BSC2010 - Chapter 17 Vocabulary

inheritance

The process by which physical and biological characteristics are transmitted from the parent (or parents) to the offspring

single-factor cross

a cross in which an experimenter observes one character

P generation

Parental generation, the first two individuals that mate in a genetic cross

F1 generation

offspring of the P generation

F2 generation

offspring of the F1 generation

monohybrid cross

cross between two parents that are heterozygous for one gene

genes

the biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein

alleles

different versions of a gene

dominant allele

An allele whose trait always shows up in the organism when the allele is present.

recessive allele

An allele that is hidden whenever the dominant allele is present

Mendel's Law of Segregation

the two alleles of a gene found on each of a pair of chromosomes segregate independently of one another into sex cells

genotype

genetic makeup of an organism

homozygous

An organism that has two identical alleles for a trait

heterozygous

An organism that has two different alleles for a trait

phenotype

physical characteristics of an organism

Punnett square

diagram showing the gene combinations that might result from a genetic cross

testcross

cross between an organism with an unknown genotype and an organism with a recessive phenotype

two-factor cross

Crosses in which the inheritance of two different traits are followed

dihybrid cross

cross between two organisms that are heterozygous for two traits

Mendel's Law of Independent Assortment

genes found on different chromosomes are sorted into sex cells independently of one another

chromosome theory of inheritance

A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

locus

Location of a gene on a chromosome

pedigree analysis

Chart showing one trait being carried over many generations

autosomes

Any chromosome that is not a sex chromosome

sex chromosomes

Chromosomes that determine the sex of an individual

X-linked genes

Genes found on the X chromosome.

sex-linked genes

Genes located on the sex chromosomes.

hemizygous

the presence of only one allele for a characteristic, as in X-linkage; hemizygosity makes descriptions of dominance and recessiveness irrelevant

Mendelian Inheritance

the basic principles associated with the transmission of genetic material, forming the basis of genetics, including the law of segregation and the law of independent assortment

Simple Mendelian Inheritance

an inheritance pattern involving a simple, dominant/recessive relationship that produces observed ratios in the offspring that readily obey Mendel's laws.

wild type alleles

prevalent alleles in a natural population

mutant alleles

alleles that have been altered by mutation

incomplete dominance

Situation in which one allele is not completely dominant over another allele

multiple alleles

A gene that has more than two alleles

codominance

A condition in which both alleles for a gene are fully expressed

gene interaction

interaction between genes at different loci that affect the same characteristic

epistasis

a gene at one locus alters the phenotypic expression of a gene at a second locus

pleiotropy

The ability of a single gene to have multiple effects.

discrete traits

traits that are clearly different from each other

quantitative traits

traits that show continuous variation (most traits, i.e.: height, intelligence, athleticism)

polygenic

describes a characteristic that is influenced by many genes