Mitosis and Meiosis - Part 2

Meiosis

A specialized type of cell division that produces gametes, reducing the chromosome number from diploid to haploid.

Gametes

Reproductive cells (e.g., sperm and eggs) that contain half the number of chromosomes found in somatic cells.

Zygote

The fertilized egg formed by the fusion of an egg and sperm cell, restoring the diploid chromosome number.

Homologous Chromosome Pairs

Pairs of chromosomes in a diploid cell, one inherited from each parent, that have the same genes in the same order.

Alleles

Different versions of a gene that can exist at a specific genetic locus.

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to an abnormal number of chromosomes.

Crossing-over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis, resulting in genetic variation.

Diploid (2n)

A cell containing two complete sets of chromosomes, one from each parent.

Haploid (n)

A cell containing a single set of unpaired chromosomes, typical of gametes.

Interkinesis

A stage between meiosis I and meiosis II where the spindle apparatus disassembles without DNA replication occurring.

Prophase I

The first stage of meiosis where homologous chromosomes pair and crossing-over occurs.

Metaphase I

The stage of meiosis where tetrads align at the metaphase plate before being separated.

Anaphase I

The stage of meiosis where homologous chromosomes are pulled to opposite poles by spindle fibers.

Telophase I

The stage of meiosis where the separated chromosomes reach the poles and the spindle apparatus disassembles.

Prophase II

The stage in the second meiotic division where chromosomes condense and a spindle apparatus forms again.

Anaphase II

The stage of meiosis II where sister chromatids are separated and move to opposite poles.

Telophase II

The final stage of meiosis where chromatids decondense, spindles disassemble, and nuclear envelopes reform around each set of chromosomes.

Karyotype

A display of the complete set of chromosomes in a cell, used to assess chromosomal abnormalities.