ch. 4 | membrane structure & function

Question 1

(from 4.1)

what are integrated proteins?

Answer 1

proteins embedded in the plasma membrane of a cell

Question 2

(from 4.1)

what is the role of cholesterol (and other steroids) in a cell’s membrane?

Answer 2

stiffen & strengthen membrane

Question 3

(from 4.1)

what are peripheral proteins? what is one of their functions?

Answer 3

proteins on the inside of the plasma membrane; structural + help stabilize & shape membrane + help signal pathways btwn cells

Question 4

(from 4.1)

these integral proteins help molecules pass through the membrane via a channel which allows this to occur

Answer 4

channel proteins

Question 5

(from 4.1)

________ proteins help molecules pass through the plasma membrane via combining with a substance

Answer 5

carrier

Question 6

(from 4.1)

what are cell recognition proteins and what function do they carry out?

Answer 6

integral glycoproteins which help cells recognize and alert the body to pathogens (helps stimulate immune response)

Question 7

(from 4.1)

what are receptor proteins? what feauture of receptor proteins helps them carry out this function?

(what is a well-known example of a receptor protein?)

Answer 7

integral proteins which alert the cell to carry out certain functions; its shape after being binded with a specific molecule

(ans: insulin)

Question 8

(from 4.1)

which integral proteins carry out direct metabolic reactions within a cell?

Answer 8

enzymatic protein

Question 9

from 4.1

what are the respective cellular responses of these activated proteins:
a. structural protein
b. enzyme
c. gene regulatory protein

Answer 9

a. altered shape or movement of cell
b. altered metabolism or a function of cell
c. altered gene expression & amnt of a cell protein

Question 10

(from 4.2)

what are the special channel proteins which allow water to diffuse across the plasma membrane called?

Answer 10

aquaporins

Question 11

(from 4.2)

what is the difference between active and passive transport?

Answer 11

active = requires energy; passive = does not require energy

Question 12

(from 4.2)

what is the difference between diffusion and active transport of molecules into a cell’s membrane?

Answer 12

diffusion needs a concentration gradient & features molecules dispersing from a high concentration to a lower concentration; active transport requires a carrier protien + energy to move molecules from areas of low concentration to high concentration

Question 13

(from 4.2)

what is a isotonic solution? what happens due to the presence of this type of solution?

Answer 13

a solution cotaining an equal solute concentration to that of the cytoplasm of the cell; causes cells to neither gain nor lose water

Question 14

(from 4.2)

this type of solution contains a lower solute concentration than the cytoplasm of a cell

(also causes the cell to GAIN water via osmosis)

Answer 14

hypotonic solution

Question 15

this type of solution has a higher solute concentration than that within a cell’s cytoplasm

(causes a cell to LOSE water via osmosis)

Answer 15

hypertonic solution

Question 16

(from 4.2)

what happens during facilitated transport?

Answer 16

a carrier protein speeds the rate at which a solute crosses the plasma membrane toward the lower concentration within the cell’s cytoplasm

Question 17

(from 4.2)

what is the sodium-potassium pump? how does it affect the relationship of the inside of a cell to the outside of a cell?

Answer 17

a carrier protein that transports 3 sodium (Na+) ions outside of the cell and 2 potassium (K+) ions to the inside of the cell; causes the inside of the cell to be more negatively (less positively) charged than the outside

Question 18

(from 4.2)

how are macromolecules transported into and out of a cell? why?

Answer 18

via vesicle formation (also called bulk transport); too large for carrier proteins

Question 19

(from 4.2)

what do vesicles do during exocytosis?

(what also happens when the vesicle fuses with the plasma membrane?)

Answer 19

vesicles fuse w/ the plasma membrane to secrete hormones, neurotransmitters, & digestive enzymes

(vesicle membrane fuses permanently w/ plasma membrane–cell grows)

Question 20

(from 4.2)

when a large material is taken in by endocytosis (process of things entering the cell), this is called ____________.

(why is this important to an organism’s health?)

Answer 20

phagocytosis

ans: important in the development of immunity to bacterial diseases

Question 21

(from 4.2)

what occurs when vesicles (such as lysosomes) form around a liquid or very small particles?

(what is a function of this process?)

Answer 21

pinocytosis

Question 22

(from 4.2)

what happens during receptor-mediated endocytosis?

(why is this more effiicient than regular endocytosis?)

Answer 22

specific molecules bind to receptor proteins, shaped specific to the molecules that are then selectively taken into a cell via vacuole formation

ans: is involved both in the uptake & transfer/exchange of substances

Question 23

(from 4.3)

what is the extracellular matrix? (ECM)

Question 24

(from 4.3)

list the 3 types of cell junctions and their respective functions

Answer 24

• adhesion juntions = mechanically attach cells via filaments
• tight junctions = junctions between cells which bring them tighter, connecting plama membranes
• gap junctions = allow comm btwn cells

Question 25

(from 4.3)

the cytoplasm of living plant cells is connected by the ____________, numerous narrow, membrane-lined channels that pass through the cell wall

(footnote)

what structures in these channels allow the direct exchange of some mterials btwn adjacent plant cells + connect all the cells within a cell?

Answer 25

plasmodesma

(footnote)

cytoplasmic strands

Question 26

what is cytolysis?

which type of solution causes cytolysis?

Answer 26

the bursting of a cell due to osmotic imbalance

hypotonic (low solute, high water = water into cell)

Question 27

what make up the primary cell wall?

Answer 27

cellulose fibrils held together by noncellulose substances