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Flashcards for Biology - Meiotic Division and Genetic Variation
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Homologous Pairs
Pair of chromosomes which are the same size and shape and have the same genes at the same location. Human cells have 46 chromosomes – 23 homologous pairs.
Diploid (2N)
A cell with 2 sets of chromosomes (i.e., each of the homologous pairs) in each of its cells; somatic cells.
Haploid (N)
A cell with 1 set of chromosomes in each of its cells; (i.e., one chromosome from each homologous pair) all gametes – formed due to meiosis cell division.
Allele
Different forms of the same gene (ex. eye color).
Genetic Locus
The location of a particular gene on a chromosome.
Bivalent
A pair of homologous chromosomes.
Tetrads
The four chromatids in a bivalent.
Meiotic Division
Cell division that occurs in germline cells, producing gametes with half the number of chromosomes. Diploid (2N) to Haploid (N).
Meiosis I
The first stage of meiotic division involves the separation of homologous chromosomes.
Meiosis II
The second stage of meiotic division involves the separation of sister chromatids.
Synapsis
The pairing up of homologous chromosomes during Prophase I of meiosis.
Crossing Over
The exchange of genetic material between non-sister chromatids during Prophase I, leading to genetic variation. Occurs at the chiasmata.
Chiasmata
Area where there is a physical link between two non-sister chromatids during crossing over.
Independent Assortment
The random alignment of chromosomes during Metaphase I that increases the number of possible combinations of genetic material, leading to genetic variation.
Reduction Division
The process in meiosis I where the chromosome number is reduced from diploid (2N) to haploid (N).
Fertilization
The fusion of sperm (N) and egg (N) to restore the diploid number (2N) in the zygote.
Recombinant Chromosomes
Chromosomes that have undergone exchange of genetic material between chromosomes.
Genetic Variation
Differences in genotypes and phenotypes essential for species survival from diseases and environmental changes.
Mutation
A primary source of genetic variation in populations, involving changes in DNA sequencing.
Somatic Cells
Tissue cells that have pairs of homologous chromosomes and are diploid.
Germline Cell
Cells, in diploid state, that can divide by meiotic division.