Chapter 4 - Genes and their evolution

Question 1

Abnormal Hemoglobin

Answer 1

Hemoglobin altered so that it is less efficient in binding to and carrying oxygen

Question 2

Admixture

Answer 2

The exchange of genetic material between two or more populations

Question 3

Anthropogenic

Answer 3

Refers to any effect caused by humans

Question 4

Balanced polymorphism

Answer 4

Situation in which selection maintains two or more phenotypes for a specific gene in a population

Question 5

Capillaries

Answer 5

Small blood vessels between the terminal ends of arteries and the veins

Question 6

deme

Answer 6

A local population of organisms that have similar genes, interbreed, and produce offspring

Question 7

demic diffusion

Answer 7

A population’s movement into an area previously uninhabited by that group

Question 8

directional selection

Answer 8

Selection for one allele over the other alleles, causing the allele frequencies to shift in one direction

Question 9

disruptive selection

Answer 9

Selection for both extremes of the phenotypic distribution; may eventually lead to a speciation event

Question 10

endogamous

Answer 10

Refers to a population in which individuals breed only with other members of the population

Question 11

equilibrium

Answer 11

A condition in which the system is stable, balanced, and unchanging

Question 12

exogamouse

Answer 12

Refers to a population in which individuals breed only with nonmembers of their population

Question 13

fitness

Answer 13

Average number of offspring produced by parents with a particular genotype compared to the number of offspring produced by parents with another genotype

Question 14

founder effect

Answer 14

The accumulation of random genetic changes in a small population that has become isolated from the parent population due to the genetic input of only a few colonizers

Question 15

frameshift mutation

Answer 15

The change in a gene due to the insertion or deletion of one or more nitrogen bases, which causes the subsequent triplets to be rearranged and the codons to be read incorrectly during translation

Question 16

G6PD

Answer 16

An enzyme that aids in the proper functioning of red blood cells; its deficiency, a genetic condition, leads to hemolytic anemia

Question 17

gene pool

Answer 17

All the genetic information in the breeding population

Question 18

Hardy-Weinberg law of equilibrium

Answer 18

A mathematical model in population genetics that reflects the relationship between frequencies of alleles and of genotypes; it can be used to determine whether a population is undergoing evolutionary changes

Question 19

Hemoglobinopathies

Answer 19

A group of related genetic blood diseases characterized by abnormal hemoglobin

Question 20

Hemolytic anemias

Answer 20

Conditions of insufficient iron in the blood due to the destruction of red blood cells resulting from genetic blood diseases, toxins, or infectious pathogens

Question 21

Huntington’s chorea

Answer 21

A rare genetic disease in which the central nervous system degenerates and the individual loses control over voluntary movements, with the symptoms often appearing between ages 30 and 50

Question 22

Klinefelter’s syndrome

Answer 22

A chromosomal trisomy in which males have an extra X chromosome, resulting in an XXY condition; affected individuals typically have reduced fertility

Question 23

macroevolution

Answer 23

Large-scale evolution, such as a speciation event, that occurs after hundreds or thousands of generations

Question 24

melanic

Answer 24

Refers to an individual with high concentrations of melanin

Question 25

microevolution

Answer 25

Small-scale evolution, such as changes in allele frequency, that occurs from one generation to the next

Question 26

mutagens

Answer 26

Substances, such as toxins, chemicals, or radiation, that may induce genetic mutations

Question 27

nonmelanic

Answer 27

Refers to an individual with low concentrations of melanin

Question 28

nonsynonymous point mutation

Answer 28

A point mutation that creates a triplet coded to produce a different amino acid from that of the original triplet

Question 29

point mutations

Answer 29

Replacements of a single nitrogen base with another base, which may or may not affect the amino acid for which the triplet codes

Question 30

positive selection

Answer 30

Process in which advantageous genetic variants quickly increase in frequency in a population

Question 31

reproductive isolation

Answer 31

Any circumstance that prevents two populations from interbreeding and exchanging genetic material, such as when two populations are separated by a large body of water or a major mountain range

Question 32

sickle-cell anemia

Answer 32

A genetic blood disease in which the red blood cells become deformed and sickle-shaped, decreasing their ability to carry oxygen to tissues

Question 33

spontaneous mutations

Answer 33

Random changes in DNA that occur during cell division

Question 34

stabilizing selection

Answer 34

Selection against the extremes of the phenotypic distribution, decreasing the genetic diversity for this trait in the population

Question 35

synonymous point mutation

Answer 35

A neutral point mutation in which the substituted nitrogen base creates a triplet coded to produce the same amino acid as that of the original triplet

Question 36

thalassemia

Answer 36

A genetic blood disease in which the hemoglobin is improperly synthesized, causing the red blood cells to have a much shorter life span

Question 37

transposable elements

Answer 37

Mobile pieces of DNA that can copy themselves into entirely new areas of the chromosomes