1.46k likes | 2.51k Views
Modern Biology. Chapter 8: Cell Reproduction. 8-1: Chromosomes. Chromosome structure DNA coiled very tightly around proteins called histones. chromosome. Sister chromatids. Centromere. Numbers of chromosomes….
E N D
Modern Biology Chapter 8: Cell Reproduction
8-1: Chromosomes • Chromosome structure • DNA coiled very tightly around proteins called histones
chromosome Sister chromatids Centromere
C:\Projects\Holt-Rinehart-Winston\HRWScience\HRWScience\Modern_Biology\Ch08\60121.htmlC:\Projects\Holt-Rinehart-Winston\HRWScience\HRWScience\Modern_Biology\Ch08\60121.html
Chromosome numbers • humans have 46 individual chromosomes in 23 pairs • homologous pairs: each member of a pair codes for the same trait, but may code for different values of the trait • both will code for eye color • one may carry code for green, the other blue
Human Chromosome numbers • of the 46 chromosomes, • 44 are autosomes • autosome: non-sex chromosome • 2 are sex chromosomes • sex chromosome: chromosomes that determine the sex of an individual
Human sex determination • XX- female • XY- male
Chromosome Number and Cell Type • diploid cells • diploid: cell that contain homologous pairs • most cells in human body • get one set from mom and the other from dad • 2n
Chromosome Number and Cell Type • haploid cells • cell containing only one of each pair of homologous chromosomes • half the number of chromosomes • n • a.k.a.: gametes • Sperm and eggs
Diploid v. Haploid Diploid chromosomes exist in pairs Haploid Chromosomes don’t exist in pairs
The making of an individual n (egg) + n (sperm) 2n (individual with full set)
Cell Division For autosomal cells
Cell division in prokaryotes • binary fission: division of prokaryotic cell into two new cells • produces genetically identical individuals
Cell division in eukaryotes • the cell cycle: repeating series of events in which new cells are made • Has three main functions
A Mathematical Question Do we divide or multiply?
http://www.youtube.com/watch?v=nPG6480RQo0&feature=related • http://www.youtube.com/watch?v=nPG6480RQo0&NR=1
Dolly • Dolly was the first mammal to be successfully cloned.
G0 cell that has exited the cell cycle • nerve cells are permanently here • they are unable to divide again
Drugs and alcohol kill brain cells- it’s not a myth • DO NOT DO STUPID THINGS THAT KILL THEM • Actually, they kill all of your cells, brain cells just don’t grow back.
Mitosis • M phase • Period of nuclear division • four phases
Anaphase Metaphase Late Prophase Telophase & Cytokinesis Early Prophase Interphase (G1, S, G2) Cytokinesis
http://www.youtube.com/watch?v=4PKjF7OumYo&feature=player_embedded#http://www.youtube.com/watch?v=4PKjF7OumYo&feature=player_embedded#
Prophase • DNA coils into chromosomes • Centrioles form • Spindle fibers come from centrioles • nucleolus and nuclear envelope disintegrated • longest of the phases