Bio 3 Exam 1

Front 1

In which of the following locations might a protein that enters the lumen of the endoplasmic reticulum also be found?

Back 1

Outside the cell

Front 2

Which of the following best explains why the plasma membranes of all cells exhibit a negative resting potential?

Back 2

The membrane is mostly permeable to K+, and the K+ gradient favors its diffusion out of the cell.

Front 3

What is the difference between passive diffusion and Osmosis?

Back 3

Osmosis is the diffusion of WATER across a selectively permeable membrane and passive diffusion transports substances (like proteins) across the cell

Front 4

The amino acids that would be expected to be located within the interior of a folded protein suspended in an aqueous buffer

Back 4

Isoleucine

Front 5

The covalent bonds between H and O in a water molecule are polar because:

Back 5

O is more electronegative than H

Front 6

A molecule that releases hydrogen ion when added to a solution (thus raising the hydrogen ion concentration of the solution and lowering the pH) is called:

Back 6

An acid

Front 7

What is the name of the molecule that steers proteins along productive folding pathways, helping them to fold correctly and preventing them from forming aggregates inside the cell?

Back 7

Chaperon proteins

Front 8

The tails of phospholipids are:

Back 8

Hydrophobic

Front 9

Why do lipids form bilayers in water?

Back 9

because the have hydrophilic heads and hydrophobic tails

Front 10

In a lipid bilayer, which behave like a two-dimensional fluid, lipid rapidly diffuse:

Back 10

within the plane of one monolayer in the bilayer + back and forth from one monolayer to the other in the bilayer

Front 11

Phospholipids with which of the following hydrocarbon tails will produce the most fluid bilayer?

Back 11

Tails with 18 carbon atoms, and two double bonds

Front 12

Margarine is made from vegetable oils in which the hydrocarbon tails have had what treatment?

Back 12

The removal of double bonds (changing them to single bonds and adding hydrogen atoms)

Front 13

Double bonds in hydrocarbon tails have what effect on the rigidity of fats and phospholipid bilayers?

Back 13

It will make it more fluid, less compact

Front 14

How does cholesterol in animal cell membranes affect the fluidity of the bilayer?

Back 14

More rigid , less fluid

Front 15

The smooth ER is especially abundant in cells that synthesize extensive amounts of

Back 15

Lipids

Front 16

Which of the following organelles is found in plant cells but not in animal cells?

Back 16

a. Ribosomes

b. ER

c. Mitochondria

d. Peroxisomes

E. None of the above

Front 17

True or False: Because they have chloroplasts for energy production, plant cells lack mitochondria.

Back 17

False

Front 18

Ribosomes are found

Back 18

In the cytoplasm + attached to the ER

Front 19

The golgi apparatus is involved in

Back 19

(like fedex) it modifies and packages proteins that were synthesized by the ER.

Front 20

Exocytosis is a process by which cells

Back 20

Release substances directly into the extracellular fluid through the fusion of vesicles with the plasma membrane

Front 21

Red blood cells have a characteristic concave shape because of

Back 21

Spectrin

Front 22

Substances transported by facilitated diffusion

Back 22

Move passively through specific channels from an area of greater concentration to one of lower concentration

Front 23

What is the difference between passive transport and active transport?

Back 23

Passive transport requires NO energy(ATP), movement is from a high to a low concentration (down the concentration gradient). and Active transport requires energy, low to high concentration

Front 24

What is a liposome?

Back 24

a minute spherical sac of phospholipid molecules enclosing a water droplet, especially as formed artificially to carry drugs or other substances into the tissues.tiny vesicle made out f the same material as a cell membrane.

Front 25

True or False: The flow of protons (H+) out of the cell (which is less acidic than the extracellular space) occurs via active transport by the proton pump.

Back 25

True

Front 26

True or False: Only channels, no transporters, can mediate passive transport.

Back 26

False, transporters are allowed to help

Front 27

Which are the three possible sources of energy for pumps that act as an active transporters?

Back 27

Atp, light, coupled transporter

Front 28

What is the difference between flippase, floppase and scramblese.

Back 28

Flippase: only moves phospholipids from the extracellular leaflet to the cytosolic leaflet, maintaining asymmetry of the membrane.

Floppase: use ATP to transport substrates such as phosphatidylcholine (PC), sphingolipid (SL) and cholesterol against concentration gradients in the opposite direction

Scramblese: randomly moves phospholipid molecules between two leaflets of the bilayer (in both directions), thus promotes symmetry on both halves of the bilayer

Front 29

Give an example of antiport transport.

Back 29

Ions go in opposite directions. Cotransported ions go out of transporter and transport molecules go in.

Front 30

True or False: The plasma membrane is highly impermeable to all charged molecules.

Back 30

True

Front 31

True or False: The membrane potential of an axon temporarily becomes more negative when an action potential excites it.

Back 31

False, because The peak of an action potential corresponds
to a transient shift of the membrane potential from a negative to a positive value. The influx of Na+ causes the membrane potential first to move toward zero and then to reverse, rendering the cell positively charged on its inside. Eventually, the resting potential is restored by an efflux of K+ through voltage-gated K+ channels and K+ leak channels.

Front 32

Define depolarization.

Back 32

As the sodium rushes back into the cell the positive sodium ions raise the charge inside of the cell from negative to positive. Once the interior of the cell becomes positively charged, depolarization of the cell is complete.

Front 33

After stimulation, depolarization in a neuron occurs and causes

Back 33

Influx of Na+ through Na+ voltage gated channels

Front 34

True or False: Repolarization of the membrane during the action potential occurs when K+ voltage gated channels opens and allow the efflux of K+ out of the cell.

Back 34

True

Front 35

What determine the membrane potential?

Back 35

(membrane pot. is the concentration inside the cell) The membrane pot. is a fluctuation between the positive and negative between the cell. When the cell is negative its at resting potential.

Front 36

H+ pumps in cells are important for

Back 36

pH regulation

Front 37

What is the role of the K+ leak channels in maintaining the membrane potential?

Back 37

Cell membranes are considerably more permeable to K+ than to Na+ because they have many more K+ leak channels than Na+ leak channels.

Front 38

Predict which one of the following organisms will have the highest percentage of unsaturated phospholipids in its membranes. Explain your answer.

Back 38

Antarctic Fish