D3.2 Inheritance

What is a genotype?

The combination of alleles in an organism.

What are alleles?

Variations of the same gene.

What does homozygous mean?

A genotype with the same allele.

What does heterozygous mean?

A genotype with different alleles.

What is phenotype?

Phenotype refers to observable traits of an organism.

What defines a dominant allele?

If present in the genotype, it will be expressed and codes for a functional protein.

What defines a recessive allele?

Will only be expressed if present as homozygous recessive and codes for a malfunctioning protein.

What is phenotypic plasticity?

The ability of an organism’s phenotype to change according to environmental conditions.

What causes phenylketonuria?

A recessive allele on chromosome 24 that impairs the body's ability to break down phenylalanine.

What is a carrier in genetics?

A heterozygous individual that carries an allele for a disease but does not express symptoms.

What are single-nucleotide polymorphisms?

Variation at a single position in the DNA sequence.

What is a gene pool?

All the genes of all individuals in a sexually reproducing population.

What is codominance?

Where two different alleles are both dominant and expressed simultaneously.

What blood type represents codominance?

Type AB blood

What is incomplete dominance?

A genetic situation where neither allele is dominant or recessive, resulting in a blended phenotype.

What determines sex in humans?

The presence of X and Y chromosomes; males are XY, females are XX.

Characteristics of X chromosomes

Relatively large, centromere near the middle, all humans must have at least one

Characteristics of Y chromosomes

Smaller, centromere near one end, only present in males

What is Sex linkage?

A mutation on the sex chromosome that leads to disease

What is hemophilia?

A sex-linked (X-chromosome) recessive genetic disorder that prevents blood from clotting.

What is Polygenic Inheritance?

Phenotypes determined by numerous genes (e.g. height, skin color)

What does segregation mean in genetics?

The separation of alleles of a gene during the formation of gametes.

What is independent assortment?

The segregation of alleles of two genes, where the outcome of one gene does not affect the other.

What is a gene locus?

The specific location of a gene on a chromosome.

What is recombination in genetics?

The process by which new combinations of alleles are formed in offspring.

What is Gene Linkage?

Genes are physically linked and do not assort independently

What are Recombinants?

Individual with different combination of alleles/traits from either parent