are loosely attached to the surface(hydrophilic region)

Question 13

what do the hydrophobic regions of integral proteins consist of

Answer 13

non polar amino acids

Question 14

glycolipids

Answer 14

membrane carbohydrates covalently bonded to lipids

Question 15

glycoproteins

Answer 15

membrane carbohydrates covalently bonded to proteins

Question 16

role of glycoproteins and glycolipids on cell surfaces

Answer 16

their diversity and location enables them to function as distinguishers of one cell from another

Question 17

ex of hydrophobic no polar molecules and do they pass through membrane easily

Answer 17

hydrocarbons, CO2, O2, lipids

they dissolve in the lipid bilayer of the membrane and cross it easily without help from membrane proteins

Question 18

polar hydrophilic substances ex and do they pass through easily

Answer 18

glucose, other sugars, and even water

they slowly pass through lipid bilayer

Question 19

polar hydrophilic substances avoid passing lipid by layer by

Answer 19

passing through transport proteins

Question 20

channel proteins

Answer 20

type of transport protein that function by having a hydrophilic channel that certain molecules/ions use as a tunnel through the membrane

Question 21

aquaporins

Answer 21

type of channel proteins that allow water to pass through the membrane

Question 22

carrier proteins

Answer 22

hold on to their passengers and change shape to shuttle them across the membrane

Question 23

diffusion

Answer 23

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

Question 24

concentration gradient

Answer 24

the region along which the density of a chemical substance increases or decreases

happens in the absence of other forces

Question 25

diffusion of a substance across a biological membrane is called

Answer 25

passive transport because it requires no energy

Question 26

what affects diffusion rate

Answer 26

membrane permeability

Question 27

osmosis

Answer 27

the movement of free water across a selectively permeable membrane

Question 28

tonicity

Answer 28

the ability of a surrounding solution to u a cell to gain or lose water

Question 29

what makes a solution isotonic and what happens to a cell in an isotonic solution

Answer 29

if it’s solute concentration is the same as that inside the cell

there is no net movement of water across the membrane and water diffuses across the membrane at the same rate in both directions

the volume of a cell without a cell wall is stable in an isotonic solution

Question 30

what makes a solution hypertonic and what happens to cells placed in hypertonic solution

Answer 30

if the solute concentration is greater than that inside the cell it’s hypertonic

cells without cell walls will lose water, shrivel, and likely die in hypertonic solution

Question 31

what makes a solution hypotonic and what happens to cells in hypotonic solution

Answer 31

if the solute concentration is less than that inside the cell it’s hypotonic

cells without cell walls will gain water, swell, and lyse(burst) in a hypotonic solution

Question 32

turgor pressure

Answer 32

the pressure exerted when the cell wall expands to much

Question 33

turgid

Answer 33

cell is very firm
this is the healthy state for most plant cells

happens when surrounded by hypotonic solution

Question 34

flaccid

Answer 34

cell becomes limp
the plant wilts

this happens when a cells surroundings are isotonic

Question 35

plasmolysis

Answer 35

when a plant cell is surrounded in hypertonic solution it loses water, shrinks, and likely dies

cell wall doesn’t help

Question 36

facilitated function

Answer 36

polar molecules diffuse passively with the help of transport proteins

Question 37

active transport allows

Answer 37

cells to maintain concentration gradients that differ from their surroundings

Question 38

membrane potential

Answer 38

the voltage across a membrane

Question 39

endocytosis

Answer 39

cell takes in molecules and by forming vesicles from the plasma membrane

Question 40

exocytosis

Answer 40

transport vesicles migrate to the membrane, fuse with it, and release their contents

many secretory cells use this to export their products

Question 41

types of endocytosis

Answer 41

phagocytosis(cellular eating)
pinocytosis(cellular drinking)
receptor-mediated endocytosis

Question 42

phagocytosis

Answer 42

a cell engulfs a particle in a vacuole

the vacuole fuses with a lysosome to digest the particle

type of endocytosis

Question 43

pinocytosis

Answer 43

molecules are taken up when extra cellular fluid is “gulped” into tiny vesicles

Question 44

receptor mediated endocytosis

Answer 44

binding of ligands(any molecule that binds specifically to a receptor site of another molecule) to receptors triggers vesicle information

Question 45

cell size

Answer 45

smaller cells have greater surface to volume ratio

Question 46

surface area:
total volume:
SA:VOL ratio:

Answer 46

height x width x number of sides

length x width x height

surface area divided by volume