Chapter 4 - Genes and their evolution Flashcards
Abnormal Hemoglobin
Hemoglobin altered so that it is less efficient in binding to and carrying oxygen
Admixture
The exchange of genetic material between two or more populations
Anthropogenic
Refers to any effect caused by humans
Balanced polymorphism
Situation in which selection maintains two or more phenotypes for a specific gene in a population
Capillaries
Small blood vessels between the terminal ends of arteries and the veins
deme
A local population of organisms that have similar genes, interbreed, and produce offspring
demic diffusion
A population’s movement into an area previously uninhabited by that group
directional selection
Selection for one allele over the other alleles, causing the allele frequencies to shift in one direction
disruptive selection
Selection for both extremes of the phenotypic distribution; may eventually lead to a speciation event
endogamous
Refers to a population in which individuals breed only with other members of the population
equilibrium
A condition in which the system is stable, balanced, and unchanging
exogamouse
Refers to a population in which individuals breed only with nonmembers of their population
fitness
Average number of offspring produced by parents with a particular genotype compared to the number of offspring produced by parents with another genotype
founder effect
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
frameshift mutation
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
G6PD
An enzyme that aids in the proper functioning of red blood cells; its deficiency, a genetic condition, leads to hemolytic anemia
gene pool
All the genetic information in the breeding population
Hardy-Weinberg law of equilibrium
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
Hemoglobinopathies
A group of related genetic blood diseases characterized by abnormal hemoglobin
Hemolytic anemias
Conditions of insufficient iron in the blood due to the destruction of red blood cells resulting from genetic blood diseases, toxins, or infectious pathogens
Huntington’s chorea
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
Klinefelter’s syndrome
A chromosomal trisomy in which males have an extra X chromosome, resulting in an XXY condition; affected individuals typically have reduced fertility
macroevolution
Large-scale evolution, such as a speciation event, that occurs after hundreds or thousands of generations
melanic
Refers to an individual with high concentrations of melanin
microevolution
Small-scale evolution, such as changes in allele frequency, that occurs from one generation to the next
mutagens
Substances, such as toxins, chemicals, or radiation, that may induce genetic mutations
nonmelanic
Refers to an individual with low concentrations of melanin
nonsynonymous point mutation
A point mutation that creates a triplet coded to produce a different amino acid from that of the original triplet
point mutations
Replacements of a single nitrogen base with another base, which may or may not affect the amino acid for which the triplet codes
positive selection
Process in which advantageous genetic variants quickly increase in frequency in a population
reproductive isolation
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
sickle-cell anemia
A genetic blood disease in which the red blood cells become deformed and sickle-shaped, decreasing their ability to carry oxygen to tissues
spontaneous mutations
Random changes in DNA that occur during cell division
stabilizing selection
Selection against the extremes of the phenotypic distribution, decreasing the genetic diversity for this trait in the population
synonymous point mutation
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
thalassemia
A genetic blood disease in which the hemoglobin is improperly synthesized, causing the red blood cells to have a much shorter life span
transposable elements
Mobile pieces of DNA that can copy themselves into entirely new areas of the chromosomes
