part 2

Question 1

Functions of the Plasma Membrane

Answer 1

-gatekeeper of the cell/selective barrier -defines boundaries of cell -controls what moves in and out -governs interaction with other cells

Question 2

The structures of the Plasma Membrane

Answer 2

-98% lipids —75% phospholipids (forms a bi-layer) —20% cholesterol —2% Proteins

Question 3

Transmembrane Proteins

Answer 3

penetrates into the phospholipid bi-layer

Question 4

Peripheral Proteins

Answer 4

adheres to intersurface of membrane

Question 5

Phospholipid

Answer 5

amphiphatic molecule that arrange themselves in a bi-layer with hydrophobic phospate containing heads facing outside of cell or inside -hydophobic tails are inside the cell to avoid H2O

Question 6

Receptor protein

Answer 6

a receptor that binds to chemical messengers such as hormones sent by other cells

Question 7

Enzyme (membrane protein)

Answer 7

an enzyme that breaks down as chemical messenger and terminates its effect

Question 8

Ion Channel

Answer 8

A channel protein that is constantly open and allows ions to pass into and out of the cell

Question 9

Gated Ion Channel

Answer 9

A gated channel that opens and closes to allow ions through only at certain times

Question 10

Cell-Identity marker

Answer 10

a glycoprotein acting as a cell-identity marker distinguishing the body’s own cells from foreign cells

Question 11

Why is plasma membrane a selective barrier?

Answer 11

Because of chemical and structural nature of phospholipid bi-layer. Hydrophobic core- only lipid soluble molecules and some small molecules are able to pass through

Question 12

What can pass through cell membrane?

Answer 12

Water and lipid soluble substances Gases

Question 13

What happens if large or charged molecules need to enter/exit?

Answer 13

Need a carrier or vesicle

Question 14

Types of Passive Transport:

Answer 14

DOESN’T NEED ENERGY filtration diffusion osmosis facilitated diffusion

Question 15

Types of Active Transport:

Answer 15

NEED ATP active transport endocytosis extocytosis

Question 16

Filtration:

Answer 16

-movement of materials between cells (NOT THROUGH MEMBRANE) -movement of water and solute molecules across the cell membrane due to hydrostatic pressure generated by the cardiovascular system. –Filtration is seen in blood capillaries where blood pressure forces fluid through gaps in capillary wall

Question 17

hydrostatic pressure

Answer 17

blood pressure with capillary vessels the pressure exerted

Question 18

Diffusion

Answer 18

movement of particles from higher concentration to lower concentration -movement until equilibrium is reached

Question 19

In passive transport, substances diffuse _________ their concentration gradient

Answer 19

Down

Question 20

Factors that affect diffusion rate

Answer 20

1. Temperature increase–> diffusion rate increase 2. Steepness of concentration gradient–> diffusion rate increases 3. Membrane surface are increase–> diffusion rate increases 4. Membrane permeability increases–> diffusion rate increases 5. Molecular weight increases–> diffusion rate decreases

Question 21

Facilitated Diffusion

Answer 21

for molecules that are too large to pass through membrane -requires a carrier -NO energy needed because substance moves down concentration gradient

Question 22

Osmosis

Answer 22

-net flow of H2O across membrane -from high [H2O] to low [H2O] or flow from low [solute] to a high [solute]