genetics terms 1234

Synteny

two or more genes are located on the same chromosome and are physically linked

Genetic Linkage

is the phenomenon that genes close together on a chromosome tend to be transmitted as a unit, which influences inheritance patterns

linkage groups

they contain a group of genes that are linked together

Bivalents

Replicated sister chromatid homologs associate

crossing over

occurs during prophase I of meiosis

recombinant offspring

those that have been produced due to a crossover event during gamete formation in (at least) one of their parents

map units

they are also referred to as centiMorgans (cM)

Interference

(I) is expressed as I = 1 − C

Maternal effect

refers to an inheritance pattern for certain nuclear genes in which the genotype of the female parent directly determines the phenotype of the offspring

Epigenetic inheritance

refers to a pattern in which a modification occurs to a nuclear gene or chromosome that alters gene expression and is passed from cell to cell

dosage compensation

is to offset differences in the number of active sex chromosomes

Lyon hypothesis

The mechanism of dosage compensation in mammals

Genomic imprinting

is a phenomenon in which a segment of DNA is marked and the effect is maintained throughout the life of the organism inheriting the marked DNA

monoallelic expression

Depending on how the genes are “marked”, the offspring expresses either the maternally-inherited or the paternally-inherited allele

Extranuclear inheritance

refers to inheritance patterns involving genetic material outside the nucleus

maternal inheritance

the pigmentation of the offspring depended solely on the maternal parent and not at all on the paternal parent

heteroplasmy

variegated phenotypes

Mendelian inheritance

inheritance patterns that obey two laws: Law of segregation, and Law of independent assortment

Incomplete Dominance

heterozygote exhibits a phenotype that is intermediate between the corresponding homozygotes

Sex-linked genes

genes found on one of the two types of sex chromosomes, but not both

Sex-influenced Inheritance

Traits where an allele is dominant in one sex but recessive in the opposite sex

Sex-limited Inheritance

Traits that occur in only one of the two sexes

Pleiotropy

Multiple effects of a single gene on the phenotype of an organism

X-linked genes

Genes that are physically located on the X chromosome