Chapter 3 Cell Structure and Function

Question 1

4 basic concepts of the cell theory:

Answer 1

1. Cells are the building blocks of all plants and animals
2. Cells are the smallest functioning units of life
3. Cells are produced through the division of pre-exisitng cells
4. Each cell maintains homeostasis

Question 2

Cytology

Answer 2

The study of the structure and function of cells

Question 3

Our model body cell is surrounded by a watery medium known as:

Answer 3

extracellular fluid

Question 4

Cytoplasm can be subdivided into:

Answer 4

a liquid - the cytosol, and intracellular structures - organelles

Question 5

What is the cell membrane?

Answer 5

the outer boundary of the cell; aka plasma membrane

Question 6

What are the general functions of the cell membrane?

Answer 6

1. physical isolation: separates the inside of the cell from the extracellular fluid
2. regulation of exchange with the environment: control the entry of ions and nutrients, the elimination of wastes, and the release of secretions
3. sensitivity: it is the first part of the cell affected by changes in the extracellular fluid
4. structural support

Question 7

The cell membrane ranges from ____ to ____ nm in thickness.

Answer 7

6 to 10

Question 8

Phospholipids are a major component of cell membranes. In a phospholipid, a phosphate group serves as a link between:

Answer 8

a diglyceride and a nonlipid “head”

Question 9

How do the phospholipids in a cell membrane lie?

Answer 9

with the hydrophilic (soluble in water) heads on the outside, and the hydrophobic (insoluble in water) tails on the inside

Question 10

Passive processes move ions or molecules across the cell membrane:

Answer 10

without any energy expenditure by the cell

Question 11

Active processes require that the cell:

Answer 11

expend energy, usually in the form of adenosine triphosphate (ATP)

Question 12

An ion or molecule can independently diffuse across a cell membrane in one of two ways:

Answer 12

1. by moving across the lipid portion of the membrane

2. by passing through a channel protein in the membrane

Question 13

Osmosis

Answer 13

The diffusion of water across a membrane

Question 14

Three important characteristics of osmosis:

Answer 14

1. Osmosis is the diffusion of water across a membrane
2. Osmosis occurs across a selectively permeable membrane that is freely permeable to water but is not freely permeable to solutes
3. In osmosis, water flows across a membrane toward the solution that has the higher concentration of solutes, because that is where the water concentration is lower.

Question 15

Isotonic solution

Answer 15

one that does not cause a net movement of water into or out of the cell

Question 16

Hypotonic solution

Answer 16

water will flow into the cell

Question 17

Hypertonic solution

Answer 17

water will flow out of the cell

Question 18

When placed in a hypertonic solution, a red blood cell will:

Answer 18

lose water by osmosis; called crenation

Question 19

Carrier-mediated transport

Answer 19

membrane proteins bind specific ions or organic substrates and carry them across the cell membrane

Question 20

Active transport

Answer 20

the high-emery bond in ATP provides the energy needed to move ions or molecules across the membrane. The cell can import or export specific materials regardless of their intracellular or extracellular concentrations

Question 21

Sodium ion concentrations are:

Answer 21

high in the extracellular fluid but low in the cytoplasm

Question 22

Potassium ion concentrations are:

Answer 22

low in the extracellular fluid but high in the cytoplasm

Question 23

The sodium-potassium exchange pump

Answer 23

maintains sodium and potassium concentration gradients across the cell membrane by ejecting sodium ions and recapturing lost potassium ions. For each ATP molecule consumed, three sodium ions are ejected and two potassium ions are reclaimed by the cell

Question 24

Vesicular transport

Answer 24

materials move into or out of the cell in vesicles, which are small membranous sacs that form at, or fuse with, the cell membrane

Question 25

The two major categories of vesicular transport are:

Answer 25

endocytosis and exocytosis

Question 26

Cytoplasm

Answer 26

a general term for the material inside the cell, from the cell membrane to the nucleus

Question 27

The cytoplasm contains ____ and ____

Answer 27

cystol and organelles

Question 28

Microvilli

Answer 28

small, finger-shaped projections of the cell membrane on the exposed surfaces of many cells. They absorb materials from the extracellular fluid

Question 29

Centrioles

Answer 29

a cylindrical structure composed of short microtubules. They produce the spindle fibers that move DNA strands during cell division

Question 30

Cilia

Answer 30

relatively long, slender extensions of the cell membrane. Their coordinated actions move fluids or secretions across the cell surface

Question 31

Flagella

Answer 31

resemble cilia but are much longer. They move a cell through the surrounding fluid

Question 32

Ribosomes

Answer 32

organelles that manufacture proteins, using information provided by the DNA of the nucleus

Question 33

Golgi apparatus

Answer 33

consist of a set of five or six flattened, membranous discs.

Question 34

Lysosomes

Answer 34

vesicles filled with digestive enzymes; perform cleanup and recycling functions within the cell

Question 35

Mitochondria

Answer 35

small organelles that provide energy for the cell