GB1 - Ch. 14 Mendel Genetics Vocab

heredity

inheritance, transmission of traits from parents to offspring

trait

observable characteristic

blending inheritance hypothesis

traits of a mother and father blend together to form traits in their offspring

inheritance of acquired characters hypothesis

traits are modified through use and then passed on from parents to their offspring

model organism

species that is used for research because it is easy to work with and conclusions drawn from studying it may apply to many other species

polymorphic trait

A trait for which more than one form of an allele commonly appears in a population.

self fertilization

The fusion of two gametes produced by the same individual to form offspring. Also called selfing.

cross fertilization

A mating between two individuals that is used for genetic analysis.

autosomal inheritance

The patterns of inheritance of any genes not on a sex chromosome. These are the “standard” patterns of inheritance.

What Mendel studied

genotype

A listing of the alleles of particular genes in an individual.

phenotype

An individual’s observable traits.

homozygous

Having two of the same allele.

heterozygous 

Having two different alleles.

dominant allele

allele that produces the same phenotype in heterozygous and homozygous genotypes.

recessive allele

allele that produces its phenotype only in homozygous genotypes.

pure line

Individuals identical in phenotype that, when crossed, produce offspring that all have the same phenotype.

homozygous

hybrid

Offspring from crosses between homozygous parents with different genotypes.

heterozygous

reciprocal cross

cross in which the phenotypes of the male and female are reversed compared with a prior cross.

test if the sex of the parent influences transmission of the trait

testcross

cross of a homozygous recessive individual and an individual with the dominant phenotype but unknown genotype

determine whether a parent with a dominant phenotype is homozygous or heterozygous

x-linkage

gene located on the X chromosome or a trait associated with a gene on the X chromosome. Also known as X-linked.

show different patterns of inheritance in males and females

y-linkage

gene located on the Y chromosome or a trait associated with a gene on the Y chromosome. Also known as Y-linked.

most determine male-specific development

parental generation

individuals used in initial cross

progeny

offspring

F1 generation

progeny from parental generation

first filial

monohybrid cross

A mating like between parents that each carry two different genetic determinants for the same trait

produces a hybrid for a single trait

particulate hypothesis

inheritance is based on genes that do not blend together in offspring but instead remain separate, or particle-like.

principle of segregation

two members of each gene pair must segregate into different gamete cells during the formation of eggs and sperm

result in each gamete contains one allele of each gene

genetic model

set of hypotheses that explains how a particular trait is inherited

Mendel’s rules

independent assortment hypothesis

two alleles of each gene would be sorted into gametes independently of each other

dependent assortment hypothesis

transmission of one particular allele would be tied to or depend on the transmission of another

dihybrid cross

A mating between two homozygous parents that differ in alleles of two different genes. Produces dihybrid offspring.

usually continued through the F2 generation

testcross

parent with a dominant phenotype but unknown genotype is crossed with a parent that contributes only recessive alleles.

By analyzing the phenotypes of the offspring, the unknown parental genotype can be determined.

transmission genetics

patterns that occur as alleles pass from one generation to the next

locus

allele particular location on chromosome

wild type

most common phenotype(s) seen in a wild population.

mutation

heritable change in gene

mutant

individual with an unusual phenotype due to a mutation

x-linked gene

gene on X chromosome

y-linked gene

gene on y chromosome

sex-linked gene

gene being located on either sex chromosome

sex linked inheritance

Inheritance patterns observed in genes carried on sex chromosomes. In this case, females and males have different numbers of alleles of a gene. Often creates situations in which a trait appears more often in one sex.

X linked inheritance

Inheritance patterns for genes located on the X chromosome

Y linked inheritance

Inheritance patterns for genes located on the Y chromosome.

autosomal inheritance

The inheritance patterns that occur when genes are located on autosomes rather than on sex chromosomes.

observed by Mendel

linkage

tendency of alleles of particular genes on same chromosome to be inherited together

recombinant

Possessing a new combination of alleles

genetic map

diagram showing the relative positions (loci) of genes along a particular chromosome

multiple allelism

existence of more than two common alleles of the same gene

complete dominance

form of dominance in which the phenotype of a heterozygote is indistinguishable from the phenotype of one of the homozygotes

incomplete dominance

form of dominance in which heterozygotes have a phenotype that is between the phenotypes of the two different homozygous parents

codominance

form of dominance in which simultaneous expression of the phenotype associated with each of the alleles in a heterozygote

pleiotropic

gene that influences many traits

gene interaction

When two or more genes influence a single trait

epistasis

gene interaction in which expression of a phenotype associated with a particular genotype of one gene can be completely masked by a particular genotype of a different gene

environmental effects

anything that influences phenotypes other than the genotype

discrete traits

traits that are clearly different from each other

quantitative traits

types of continuously varying traits that don’t fall into distinct categories

often plotted to produced a normal, bell shaped curve

polygenic trait

each of many different genes adds a small amount to the value of the trait

exhibits continuous variation rather than distinct phenotypes.

mode of transmission

trait as autosomal or sex-linked and the type of dominance of the allele

pedigree

family tree of affected and unaffected individuals

carriers

Heterozygous individuals who do not have an inherited disease but carry a recessive allele for it