Semester Exam: membrane functions/structures

Question 1

plasma membrane

Answer 1

lipid and protein bilayer, changing fluid mosaic

seperates intrecellular and extracellular fluid

Question 2

membrane lipids

Answer 2

phospholipids
glycolipids
cholesterol

Question 3

phospholipids

Answer 3

Phosphate heads: polar and hydrophilic

Fatty acid tails: nonpolar and hydrophobic

Question 4

glycolipids

Answer 4

Lipids with polar sugar groups on outer membrane surface

Question 5

cholesterol

Answer 5

Increases membrane stability and fluidity

Question 6

integral proteins

Answer 6

inserted in membrane, function transporting proteins, enzymes, or receptors

Question 7

peripheral proteins

Answer 7

loosely attached to integral proteins

Include filaments on intracellular surface and glycoproteins on extracellular surface

Question 8

peripheral proteins function

Answer 8

enzymes, motor proteins, support

Question 9

functions of membrane proteins

Answer 9

Transport
Receptors for signal transduction
Attachment to cytoskeleton and extracellular matrix

Question 10

membrane junctions three types

Answer 10

tight
desmosome
gap

Question 11

tight junctions

Answer 11

Impermeable junctions Prevent fluids and most molecules from moving between cells

Question 12

desmosomes

Answer 12

rivets that anchor cells together

Question 13

gap junctions

Answer 13

Transmembrane proteins form pores that allow small molecules to pass from cell to cell, communicating junctions

Question 14

passive transport

Answer 14

No cellular energy (ATP) required

Substance moves down its concentration gradient

Question 15

active transport

Answer 15

Energy (ATP) required

Occurs only in living cell membranes

Question 16

What determines whether or not a substance can passively permeate a membrane?

Answer 16

Lipid solubility of substance
Channels of appropriate size
Carrier proteins

Question 17

passive transport types

Answer 17

Simple diffusion
Carrier-mediated facilitated diffusion
Channel-mediated facilitated diffusion
Osmosis

Question 18

Simple Diffusion

Answer 18

Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through the phospholipid bilayer

Question 19

Facilitated Diffusion

Answer 19

Certain lipophobic molecules (e.g., glucose, amino acids, and ions) use carrier proteins or channel proteins

Question 20

both channel proteins and carrier proteins

Answer 20

Exhibit specificity (selectivity)
Are saturable; rate is determined by number of carriers or channels

Question 21

Facilitated Diffusion Using Carrier Proteins

Answer 21

Transmembrane integral proteins transport specific polar molecules (e.g., sugars and amino acids)
Binding of substrate causes shape change in carrier

Question 22

Aqueous channels formed by transmembrane proteins selectively transport

Answer 22

ions or water

Question 23

Facilitated Diffusion Using Channel Proteins two types

Answer 23

Leakage channels
Always open
Gated channels
Controlled by chemical or electrical signals

Question 24

osmosis

Answer 24

Movement of solvent (water) across a selectively permeable membrane

Question 25

Water diffuses through plasma membranes:

Answer 25

Through the lipid bilayer | Through water channels called aquaporins

Question 26

osmolarity

Answer 26

`The measure of total concentration of solute particles

Question 27

tonicity

Answer 27

The ability of a solution to cause a cell to shrink or swell

Question 28

Isotonic

Answer 28

A solution with the same solute concentration as that of the cytosol

Question 29

Hypertonic

Answer 29

A solution having greater solute concentration than that of the cytosol

Question 30

Hypotonic

Answer 30

A solution having lesser solute concentration than that of the cytosol

Question 31

cells in isotonic solution

Answer 31

Cells retain their normal size and shape in isotonic solutions (same solute/water concentration as inside cells; water moves in and out).

Question 32

cells in hypertonic solution

Answer 32

``` Cells lose water by osmosis and shrink in a hypertonic solution (outside contains a higher concentration of solutes than are present inside the cells) ```

Question 33

cells in hypotonic solution

Answer 33

``` Cells take on water by osmosis until they become bloated and burst (lyse) in a hypotonic solution (outside contains a lower concentration of solutes than are present in cells). ```

Question 34

Cotransport

Answer 34

always transports more than one substance at a time

Question 35

Symport system

Answer 35

Two substances transported in same direction

Question 36

antiport system

Answer 36

Two substances transported in opposite directions

Question 37

vesicular transport

Answer 37

Transport of large particles, macromolecules, and fluids across plasma membranes Requires ATP

Question 38

Exocytosis

Answer 38

out of cell

Question 39

endocytosis

Answer 39

into cell

Question 40

transcytosis

Answer 40

transport into,across, and then out of cell

Question 41

Phagocytosis

Answer 41

pseudopods engulf solids and bring them into cell’s interior | food, macrophages, white blood cell

Question 42

pinocytosis

Answer 42

bringing extracellular fluid and solutes into interior of the cell Nutrient absorption in the small intestine