Biology Chapter 10: Meiosis and Sexual Life Cycles

Recombinant Chromosomes

A DNA molecule made in vitro (artificial insemination/test tube) with segments from different sources

Haploid

A cell containing only one set of chromosomes (n)

Diploid

A cell containing two sets of chromosomes (2n), one set inherited from each parent

Sex Chromosome

A chromosome responsible for determining the sex of an individual

Autosome

A chromosome that is not directly involved in determining sex; not a sex chromosome

Genes

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA; determines a certain trait

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape

Gamete

A haploid reproductive cell, such as an egg or sperm; gametes unite during sexual reproduction to produce a diploid zygote

Clone

A lineage of genetically identical individuals or cells An individual that is genetically identical to another individual

Meiosis

A modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication; it results in cells with half the number of chromosomes sets as the original cell

Homologous Chromosome

A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci; one homologous chromosome is inherited from the organism's father, the other from the mother

Locus

A specific place along the length of a chromosome where a given gene is located

Sexual Reproduction

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

Somatic Cell

Any cell in a multicellular organism except a sperm or egg or their precursors

Allele

Any of the alternative versions of a gene that may produce distinguishable phenotypic effects; variants of a gene Ex: gene=hair color; allele=brown hair

Meiosis II

Causes the cell to split again, resulting in four cells each with one-stranded chromosome

Independent Assortment

Formation of random combinations of chromosomes in meiosis and of genes on different pairs of homologous chromosomes by the passage according to the laws of probability of one of each diploid pair of homologous chromosomes into each gamete independently of each other pair

Meiosis I

The cell undergoes prophase, metaphase, anaphase, and telophase; this causes the cell to divide into two, and each cell ends up with one double-stranded chromosome

Asexual Reproduction

The generation of offspring from a single parent that occurs without the fusion of gametes (by budding, division of a single cell, or division of the entire organism into two or more parts); in most cases, the offspring are genetically identical to the parent

Crossing Over

The reciprocal exchange of genetic material between nonsister chromatids during prophase 1 of meiosis