Chapter 45 Definitions SLO 2.2

Question 1

Acquired immune deficiency syndrome (AIDS)

Answer 1

Infection caused by the human immunodeficiency virus (HIV), which weakens the host’s immune system, giving rise to opportunistic infections. (p. 732)

Question 2

Antibodies

Answer 2

Immunoglobulin molecules that have an antigen-specific amino acid sequence and are produced by the humoral immune system (antibodies produced from B lymphocytes) in response to exposure to a specific antigen, the purpose of which is to attack and destroy molecules of this antigen. (p. 733)

Question 3

Antigen

Answer 3

A substance, usually a protein, that is foreign to a host and causes the formation of an antibody and reacts specifically with that antibody. Examples of antigens include bacterial exotoxins, viruses, and allergens. An allergen (e.g., dust, pollen, mould) is a specific type of antigen that causes allergic reactions (see Chapter 37). (p. 733)

Question 4

Antiretroviral drugs

Answer 4

A more specific term for antiviral drugs that work against retroviruses such as HIV. (p. 734)

Question 5

Antiviral drugs

Answer 5

Drugs that destroy viruses, either directly or indirectly, by suppressing their replication. (p. 734)

Question 6

Cell-mediated immunity (CMI)

Answer 6

One of two major parts
of the immune system. CMI consists of nonspecific immune responses mediated primarily by T lymphocytes (T cells) and other immune system cells (e.g., monocytes, macrophages, neutrophils) but not antibody-producing cells (B lymphocytes). (p. 733)

Question 7

Deoxyribonucleic acid (DNA)

Answer 7

A nucleic acid composed
of nucleotide units that contain molecules of the sugar deoxyribose, phosphate groups, and purine and pyrimidine bases. DNA molecules transmit genetic information and are found primarily in the nuclei of cells. (Compare with ribonucleic acid [RNA]). (p. 732)

Question 8

Fusion

Answer 8

The process by which viruses attach themselves to, or fuse with, the cell membranes of host cells, in preparation for infecting the cell for purposes of viral replication.
(p. 732)

Question 9

Genome

Answer 9

The complete set of genetic material of any organism. The genome may consist of multiple chromosomes (groups of DNA or RNA molecules) in higher organisms; a single chromosome, as in bacteria; or one or two DNA or RNA molecules, as in viruses. (p. 732)

Question 10

Herpesviruses

Answer 10

Several different types of viruses belonging to the family Herpesviridae that cause various forms of herpes infection. (p. 733)

Question 11

Host

Answer 11

Any organism that is infected with a microorganism, such as bacteria or viruses. (p. 732)

Question 12

Human immunodeficiency virus (HIV)

Answer 12

The retrovirus that causes AIDS. (p. 732)

Question 13

Humoral immunity

Answer 13

One of two major parts of the immune system. Humoral immunity consists of specific immune responses in the form of antigen-specific antibodies produced from B lymphocytes (B cells). (p. 733)

Question 14

Immunoglobulins

Answer 14

Glycoproteins produced and used by the humoral immune system to attack and kill any substance (antigen) that is foreign to the body. An immunoglobulin with an antigen-specific amino acid sequence is called an antibody and is able to recognize and inactivate molecules of a specific antigen. (Also called immune globulin.) (p. 734)

Question 15

Influenza viruses

Answer 15

Viruses that cause influenza, an acute viral infection of the respiratory tract. There are three types of influenza virus: A, B, and C. Currently, medications are available to treat only types A and B. (p. 734)

Question 16

Nucleic acids

Answer 16

Complex biomolecules, including DNA and RNA, that contain the genetic material of all living organisms, which is passed to future generations during reproduction. (p. 732)

Question 17

Nucleoside

Answer 17

A structural component of nucleic acid molecules (DNA or RNA) that consists of a purine or pyrimidine base attached to a sugar molecule. (p. 734)

Question 18

Nucleotide

Answer 18

A nucleoside that is attached to a phosphate unit, which makes up the side chain “backbone” of a DNA or a RNA molecule. (p. 734)

Question 19

Opportunistic infections

Answer 19

Infections caused by any type of microorganism that occurs in an immunocompromised host but normally would not occur in an immunocompetent host. (p. 734)

Question 20

Protease

Answer 20

An enzyme that breaks down the amino acid structure of protein molecules by chemically cleaving the peptide bonds that link together the individual amino acids. (p. 740)

Question 21

Replication

Answer 21

Any process of duplication or reproduction, such as that involved in the duplication of nucleic acid molecules (DNA or RNA) during the reproduction processes of all living organisms; most commonly describes the entire process of viral reproduction, which occurs only inside the cells of an infected host organism. (p. 732)

Question 22

Retroviruses

Answer 22

Viruses belonging to the family Retroviridae. These viruses contain RNA (as opposed to DNA) as their genome and replicate using the enzyme reverse transcriptase. Currently, the most clinically significant retrovirus is HIV. (p. 733)

Question 23

Reverse transcriptase

Answer 23

An RNA-directed DNA polymerase enzyme. Reverse transcriptase promotes the synthesis of a DNA molecule from an RNA molecule, which is the reverse of the usual process. HIV replicates in this manner. (p. 739)

Question 24

Ribonucleic acid (RNA)

Answer 24

A nucleic acid composed of nucleotide units that contain molecules of the sugar ribose, phosphate groups, and purine and pyrimidine bases. RNA molecules transmit genetic information and are found
in both the nuclei and cytoplasm of cells. (Compare with deoxyribonucleic acid [DNA].) (p. 732)

Question 25

Virion

Answer 25

A mature virus particle. (p. 732)

Question 26

Viruses

Answer 26

The smallest known class of microorganisms; viruses
can replicate only inside host cells. (p. 732)