Genetics

Type shi

Additive gene interaction

Four distinct F2 phenotypes. 9:3:3:1

recessive epistasis

homozygous recessive allele of one gene masks both alleles of another gene. 9:3:4. Labrador example

Reciprocal recessive epistasis

homozygous recessive allele of each gene masks the dominant allele of the other gene. 9:7. flower color example.

Dominant epistasis I

Dominant allele of one gene hides effects of both alleles of the other gene. 12:3:1. Squash example.

Dominant epistasis II

dominant allele of one gene hides effects of dominant allele of other gene. 13:3. chicken example

Reciprocal dominant epistasis

dominant allele of each gene masks the effects of recessive allele of the other gene. 15:1. Maize example.

Pleiotropy

A single gene determines multiple traits.

Delayed lethality

recessive alleles result in death of homozygotes later due to genetic defect. Example Tay Sachs disease.

heterogenous trait

caused by a mutation in one of many different genes.

Sex (x) linked recessive

more males affected, often skips generations, no father to son transmission.S

Sex (X) linked dominant

affected fathers pass trait to all daughters but no sons, but sons can have the trait if the mother has it.

Mitochondrial Inheritance pattern

Passed from affected mothers to all offspring: affected fathers do not transmit trait.

Interphase

cell spends most of its life here, cell grows, dna replicates, each chromosome gains a sister chromatid.

G1 phase

Interphase, gap before duplication

S phase

DNA synthesis and chromosome duplicationG

G1 Phase

Interphase, gap before mitosis

What gene on the Y chromosome determines maleness

SRY

Psuedoautosomal regions (PARS)

two ends of the y and X chromosomes which allow dissimilar X and Y chromosomes to pair with each other during Meoisis I.

XO pattern

Female with turner syndrome (sterile)

XXY pattern

Male with Klinefelter syndrome (Sterile)

heterogametic sex

sex having two different sex chromosomes, inverse called homogametic sex.

Crisscross inheritance

males inherit trait from mother, females inherit trait from fathers.

hemizygous

diploid cells have half number of alleles carried by the female on her two X chromosome

Nondisjunction

failure in chromosome segregation

Dosage compensation

The inactivation of one X chromosome in females due to proteins being made present in the same amount in both female and male cells

Barr body

X chromosome being inactivated

lyonization

another name for x chromosome inactivation

sex limited traits

affects a structure or process that is found in one sex but not the other.

Sex influenced traits

show up in both sexes, but character of such traits differs because of hormonal differences. Example balding.

Polymorphic

Genes that have more than one common allele

Polygenic

influenced by multiple genes. Continous traits called complex traits.