1. Cell Division
Chapter 2
Section 3

2. The Cell Cycle
The regular sequence of growth and division that cells undergo

3. Stage 1: Interphase Growth DNA Replication Cell grows to mature size
Endoplasmic reticulum produces more ribosomes
Produces enzymes
Mitochondria and chloroplasts duplicate
Replication process
Cell makes copies of DNA in nucleus
Each cell has 2 identical copies of the DNA
One set will go to each daughter cell

4. Stage 1: Interphase Preparation for Division
Cell produces structures needed for cell division
Cell is now ready to divide
Longest phase of cell division

5. State 2: Mitosis Mitosis: Four parts of Mitosis Cell nucleus divides
One copy of the DNA distributed to each daughter cell
Four parts of Mitosis
Prophase
Metaphase
Anaphase
Telophase

6. Stage 2: Mitosis Prophase Chromatin condense
Look like tiny rods
Chromatid
Since DNA is replicated there are 2 rods
chromosome
Two strands tied together by a centromere
Nuclear membrane breaks down

7. Stage 2: Mitosis Metaphase
Chromosomes line up along the center of the cell
Each chromosome attaches to a spindle fiber at its centromere

8. Stage 3: Mitosis Anaphase Centromeres split Chromatids separate
Chromatins move along spindle fibers
Chormatids move to opposite ends of cells.
Cell become stretched and moves apart

9. Stage 2: Mitosis Telophase Chromosomes stretch out
Lose rod like appearance
Occurs at two regions
At either ends of the cell
New nuclear membrane forms around each region of chromosome

10. Stage 3: Cytokinesis Cytokinesis Cytoplasm divides
organelles are distributed to each cell
Cell membrane pinches around the middle of the cell
The cell pinches into to separate cells
Two identical daughter cells are formed

11. Length of Cell Cycle Duration of cell division on the type of cell
Human liver cell
22 hours
Sea urchin cell
2 hours
Human brain
Never divides

12. DNA Replication
Each daughter cell has all genetic information necessary

13. Structure of DNA Double Helix Twisted ladder shape of DNA
2 sides of DNA ladder made of deoxyribose alternate with phophates
Each rung is made of nitrogen bases

14. Nitrogen Bases Molecules containing nitrogen Rungs on the double helix
Four types
A- Adenine
T- Thymine
G- Guanine
C-Cytosine

15. Nitrogen Bases
Bases on one side of the helix match in a specific way to the other side
A matches with T
C matches with G
This pairing is the key to DNA replication

16. Replication Process Two sides of DNA unwind (unzip) and separate
Molecules separate between nitrogen bases
Floating nitrogen bases pair up with corresponding nitrogen base on the DNA
New DNA is produces once nitrogen bases pair up
The two DNA are exact matches
DNA presentation