BIOL 121 Chapter Notes -Microtubule Organizing Center, Spindle Apparatus, Sister Chromatids

• School: UBC
• Department: Biology
• Course: BIOL 121
• Professor: Carol Pollock

Document Summary

Eukaryotic chromosomes normally exist as extremely long, threadlike strands consisting of dna associated with globular proteins called histones. In eukaryotes, the dna-protein material is called chromatin. Each of the dna copies in a replicated chromosome is called a chromatid. Chromatids from the same chromosome are called sister chromatids they represent exact copies of the same genetic material. Each chromatid contains one long dna double helix. At the start of m phase, each chromosome consists of two sister chromatids that are attached to each other at the centromere. As mitosis begins, chromatin condenses to form a much more compact structure. During mitosis, the two sister chromatids separate to form independent chromosomes, and one copy of each chromosome goes to each of the two daughter cells. Chromosomes and centrosomes have already replicated during interphase. During prophase, the chromosomes condense into compact structures. Chromosomes first become visible in light microscope during prophase.