Duplicating Genetic Information The Cell Cycle Cancer and the Cell Cycle Mitosis Meiosis When Cell...

Duplicating Genetic Information

The Cell Cycle

Cancer and the Cell Cycle

Mitosis

Meiosis

When Cell Division is not perfect

Chapter 8Cell Reproduction and Inheritance


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


Chromatin can condense into a chromosome

Centromere

Telomere

Telomere


Humans have 46 chromosomes

Chromosomes are characterized by

length

Position of the centromere

Banding pattern


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

Let’s Try Some!

2n = 8

3n = 15

4n = 8

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)

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

http://www.cancer.org/

Why Mitosis

Growth and Repair

Products are identical copies

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

Duplicating Genetic Information The Cell Cycle Cancer and the Cell Cycle Mitosis Meiosis When Cell...

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