Chapter 7

Question 1

What are lipid rafts?

Answer 1

specific lipids in groups of proteins that are in specialized patches within membrane

Question 2

compare the speed of protein to lipid movement on the membrane

Answer 2

proteins move slowly because they are larger, some are even immobile by attachment to cytoskeleton or ECM

Question 3

Describe the membrane of a fish that lives at extreme cold temperatures

Answer 3

high portion of unsaturated carbon tails to remain fluid at low temperatures

Question 4

Describe how peripheral proteins are attached to the lipid bilayer

Answer 4

NOT embedded, loosely bound to surface

Question 5

Membrane carbohydrates are important because

Answer 5

they function as markers that distinguish one cell from the other

Question 6

Describe the synthesis of membrane components in the ER

Answer 6

secretory proteins, membrane proteins, lipids synthesized in ER.

Carbohydrates are added to transmembrane proteins to make glycoproteins.

Materials then transported to golgi via vesicles

Question 7

Describe the synthesis of transmembrane components in the golgi

Answer 7

glyoproteins have more carb modification and lipids become glycolipids

Question 8

After transmembrane components have left the golgi, they are transported to the plasma membrane via _____

Answer 8

vesicles

Question 9

What occurs when the vesicles fuse with the plasma membrane after leaving the golgi?

Answer 9

As vesicles fuse with the plasma membrane, the outside face of the vesicle becomes continuous with the inside (cytoplasmic) face of the plasma membrane. This releases the secretory proteins from the cell, a process called exocytosis

positions the carbohydrates of membrane glycoproteins and glycolipids on the outside (extracellular) face of the plasma membrane

Question 10

A small, non polar molecule has ___ permeability across the membrane

Answer 10

high

Question 11

What types of molecules would require transport proteins?

Answer 11

some ions and polar molecules

Question 12

How do channel proteins function?

Answer 12

a hydrophilic channel that certain molecules or ions use as a tunnel through the membrane

Question 13

What are carrier proteins

Answer 13

hold on to their passengers and change shape in a way
that shuttles them across the membrane

Question 14

What occurs when a cell with a cell wall is immersed in a hypotonic solution?

Answer 14

it helps maintain the water balance, as the cell wall will expand before it exerts turgor pressure back onto the cell, keeping it firm

Question 15

What will occur if a plant cell is in an isotonic solution?

Answer 15

there is no net tendency for water to enter and the cells become flaccid

Question 16

If kidneys didn’t have high numbers of aquaporins, what would happen?

Answer 16

the massive levels of diffusion of water would not be regulated, you’d be peeing all the time

Question 17

The two proteins primarily responsible for facilitated diffusion are

Answer 17

channel and carrier

Question 18

Compare ion proteins to carrier proteins

Answer 18

ion proteins: open and close due to an electrical or chemical stimulus

carrier: undergo a subtle change in shape

Question 19

Speculate about how a cell performing cellular respiration
might rid itself of the resulting CO2

Answer 19

CO2 is a nonpolar molecule that can diffuse through the plasma membrane.
As long as it diffuses away so that the concentration remains low outside the
cell, it will continue to exit the cell in this way.

Question 20

If a Paramecium swims from a hypotonic to an
isotonic environment, will its contractile vacuole become
more active or less? Why?

Answer 20

Paramecium’s contractile
vacuole will become less active. The vacuole pumps out excess water that accumulates in the cell; this accumulation occurs only in a hypotonic environment.

Question 21

What is voltage? Describe the charges of the cytoplasmic side of the membrane relative to ECM

Answer 21

voltage: electrical POTENTIAL energy

cytoplasmic side is negative because of unequal districution of anions and cations on both sides

Question 22

Why does membrane potential favor the passive transport of cations into the cell and anions out of cell?

Answer 22

because inside of cell is negative compared to outside

Question 23

Two forces drive the diffusion of ions across a membrane. What are they?

Answer 23

a chemical force (ion’s concentration gradient)

And electrical force (membrane potential)

Question 24

Why is the sodium potassium pump a good example of an electrogenic pump?

Answer 24

Notice that the pump does not translocate Na + and K + one
for one, but pumps three sodium ions out of the cell for every
two potassium ions it pumps into the cell. With each “crank”
of the pump, there is a net transfer of one positive charge
from the cytoplasm to the extracellular fluid, a process that
stores energy as voltage

Question 25

Na+/K + pumps help nerve cells establish a voltage across their plasma membranes. Do these pumps use ATP or produce ATP? Explain.

Answer 25

These pumps use ATP. To establish a voltage, ions have to be pumped against
their gradients, which requires energy

Question 26

Explain why the Na+/K + pump would not be considered a cotransporter.

Answer 26

Each ion is being transported against
its electrochemical gradient. If either ion were transported down its electrochem-
ical gradient, this would be considered cotransport.

Question 27

Bulk transport across the plasma membrane occurs by which two processes?

Answer 27

exocytosis and endocytosis

Question 28

Describe the process of exocytosis

Answer 28

cell secretes certain molecules by fusion of vesicles with plasma membrane.
The vesicles came from the golgi and moved along a microtubule to reach plasma membrane.

Question 29

Describe process of endocytosis

Answer 29

the cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane.

1. small area of plasma membrane sinks inward to form a pocket
2. it pinches in and forms a vesicle containing material from ECM

Question 30

Phagocytosis involves forming a vesicle around a ____ to be __ in the cell

Answer 30

food or other particle

digested

Question 31

Pinocytosis involves ___ in a vesicle. The vesicles are often lined with ___

Answer 31

droplets of extracellular fluid

often lined with fuzzy layer of coat protein, the vesicles are called coated pits

Question 32

As a cell grows, its plasma membrane expands. Does this
involve endocytosis or exocytosis? Explain

Answer 32

Exocytosis. When a transport vesicle fuses with the plasma membrane, the
vesicle membrane becomes part of the plasma membrane

Question 33

In Concept 6.7, you learned that
animal cells make an extracellular matrix (ECM). Describe
the cellular pathway of synthesis and deposition of an ECM
glycoprotein.

Answer 33

The glycoprotein is synthesized in the ER lumen,
moves through the Golgi apparatus, and then travels in a vesicle to the plasma membrane, where it
undergoes exocytosis and becomes part of the ECM

Question 34

In what way do the membranes of a eukaryotic cell vary?
(A) Phospholipids are found only in certain membranes.
(B) Certain proteins are unique to each membrane.
(C) Only certain membranes of the cell are selectively permeable.
(D) Only certain membranes are constructed from amphipathic
molecules.

Answer 34

Q1 B

Question 35

According to the fluid mosaic model of membrane structure,
proteins of the membrane are mostly
(A) spread in a continuous layer over the inner and outer
surfaces of the membrane.
(B) confined to the hydrophobic interior of the membrane.
(C) embedded in a lipid bilayer.
(D) randomly oriented in the membrane, with no fixed inside-
outside polarity.

Answer 35

(C) embedded in a lipid bilayer.

Question 36

Which of the following processes includes all the others?
(A) osmosis
(B) diffusion of a solute across a membrane
(C) passive transport
(D) transport of an ion down its electrochemical gradient

Answer 36

Q5 B