chapter 7

Question 1

Why do cells need to move substances through their membrane?

Answer 1

To bring in nutrients, oxygen, and water and to release wastes, carbon dioxide, and excess water

Question 2

What is a phospholipid?

Answer 2

Lipids that are the most abundant molecule type in the plasma membrane, consist of two fatty acid tails attached to a glycerol head that is bonded to a phosphate group.

Question 3

What is a plasma membrane?

Answer 3

The membrane that surrounds the cell

Question 4

What chemical properties of the phospholipid are important to a cell membrane (plasma membrane)?

Answer 4

They are amphipathic. This means that they have both hydrophilic and hydrophobic parts.

Question 5

In what way is the phospholipid bilayer “fluid”?

Answer 5

It has the consistency of salad oil

Question 6

What effect does cholesterol have on a membrane?

Answer 6

At warm temperatures, cholesterol restrains movement of phospholipids. At cool temperatures, it maintains fluidity by preventing tight packing

Question 7

What is osmosis?

Answer 7

the diffusion of water across a selectively permeable membrane

Question 8

How is osmosis different from diffusion?

Answer 8

Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentration is equal on both sides.

Question 9

How is osmosis similar to diffusion

Answer 9

Both are passive transport

Question 10

Diffusion

Answer 10

The tendency for molecules to spread out evenly into the available space; Substances diffuse down their concentration gradient, the region along which the density of a chemical substance increases or decreases

Question 11

Osmosis

Answer 11

the diffusion of water across a selectively permeable membrane; Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentration is equal on both sides

Question 12

concentration gradient

Answer 12

the region along which the density of a chemical substance increases or decreases

Question 13

Equilibrium

Answer 13

have approximately equal amounts of solute on either side of a membrane

Question 14

How an Isotonic solution affects an animal and plant cell

Answer 14

animal cell size stays the same (ideal condition for animal cell), plant cell becomes flaccid causing the plant to wilt;

Question 15

How a hypotonic solution affects an animal and plant cell

Answer 15

animal cell increases in size and may lyse, plant cell becomes turgid and makes the plant rigid by putting pressure against plant cell wall (ideal condition for plant cell)

Question 16

How a hypertonic solution affects an animal and plant cell

Answer 16

would pull water out of both plant and animal cells causing animal cells to shrivel and plant cells to plasmolyze, both types of cells would die

Question 17

facilitated diffusion

Answer 17

transport proteins speed the passive movement across the plasma membrane by diffusion

Question 18

active transport

Answer 18

transport that moves solutes against their concentration gradient; uses carrier transport proteins and requires energy, usually in the form of ATP

Question 19

passive transport

Answer 19

occurs through diffusion, doesn’t require energy to move molecules down the concentration gradient; includes simple diffusion, osmosis, and facilitated diffusion

Question 20

Function of membrane protein: Transport

Answer 20

move substances around the cell or into/out of the cell

Question 21

Function of membrane protein: enzymatic activity

Answer 21

speed up reactions

Question 22

Function of membrane protein: signal transduction

Answer 22

allow for cell to cell communication

Question 23

Function of membrane protein: cell-cell recognition

Answer 23

allow neighboring or immune cells to recognize that the cell is part of the body

Question 24

Function of membrane protein: intercellular joining

Answer 24

allow attachment between neighboring cells

Question 25

Function of membrane protein: attachment to cytoskeleton and ECM

Answer 25

cross membrane proteins that hold ECM in place

Question 26

How do channel proteins aid in facilitated diffusion

Answer 26

Channel proteins provide corridors that allow a specific molecule or ion to cross the membrane

Question 27

How do carrier proteins aid in facilitated diffusion

Answer 27

Carrier proteins undergo a subtle change in shape that translocates the solute-binding site across the membrane

Question 28

Why is active transport needed?

Answer 28

Because the ions are being moved against their concentration gradient from areas of low concentration to areas of high concentration

Question 29

Mechanisms that permit bulk transport across the cell membrane.

Answer 29

Exocytosis and endocytosis

Question 30

Exocytosis

Answer 30

transport vesicles migrate to the membrane, fuse with it, and release their contents; Many secretory cells use exocytosis to export their products

Question 31

endocytosis

Answer 31

the cell takes in macromolecules by forming vesicles from the plasma membrane (reversal of exocytosis); Types of endocytosis: Phagocytosis and Pinocytosis

Question 32

Phagocytosis

Answer 32

(“cellular eating”) cell engulfs a particle in a vacuole,

Question 33

Pinocytosis

Answer 33

(“cellular drinking”) cell takes in extracellular fluid