HMB265 Section 1 Flashcards

Blended inheritance

The hypothesis that offspring inherit a mixture or blend of traits from both parents.

Uniparental inheritance

The hypothesis that offspring resemble only one of their two parents for a particular trait.

Hybrid

An offspring produced from parents with different genetic characteristics.

Reciprocal cross

Two crosses in which the sexes of the parents are reversed to determine whether inheritance depends on which parent contributes a trait.

Hybrid

An individual derived from two genetically different parents.

Monohybrid

An individual or cross involving one heterozygous locus, such as Aa or AaBB.

Dihybrid

An individual or cross involving two heterozygous loci, such as AaBb.

True-breeding

An organism that is homozygous at the locus or loci being considered and therefore consistently passes the same allele to its offspring.

Testcross

A cross between an individual with an unknown genotype and an individual that is homozygous recessive.

Reciprocal recessive epistasis (complementary gene interaction) + phenotypic ratio

when homozygous recessive allele of one gene masks the dominant allele of the other gene (RATIO = 9:7)

Recessive epistasis + phenotypic ratio

when homozygous recessive allele of one gene masks both alleles of another gene (RATIO = 9:3:4)

Dominant epistasis I + phenotypic ratio

dominant allele of one gene hides effects of both alleles of the other gene (RATIO = 12:3:1)

Dominant epistasis II + phenotypic ratio

dominant allele of one gene hides effects of dominant allele of the other gene (RATIO = 13:3)

Reciprocal dominant epistasis + phenotypic ratio

One dominant allele at either gene masks the effects of even homozygous recessive gene (RATIO = 15:1)

Pleiotropy

single gene determines more than one distinct and seemingly unrelated characteristics

• embryonic lethality is an example of this

true breeding

an organism consistently passes down specific physical traits to its offspring generation after generation - HOMOZYGOUS for the trait

Homologues

Same set of genes, different alleles

Sister chromatids

Same genes, exact same alleles (replica)

Non-homologues

Completely unrelated sets of genes

Haploid

Cells that carry only a single chromosome set

Diploid

Cells that carry two matching chromosome sets

Gametogenisis

Process by which germ cells differentiate into gametes, which pass along a haploid set of chromosom

Somatic cells

divide mitotically and make up vast majority of organism’s tissues

Germ cells

specialized role in the production of gametes

Nondisjunction

failed chromosome separation

syntenic genes

genes located on the same chromosome

linked genes

syntenic genes close together, cannot sort independently

chiasmata

regions in which nonsister chromatids of homologous chromosomes cross over each other

genetic recombination

mixing of genes during gametogenesis produces gametes with combinations of genes that are different from the combinations received from parents

Chi-square test

X² = Σ(O-E)²/E ; asses the likelihood that a deviation from expectation is due to chance

What is the maximum a recombination frequency can be?

50% which means the genes are unlinked (0% RF = complete linkage and we will only see parental types)

Hardy-Weinburg Equilibrium Conditions

NO: Mutation, Migration, genetic Drift, Non-random mating, Selection

If you are calculating allele frequencies and it is NOT H-W eq, what do you use?

AF = # of a particular allele/total # of alleles in a population

Polymorphism

detectable change in a given locus/gene (what makes an allele and allele)

Dominant negative

The mutant allele produces an abnormal protein that interferes with the function of the normal protein made by the other allele.

Haploinsufficiency

One allele is lost or nonfunctional, and the remaining normal allele cannot produce enough functional protein to meet the body's needs.

Redundant gene action

for a trait with 2 genes, either dominant allele is sufficient to produce the wild-type phenotype (i.e. TtRr = wild type, but Ttrr or ttRr would also produce the wild type)

How to calculate interferance?

Interference = 1 - COC

How to calculate COC?

COC = observed double cross overs/expected double cross overs

How to calculate expected double cross overs?

multiply the frequency of recombination between 2 different recombinants

Null

produces no functional gene product

Complementation testing

a genetics test used to determine whether two recessive mutations are in the same gene or in different genes

ex. Parent 1: (aaBB) —> white eyes

Parent 2: (AAbb) —> white eyes

Cross them: (AaBb) —> red eyes bc they have at least one functional copy of each gene