biology cell division

1. Duplicating Genetic Information
The Cell Cycle
Cancer and the Cell Cycle
Mitosis
Meiosis
When Cell Division is not perfect
Chapter 8
Cell Reproduction and Inheritance

2. Duplicating Genetic Information
Information about you is in the sequence of
nucleotides in the DNA molecule
In each of your cells, there is about 2 meters of DNA
per nucleus
How does the DNA condense into such as small area?
DNA histones chromatin

3. Duplicating Genetic Information
Chromatin can condense into a chromosome
Centromere
Telomere
Telomere

5. Duplicating Genetic Information
Humans have 46 chromosomes
Chromosomes are characterized by
length
Position of the centromere
Banding pattern

6. Duplicating Genetic Information
So humans have 46 chromosomes
with 23 pairs.
You can see stained chromosomes and
these can be arranged in pairs.
The picture of arranged chromosomes is
called a karyotype.

7. Duplicating Genetic Information

8. Duplicating Genetic Information

9. Duplicating Genetic Information

10. Duplicating Genetic Information

11. Humans
Have 46 Chromosomes
23 pairs
2n = 46
2 is the number of copies of each chromosome
n = the number of different chromosomes
46 is the total number of chromosomes in the
cell

12. Let’s Try Some!
2n = 8
3n = 15
4n = 8

13. The Cell Cycle
The Cell Cycle
Phases include:
1. Interphase – Preparation phases for mitosis
2. Mitosis – Cell division or splitting
Interphase
1. G1 (Growth)
2. S
3. G2 (Growth)

14. The Cell Cycle

15. Cancer and the Cell Cycle

16. Cancer and the Cell Cycle
A cancer cell has unregulated cell growth
Often, the cell cycle checkpoints do not exist.
What is cancer?
Can you catch cancer?
What are the treatments for cancer?
What should I look for?
http://www.cancer.org/
1- 800 – 4 CANCER

17. Why Mitosis
Growth and Repair
Products are identical copies

29. Meiosis – a process that reduces the chromosome
number in such a way that the daughter nuclei only
receive one member of each homologous pair of
chromosomes. Think of it as a double mitotic
division with only a single S phase
Phases of meiosis
1. Prophase I 6. Prophase II
2. Metaphase I 7. Metaphase II
3. Anaphase I 8. Anaphase II
4. Telophase I 9. Telophase II
5. Interkinesis

42. Prophase I
Crossing over of non-sister chromatids
During prophase I, non-sister chromatids can
undergo synapsis, in which the chromatids line up
side-by-side & exchange genetic information
between them
This allows new combination of genetic material
which will become part of a new offspring

47. Prophase I & Metaphase I
Independent assortment
As the chromosomes are pushed around during
prophase I, eventually lining up along the metaphase
plate during metaphase I, their orientation is
different from that of mitosis metaphase
Instead of lining one on top of the other, the
replicated chromosomes line up side by side
according to their homologous characterstics

50. Meiosis I Mitosis
Prophase I Prophase
Pairing of chromosomes No pairing
Metaphase I Metaphase
Homologous chromosomes at Duplicated chromosomes at
Metaphase plate metaphase plate
Anaphase I Anaphase
Homologous chromosomes separate Sister chromatids separate, becoming
Daughter chromosomes
Telophase I Telophase
Daughter cells are haploid Daughter cells are diploid

51. Meiosis II Mitosis
Prophase II Prophase
No pairing of chromosomes No pairing
Metaphase II Metaphase
Haploid # of chromosomes at metaphase Diploid # of duplicated
chromosomes at plate metaphase plate
Anaphase II Anaphase
Sister chromatids separate, becoming Sister chromatids separate, becoming
daughter chromosomes daughter chromosomes
Telophase I Telophase
4 haploid daughter cells Daughter cells are diploid