Upload
charla-owens
View
224
Download
0
Tags:
Embed Size (px)
Citation preview
Duplicating Genetic Information
The Cell Cycle
Cancer and the Cell Cycle
Mitosis
Meiosis
When Cell Division is not perfect
Chapter 8Cell Reproduction and Inheritance
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
Duplicating Genetic Information
Chromatin can condense into a chromosome
Centromere
Telomere
Telomere
Duplicating Genetic Information
Humans have 46 chromosomes
Chromosomes are characterized by
length
Position of the centromere
Banding pattern
Duplicating Genetic Information
So humans have 46 chromosomeswith 23 pairs.
You can see stained chromosomes and these can be arranged in pairs.
The picture of arranged chromosomes is called a karyotype.
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
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)
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
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
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
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
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 AnaphaseHomologous chromosomes separate Sister chromatids separate, becoming
Daughter chromosomes
Telophase I Telophase
Daughter cells are haploid Daughter cells are diploid
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 AnaphaseSister chromatids separate, becoming Sister chromatids separate, becomingdaughter chromosomes daughter chromosomes
Telophase I Telophase
4 haploid daughter cells Daughter cells are diploid