Chapter 5 Flashcards
(45 cards)
Allele
A variant form of a gene at a specific gene locus. Example: The gene for fur length in cats has two alleles: L (dominant, short hair) and l (recessive, long hair).
Bottleneck
A sharp reduction in a population’s size due to events like natural disasters or hunting, reducing genetic diversity. Example: Cheetahs went through a bottleneck, leading to low genetic variation.
Differentiation
The process by which distinct populations or species develop differences due to genetic, environmental, or selective factors.
Dimorphic, Dimorphism
The occurrence of two distinct forms within a species. Example: Male and female peacocks show sexual dimorphism, with males having bright plumage and females being brown.
Diploid
A cell or organism with two sets of chromosomes (2n), one from each parent. Example: Humans are diploid (46 chromosomes, 23 pairs).
Genetic differentiation among populations
The genetic variation between populations due to factors like mutation, selection, or genetic drift. Example: Different finch populations in the Galápagos evolving distinct beak shapes.
Gene locus
The specific location of a gene on a chromosome.
Haploid
A cell with one set of chromosomes (n), such as gametes (sperm and eggs). Example: Human gametes have 23 chromosomes.
Hexaploid
An organism with six sets of chromosomes (6n). Example: Wheat is hexaploid.
Inbreeding depression
Reduced fitness in a population due to breeding between closely related individuals, increasing harmful recessive traits. Example: Purebred dogs sometimes suffer from genetic disorders due to inbreeding.
Incomplete dominance
A pattern of inheritance where a heterozygote shows a blended phenotype. Example: A red (RR) and white (rr) flower producing pink (Rr) offspring.
Karyotype
A visual display of an individual’s chromosomes, used to detect genetic abnormalities.
Monomorphic
A trait that exists in only one form in a population. Example: All cheetahs have spotted fur; there is no variation in this trait.
Multilocus
Involving multiple gene loci. Example: Height in humans is influenced by multiple genes, making it a multilocus trait.
Negative frequency-dependent selection
A form of natural selection where rare traits are favored. Example: In some species of fish, left-mouthed and right-mouthed individuals alternate in frequency due to predator adaptation.
Pentaploid
An organism with five sets of chromosomes (5n).
Ploidy level
The number of chromosome sets in an organism. Example: Humans are diploid (2n), while strawberries can be octoploid (8n).
Polygenic
A trait controlled by multiple genes. Example: Skin color and height in humans are polygenic traits
Polymorphic
A trait with multiple forms in a population. Example: Butterfly wings that show different colors or patterns.
Tetraploid
An organism with four sets of chromosomes (4n). Example: Some plants, like coffee, are tetraploid.
Triploid
An organism with three sets of chromosomes (3n), often sterile. Example: Seedless watermelons are triploid.
Adaptation
A trait that improves an organism’s survival and reproduction in its environment.
Alleles
Different versions of a gene that contribute to phenotypic variation.
Chromosomes
Structures made of DNA that contain genes.
