Chapter 7: Key points

Question 1

Concept Mastery Alert: Receptor Sites and Diabetes

Answer 1

Protein receptors are embedded in the cell membrane to carry out a specific function. Specific chemicals react with the protein receptors outside the cell to stimulate a reaction within the cell. For example, the receptor site for insulin reacts with the hormone insulin to cause activation of specific enzymes within the cell to change the cell membrane’s permeability and allow more glucose into the cell, in addition to other metabolic cellular changes.

Question 2

The cell is the:

Answer 2

The cell is the basic structure of all living organisms.

Question 3

The cell nucleus is the:

Answer 3

The cell nucleus is the location of genetic material held in DNA molecules.

Question 4

The cell membrane:

Answer 4

The cell membrane features specific receptor sites that allow interaction with various chemicals, histocompatibility proteins that allow for self-identification, and channels or pores that allow for the passage of substances into and out of the cell.

Question 5

The cytoplasm of the cell contains:

Answer 5

The cytoplasm of the cell contains various organelles that are important for cellular function.

Question 6

Structures and functions summary:

Answer 6

The mitochondria produce energy for the cell; the endoplasmic reticulum contains ribosomes that produce proteins; the Golgi apparatus packages proteins; and lysosomes contain protein-dissolving enzymes that are important for digestion and the recycling of organisms in nature.

Question 7

Cells and the cell cycle:

Answer 7

Many cells progress through a cell cycle, which allows them to reproduce.

Question 8

The cell cycle includes:

Answer 8

The cell cycle includes a resting phase (G0) a gap phase (G1), when the components needed for cell division are collected by the cell; a synthesizing phase (S), when DNA and other components are produced; a final gap phase (G2), when the last substances needed for division are collected and produced; and an M phase, when actual cell division occurs, producing two identical daughter cells.

Question 9

Summary: the cell is composed of

Answer 9

The cell is composed of a nucleus, which contains genetic material and controls the production of proteins by the cell; a cell membrane, which separates the inside of the cell from the outside environment; and a cytoplasm, which contains various organelles important to cell function.

Question 10

Summary: the cell membrane functions as?

Answer 10

The cell membrane functions as a fluid barrier made of lipids and proteins. The arrangement of the lipoprotein membrane controls what enters and leaves the cell.

Question 11

Summary: proteins on the cell membrane surface

Answer 11

Proteins on the cell membrane surface can act either as receptor sites for specific substances or as histocompatibility markers that identify the cell as a self-cell (i.e., a cell belonging to that individual).

Question 12

Summary: what do channels or pores in the cell membrane allow for?

Answer 12

Channels or pores in the cell membrane allow for easier movement of specific substances needed by the cell for normal functioning.

Question 13

Summary: mitochondria

Answer 13

Mitochondria are rod-shaped organelles that produce energy in the form of ATP for use by cells.

Question 14

Summary: ribosomes

Answer 14

Ribosomes are sites of protein production within the cell cytoplasm. The specific proteins produced by a cell are determined by the genetic material within the cell nucleus.

Question 15

Summary: the Golgi apparatus

Answer 15

The Golgi apparatus packages particular substances for removal from the cell (e.g., neurotransmitters, hormones).

Question 16

Summary: Lysosomes

Answer 16

Lysosomes are packets of digestive enzymes located in the cell cytoplasm. These enzymes are responsible for destroying injured or nonfunctioning parts of the cell and for promoting cellular disintegration when the cell dies.

Question 17

Summary: explain the process of Endocytosis

Answer 17

Endocytosis is the process of moving substances into a cell by extending the cell membrane around the substance and engulfing it. Pinocytosis refers to the engulfing of necessary materials, and phagocytosis refers to the engulfing and destroying of bacteria or other proteins by white blood cells.

Question 18

Summary: explain the process of Exocytosis

Answer 18

Exocytosis is the process of removing substances from a cell by moving them toward the cell membrane and then changing the cell membrane to allow passage of the substance out of the cell.

Question 19

Summary: how do cells maintain homeostasis?

Answer 19

Cells maintain homeostasis by regulating the movement of solutes and water into and out of the cell.

Question 20

Summary: explain the process of Diffusion

Answer 20

Diffusion, which does not require energy, is the movement of solutes from a region of high concentration to a region of lower concentration across a concentration gradient.

Question 21

Summary: explain the process of Osmosis

Answer 21

Osmosis, which like diffusion does not require energy, is the movement of water from an area low in solutes to an area high in solutes. Osmosis exerts a pressure against the cell membrane that is called osmotic pressure.

Question 22

Summary: explain the process of Active Transport

Answer 22

Active transport, an energy-requiring process, is the movement of particular substances against a concentration gradient. Active transport is important in maintaining cell homeostasis.

Question 23

Summary: cell replication and the cell cycle

Answer 23

Cells replicate at differing rates, depending on the genetic programming of the cell. Many cells go through a life cycle consisting of the following phases: G0, the resting phase; G1, which involves the production of proteins for DNA synthesis; S, which involves the synthesis of DNA; G2, which involves manufacture of the materials needed for mitotic spindle production; and M, the mitotic phase, in which the cell splits to form two identical daughter cells.