The Importance of Mitosis

The need to heal!

The need to grow!

DNA Made of nucleotides Phosphate sugar Nitrogen base Adenine Guanine Cytosine thymine

Coiling Uncoiled DNA called chromatin- between cell divisions Happens during cell division DNA wraps tightly around proteins called histones

Chromosomes Chromosome- consists of two identical halves connected together by a cnetromere Chromatid- a half of one chromosome. Contains one complete set of information Copies itself to make the other chromatid

How many chromosomes?? Each human diploid cell is 2N and contains 46 total 23 identical pairs ( 23 x 2 = 46 ) “homologous chromosomes” carry the same traits

How many chromosomes?? Egg and sperm cells only carry one set of 23 Each human haploid cell is “N” Egg and sperm combine to form 2N or 46 All other chromosomes are called autosomes Each human or animal cell has sex chromosomes XX or XY Define the sex of the organism

Cell Cycle G1 = cell grows S = DNA replication G2= Prepare to divide M= Mitosis INTERPHASE

2-4-8-16, etc… Quicktime video

Stages of Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis

Birth of a Brain Cell Quicktime movie

TWO REASONS FOR MITOSIS Healing/Repair Growth THE NEXT SLIDES ARE GRAPHIC

REASON FOR MITOSIS

Let the healing begin

Better

Much better

Mitosis in onion root tip Why onion root tip? Actively growing, lots of cells dividing (mitosis) Where exactly should you look on the microscope slide?

Cell division differences in plant vs animal cells Which is the animal cell and which is plant? Which stage of mitosis is being shown? CLEAVAGE FURROW CELL PLATE

Stages of mitosis id: slide #1

2 and 3

4 and 5

6 and 7

8 and 9

10, 11, 12

13, 14, 15

16, 17, 18

YOUR QUIZ ON MITOSIS IS TOM. Here’s what you need to be able to do…