Unit 5 - Heredity

Gametes

Sperms and eggs

Haploid

One set of chromosomes

Diploid

Two sets of chromosomes

Meiosis

A process that involves two rounds of cell division to produce haploid gametes and occurs in the ovaries or testes.

Interkinesis

A brief resting period before the second division of meiosis

Fertilization

Combines two haploid gametes to create a diploid

Meiosis I

Homologous chromosomes (one from each parent) separate

Meiosis II

Sister chromatids separate

Ploidy

The number of chromosome sets in a cell

Synapsis

The pairing of two homologous chromosomes during meiosis. 

Chiasmata

Structures formed when DNA molecules are broken and rejoined during crossing over

Karyotype

A visual representation of an individual’s chromosomes

Autosomal Inheritance

Traits are inherited on non-sex-linked chromosomes

Nuclear Chromosomes

Chromosomes that are located in the nucleus

Extranuclear genes

Genes that are located on the plasmids of organelles

Phenotype

The physical and observable characteristics of an organism

Genotype

The complete set of genetic material in an organism

alleles

Versions of a gene

Incomplete Dominance

Neither allele is completely dominant over the other

Monohybrid Cross

A genetic cross that focuses on one gene with two alleles. Punnett square with 4 squares.

Dihybrid Cross

A genetic cross that focuses on two genes, each with two alleles. Punnett square with 16 squares.

Codominance

Both alleles in a heterozygous genotype are fully expressed without blending

Multiple Alleles

A single trait is controlled by more than two different alleles in a population

Polygenic traits

When multiple genes influence a single trait

Wild Type

The typical form of a gene

Recombination frequency

The distance between the two genes on the chromosome.

Pedigree Charts

A diagram that shows how a trait or condition is inherited through generations

Phenotype plasticity

When individuals with the same genotype show different phenotypes in different environments

multifactorial

Influenced by both genetic and environmental factors.

Segregation

Homologous chromosomes are separated during anaphase I

Independent Assortment

Genes for different traits are inherited independently of each other

Random Fertilization

A sperm fertilizes an egg and create a random combination of alleles from both parents.

Nondisjunction

When chromosomes fail to separate properly during meiosis.

Maternal inheritance

The transmission of the mitochondrial genome from a mother to her children

Trisomy

Three copies of a chromosome. Ex- Down Syndrome