Meiosis and Sexual Life Cycles – Core Vocabulary

A set of vocabulary flashcards covering fundamental terms from Chapter 13 (Meiosis and Sexual Life Cycles).

Heredity

The transmission of traits from one generation to the next.

Variation

Differences in appearance or traits among offspring, parents, and siblings.

Genetics

The scientific study of heredity and variation.

Gene

A unit of heredity; a DNA segment that codes for a specific trait.

Locus

The specific physical location of a gene on a chromosome.

Chromosome

A DNA molecule packaged with proteins; carries genetic information.

Somatic Cell

Any body cell other than gametes and their precursors; in humans, 46 chromosomes.

Gamete

A reproductive cell (sperm or egg) that is haploid and transmits genes to offspring.

Asexual Reproduction

Reproduction involving one parent, producing genetically identical offspring (clones).

Clone

A group of genetically identical individuals derived from one parent.

Sexual Reproduction

Reproduction involving two parents that combine genes to produce genetically unique offspring.

Life Cycle

The sequence of stages from one generation to the next in an organism’s reproductive history.

Karyotype

An ordered display of the chromosomes of a cell, arranged in pairs.

Homologous Chromosomes (Homologs)

A pair of chromosomes of the same length, shape, and gene content—one maternal, one paternal.

Autosome

Any chromosome that is not a sex chromosome; humans have 22 pairs.

Sex Chromosomes

Chromosomes (X and Y) that determine an individual’s sex.

Diploid (2n)

A cell with two sets of chromosomes; for humans, 2n = 46.

Haploid (n)

A cell with one set of chromosomes; for humans, n = 23.

Fertilization

Fusion of haploid gametes to form a diploid zygote.

Zygote

A fertilized egg; diploid cell formed by union of sperm and egg.

Meiosis

A two-division process that reduces chromosome number by half, producing four haploid cells.

Mitosis

Cell division that conserves chromosome number, producing genetically identical daughter cells.

Alternation of Generations

Life cycle in plants/algae with both multicellular diploid (sporophyte) and haploid (gametophyte) stages.

Sporophyte

The diploid, spore-producing multicellular stage in plants/algae.

Gametophyte

The haploid, gamete-producing multicellular stage in plants/algae.

Spore

A haploid cell produced by meiosis in the sporophyte that can develop into a gametophyte by mitosis.

Sister Chromatid

One of two identical copies of a duplicated chromosome, joined at the centromere.

Sister Chromatid Cohesion

Protein-mediated attachment holding sister chromatids together until separation.

Synapsis

The pairing of homologous chromosomes during prophase I of meiosis.

Synaptonemal Complex

Protein structure that tightly holds homologs together during synapsis.

Crossing Over

Exchange of DNA segments between nonsister chromatids of homologs during prophase I.

Chiasma (plural Chiasmata)

Visible X-shaped crossover site where homologous chromatids have exchanged DNA.

Independent Assortment

Random orientation of homologous chromosome pairs at metaphase I, generating genetic variation.

Recombinant Chromosome

A chromosome created by crossing over, containing DNA from both parents.

Random Fertilization

Chance union of any sperm with any egg, greatly increasing potential genetic combinations.

Cohesins

Proteins that hold sister chromatids together and are cleaved at specific stages of meiosis or mitosis.

Reductional Division

Meiosis I, where homologous chromosomes (but not sister chromatids) separate, halving chromosome number.

Allele

A variant form of a gene arising from mutation.

Genetic Variation

Diversity in gene frequencies within a population, produced by mutation, meiosis, and fertilization.