Genetic Traits, Variation, and Inheritance Patterns

Genetic Variation

Differences in traits among individuals.

Monozygotic Twins

Identical twins from one fertilized egg.

Dizygotic Twins

Fraternal twins from two fertilized eggs.

Gametes

Haploid sex cells with 23 chromosomes.

Homologous Chromosomes

Pairs with same genes, different alleles.

Alleles

Different versions of a gene.

Genotype

An organism's genetic makeup.

Phenotype

Observable traits of an organism.

Homozygous

Two identical alleles for a trait.

Heterozygous

Two different alleles for a trait.

Punnett Square

Tool to predict offspring genotype ratios.

Dominant Allele

Masks effects of recessive alleles.

Recessive Traits

Traits appearing when both alleles are recessive.

Codominance

Both traits expressed equally in phenotype.

Incomplete Dominance

Blended traits in the phenotype.

X-linked Traits

Traits carried on the X chromosome.

X-linked Recessive Traits

More common in males; females can be carriers.

X-linked Dominant Traits

Affect both genders; males often more severely affected.

Meiosis

Produces four genetically diverse haploid cells.

Mitosis

Produces two identical diploid daughter cells.

Crossing Over

DNA exchange between homologous chromosomes during meiosis.

OCA2 Gene

Regulates melanin production affecting eye color.

TYR Gene Mutation

Causes albinism by impairing melanin production.

Melanin

Pigment controlling skin, hair, and eye color.