Unit 5 – Meiosis & Heredity Study Guide

Asexual Reproduction

Reproduction involving one parent, no gametes, producing genetically identical offspring.

Sexual Reproduction

Reproduction involving two parents, using gametes, resulting in genetic variation.

Gametes

Reproductive cells: sperm (male) and egg (female), used in sexual reproduction.

Chromosomes

Structures containing genetic information; humans have 23 pairs.

Diploid

A cell containing two sets of chromosomes (2n), like somatic cells.

Haploid

A cell containing one set of chromosomes (n), like gametes.

Karyotype

An image showing chromosomes arranged in homologous pairs.

Homologous Pair

A pair of chromosomes, one from each parent, that are similar in shape and size.

Fertilization

The fusion of haploid sperm and egg to form a diploid zygote.

Zygote

A fertilized egg, which is a diploid cell.

Meiosis

A process that produces four genetically unique haploid cells through two divisions.

Prophase I

The stage in meiosis I where homologous chromosomes pair and crossing over occurs.

Tetrad

A group of four chromatids formed during meiosis I.

Crossing Over

The exchange of DNA between homologous chromosomes during meiosis.

Metaphase I

Stage of meiosis I where homologous pairs line up in the center of the cell.

Independent Assortment

The random arrangement of chromosomes during metaphase I, increasing genetic diversity.

Anaphase I

The stage in meiosis I where homologous chromosomes are pulled apart.

Telophase I

The end of meiosis I when two haploid cells form, chromosomes still duplicated.

Meiosis II

A process similar to mitosis that separates sister chromatids into four haploid cells.

Dominant

An allele that expresses its trait even when only one copy is present.

Recessive

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

Heredity

The passing of traits from parents to offspring.

Trait

A specific version of a character that can be inherited.

Character

A heritable feature, like height or eye color.

Allele

Different versions of a gene found at the same locus.

Locus

The specific location of a gene on a chromosome.

Law of Segregation

The principle stating that allele pairs separate during gamete formation.

Law of Independent Assortment

The principle that genes for different traits separate independently of one another.

Pedigree

A chart used to trace inheritance patterns of traits in families.

Incomplete Dominance

A genetic situation where a heterozygous phenotype is a blend of the two homozygous phenotypes.

Codominance

A genetic situation where both alleles in the genotype are fully expressed.

Polygenic Inheritance

A trait influenced by multiple genes, resulting in a range of phenotypes.

Multiple Alleles

The existence of more than two alleles for a genetic trait.

DNA

The molecule that