Chapter 13 Flashcards
(20 cards)
Locus/loci
The specific location on a chromosome where a gene is found (locus is singular, loci is plural).
Heterozygous
Having two different alleles for a particular gene (e.g., Aa).
Homozygous
Having two identical alleles for a particular gene (e.g., AA or aa).
Hybrid
An organism with two different alleles for a specific trait, usually the result of crossbreeding (often used interchangeably with heterozygous).
Genotype
The genetic makeup of an organism, represented by the alleles it possesses (e.g., AA, Aa, or aa).
Allele
Different forms of a gene that determine specific traits (e.g., allele for eye color).
Dominant
An allele that expresses its trait even when only one copy is present (e.g., A for brown eyes).
Recessive
An allele that only expresses its trait when two copies are present (e.g., a for blue eyes).
Phenotype
The observable characteristics or traits of an organism (e.g., brown eyes or blue eyes).
Monohybrid cross
A genetic cross involving one pair of contrasting traits (e.g., crossing two plants for one trait, like flower color).
Dihybrid cross
A genetic cross involving two pairs of contrasting traits (e.g., crossing plants for both flower color and seed shape).
Linkage group
A group of genes that are located close to each other on the same chromosome and tend to be inherited together.
Simple dominance
A pattern of inheritance where one allele completely masks the expression of another (e.g., a dominant allele masking a recessive allele).
Incomplete dominance
A type of inheritance where neither allele is completely dominant, resulting in a blend of both traits (e.g., red and white flowers making pink flowers).
Codominance
A type of inheritance where both alleles are fully expressed in the organism (e.g., blood type AB, where both A and B alleles are expressed).
Epistasis
A form of gene interaction where one gene can mask the expression of another gene (e.g., one gene determining whether pigment will be produced in fur color).
Pleiotropy
A situation where one gene influences multiple, seemingly unrelated traits (e.g., a gene for coat color affecting an animal’s size).
Multiple allele system
A system where more than two alleles exist for a gene, but an individual can only carry two (e.g., blood types A, B, and O).
Polygenic inheritance
A type of inheritance where multiple genes contribute to a single trait (e.g., height or skin color).
Epigenetics
The study of changes in gene expression or traits that do not involve changes in the underlying DNA sequence, often influenced by environmental factors.
