Biology Chapter 12- Genes & Traits

Trait

A characteristic that can be observed in an organism.

Allele

Different forms of a gene that can exist at a specific locus on a chromosome

Gene

A strand of DNA that encodes a trait

Law of segregation

During the formation of gametes, the two alleles for a trait segregate from one another, so that each gamete carries only one allele for each gene

Law of Dominance

In a heterozygous individual, one allele may mask the expression of another

Law of Independent Assortment

Genes of different traits assort independently of one anotehr in the formation of gametes

Genotype

The genetic makeup of an organism, represented by the alleles it posseses.

Phenotype

The observable physical traits of an organism

Homozygous

An organism with two identical alleles for a particular trait

Heterozygous

An organism with two different alleles for a particular trait

Dominant

An alelle that expresses its trait even in the presence of a recessive allele

Recessive

An allele that only expresses its trait when two copies are present

Punnett square

A diagram uses to predict the outcome of a genetic cross by showing the possible combinations of alleles from the parents

P1 Generation

The parental generation in a genertic cross

F1 Generation

The first filial generation

F2 Generation

The second filial generation

Monohybrid Cross

A genetic cross that examines the inheritance of a single trait

Dihybrid cross

A genetic cross that examines the inheritance of two traits

Probability

The likelihood of a particular gene occuring

Incomplete Dominance

A form of inheritance where both genotypes are somewhat shown to create a new trait

Codominance

When both genotypes are completely shown

Multiple allelic trait

Traits controlled by more than two alleles

Polygenic Trait

Traits controlled by multiple genes

Sex-Linked Trait

Traits that are associated with genes located on sex chromosomes, often leading to different inheritance patterns in males and females. An example is color blindness, which is more common in males than females.

Who is the father of genetics

Gregor Mendel

What is an allele?

Alternate form of a gene

Combination of alleles called?

Genotype

Pairs of genes seperate during the formation of…

gametes