Meiosis and Sexual Life Cycles

Flashcards covering the vocabulary of heredity, meiosis, and sexual life cycles based on Chapter 10 notes.

Heredity

The transmission of traits from one generation to the next.

Variation

The differences in appearance that offspring show from parents and siblings.

Genetics

The scientific study of heredity and variation.

Genes

Units of heredity made up of segments of DNA that are passed to the next generation via reproductive cells.

Gametes

Reproductive cells, specifically sperm and eggs, that pass genes to the next generation.

Locus

A specific position or location of a gene on a certain chromosome.

Somatic cells

All cells of the body except for gametes; in humans, these contain 46 chromosomes.

Asexual reproduction

A process in which a single individual passes all its genes to its offspring without the fusion of gametes, producing clones.

Clone

An individual that is genetically identical to its parent, produced through asexual reproduction.

Sexual reproduction

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

Karyotype

An ordered display of the pairs of chromosomes from a cell.

Homologous chromosomes (Homologs)

A pair of chromosomes of the same length and shape that carry genes controlling the same inherited characters.

Sex chromosomes

The X and Y chromosomes which determine the sex of the individual.

Autosomes

The 22 pairs of chromosomes in human somatic cells that are not involved in sex determination.

Diploid cell (2n)

A cell containing two sets of chromosomes; for humans, the diploid number is $2n = 46$.

Haploid cell (n)

A cell containing a single set of chromosomes, such as a gamete; for humans, the haploid number is $n = 23$.

Fertilization

The union of gametes, specifically the sperm and the egg.

Zygote

A fertilized egg that has one set of chromosomes from each parent and is therefore diploid.

Meiosis

A type of cell division that reduces the number of chromosome sets from diploid to haploid, resulting in four genetically distinct daughter cells.

Sporophyte

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

Gametophyte

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

Crossing over

The exchange of DNA segments between nonsister chromatids during Prophase I, producing recombinant chromosomes.

Chiasmata

X-shaped regions on each homologous pair where crossing over has occurred.

Synapsis

The state where homologous chromosomes physically connect and associate along their length allele by allele during Prophase I.

Synaptonemal complex

A zipper-like structure that forms during synapsis to attach homologous chromosomes together.

Independent assortment

The random orientation of homologous pairs of chromosomes at the metaphase plate during Metaphase I.

Recombinant chromosomes

Chromosomes that carry DNA from two different parents, resulting from crossing over.

Alleles

Different versions of genes created by mutations, which serve as the original source of genetic diversity.