BIOL 2301 Lecture 12: Chapter 5 - Human Chromosomes
27 Feb 2018
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Document Summary
Humans have 46 chromosomes in 23 pairs. Chromosome painting: a method of hybridization in which chromosome are painted". Chromosome staining happens when cells are arrested in metaphase. Giemsa staining gives characteristic bands on each chromosome and allows for chromosome identification. Karyotype: chromosomes are arranged systematically in pairs from longest to shortest. Gene density is not highly correlated with chromosome size. Dna complementary to these sequences is synthesised and labeled with a specific dye. Probes are allowed to hybridize to a prep of metaphase chromosomes. Chromosomes with no centromeres or two centromeres are genetically unstable. Human chromosomes are linear with a single centromere. Chromosomes are often classified according to the position of the centromere which determines the appearance of the daughter chromosomes as they separate from each other in anaphase. A chromosome without a centromere = acentric centromere. A chromosome with 2 centromere = dicentric centromere. Dosage compensation adjusts the activity of x-linked genes in females.
