Meiosis

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Diploid Adjective

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[dip-loid]

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Diploid

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A cell containing two complete sets of homologous chromosomes, one set inherited from each parent, represented as 2N.

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Example: Human parents have diploid cells (46 chromosomes). They create sex cells (sperm and egg) with 23 chromosomes, which join to form a diploid baby with 46 chromosomes.

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Haploid Adjective

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[hap-loid]

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Haploid

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A cell containing a single, unpaired set of chromosomes, and therefore only a single set of genes, represented as N.

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Example: This image shows that a haploid cell (n) contains a single set of chromosomes, with only one copy of each type.

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Homologous Adjective

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[ho-mol-uh-gus]

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Homologous

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Refers to a pair of chromosomes, one from each parent, that have the same size, shape, and gene sequence.

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Example: This image shows a pair of homologous chromosomes, one from each parent (red and blue), which have exchanged genetic material through recombination during meiosis.

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Meiosis Noun

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[my-oh-sis]

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Meiosis

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A type of cell division that reduces the chromosome number by half, creating four haploid cells from one diploid cell.

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Example: This diagram shows the process of meiosis, where one parent cell divides twice to produce four unique haploid daughter cells, each with half the number of chromosomes.

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Tetrad Noun

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[tet-rad]

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Tetrad

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A structure containing four chromatids that forms during meiosis when replicated homologous chromosomes pair up.

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Example: This diagram shows a tetrad, which is a pair of homologous chromosomes stuck together. Since each chromosome has two parts (sister chromatids), the whole structure has four chromatids.

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Crossing-Over Noun

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[kros-ing oh-ver]

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Crossing-Over

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

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Example: During meiosis, paired homologous chromosomes (one from each parent) exchange segments of their DNA, creating new combinations of genes on the resulting chromosomes.

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Gamete Noun

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[gam-eet]

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Gamete

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A mature haploid reproductive cell, such as a sperm or egg, that unites with another to form a zygote.

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Example: This diagram shows that gametes, like sperm and egg cells, are haploid (n) and combine during fertilization to create a diploid (2n) fertilized egg.

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Chromatid Noun

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[kroh-muh-tid]

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Chromatid

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One of two identical sister parts of a duplicated chromosome, joined together by a common centromere before cell division.

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Example: This image shows that after a chromosome replicates, it consists of two identical copies called sister chromatids, which are joined together at the centromere.

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Gene Linkage Noun

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[jeen ling-kij]

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Gene Linkage

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The tendency for genes located close together on the same chromosome to be inherited together during meiosis.

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Example: This diagram shows that linked genes are located close together on the same chromosome, while unlinked genes are on different chromosomes or far apart.

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Gene Map Noun

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[jeen map]

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Gene Map

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A diagram showing the relative locations of specific genes on a chromosome, often determined by recombination frequencies.

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Example: A gene map shows the specific location of genes on a chromosome, linking them to particular traits like eye color or height.