Chapter 13: Sexual Reproduction and Meiosis

Vocabulary flashcards covering the key terms, life cycles, stages of meiosis, and mechanisms of genetic variation from Chapter 13.

Asexual reproduction

A mode of reproduction where a single parent produces genetically identical offspring without the fusion of gametes.

Clone

A group of genetically identical individuals produced from a single parent through asexual reproduction.

Sexual reproduction

A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from both parents.

Somatic cell

Any biological cell forming the body of an organism (excluding gametes), containing $23$ pairs of chromosomes in humans.

Karyotype

An ordered, visual display of the chromosome pairs from a cell arranged by size and shape.

Homologs (Homologous chromosomes)

A pair of chromosomes that possess the same length, centromere position, and gene loci, with one inherited from each parent.

Sex chromosomes

Chromosomes that determine the sex of an individual, distinguished from autosomes.

Autosomes

All the chromosomes in a genome that are not directly involved in determining sex.

Diploid ($2n$)

A cell or condition containing two complete sets of chromosomes, one inherited from each parent, characteristic of somatic cells.

Haploid ($n$)

A cell containing a single set of unpaired chromosomes, characteristic of gametes produced by meiosis.

Fertilization

The union of haploid gametes (sperm and egg) that produces a diploid zygote.

Zygote

The diploid cell resulting from the fusion of male and female gametes during fertilization.

Alternation of generations

A plant sexual life cycle that includes both multicellular diploid (sporophyte) and multicellular haploid (gametophyte) stages.

Gametophyte

The multicellular haploid generation in plants that produces haploid gametes by mitosis.

Sporophyte

The multicellular diploid generation in plants that produces haploid spores by meiosis.

Meiosis I

The first division of meiosis that separates homologous chromosomes, transitioning the cell from diploid to duplicated haploid.

Meiosis II

The second division of meiosis that separates sister chromatids, transitioning the cell from duplicated haploid to haploid.

Synapsis

The pairing and physical connecting of replicated homologous chromosomes during prophase I of meiosis.

Crossing over (Recombination)

The reciprocal exchange of genetic material between non-sister chromatids during prophase I of meiosis.

Chiasma

The X-shaped microscopic region where crossing over has occurred between homologous non-sister chromatids.

Independent assortment

The random orientation and segregation of maternal and paternal homologous chromosome pairs during metaphase I, generating $2^n$ possible combinations.

Random fertilization

A source of genetic variation in which any sperm can fuse with any unfertilized egg, yielding approximately $8\text{ million} \times 8\text{ million} = 64\text{ trillion}$ possible diploid combinations in humans.