Chromosomes


Histones
	proteins that DNA wraps around
	prevents DNA from tearing during cell division
	maintains shape of chromosomes
Non-histone proteins
	do not participate in packing DNA
	control activity of specific regions of the DNA
Sister Chromatids (Chromatid)
	form when DNA makes a copy of itself
Centromere
	constricted area of each chromatid
	holds the two chromatids together
Kinetochore
	disk shaped protein that surrounds the centromere
	fibers radiate from kinetochore
Chromosome numbers
	Diploid number
		2 complete sets of DNA
		2n
		humans-46
	Haploid number
		one complete set of chromosomes
		1n
		gametes (egg & sperm)
		23 chromosomes (human)
Fertilization
	joining of egg and sperm
	zygote
		result of fertilization
		single cell
		diploid
		first cell of new individual
Sex Chromosomes
	determine gender
	humans-X or Y
		female- XX
		male- XY
Autosomes
	all other chromosomes
Homologous Pairs
	matched sets of autosomes
	similar in size, shape, and genetic makeup
	each- homologue

	
	

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