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

In each of your cells, there is about 2 meters of DNA per nucleus 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

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

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

So humans have 46 chromosomes with 23 pairs. 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.

Duplicating Genetic Information

Duplicating Genetic Information

Duplicating Genetic Information

Duplicating Genetic Information

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

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

The Cell Cycle

Cancer and the Cell Cycle

http://www.cancer.org/ 1- 800 – 4 CANCER 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

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 Prophase I 6. Prophase II Metaphase I 7. Metaphase II Anaphase I 8. Anaphase II Telophase I 9. Telophase II 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 Anaphase Homologous 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 Anaphase Sister chromatids separate, becoming Sister chromatids separate, becoming daughter chromosomes daughter chromosomes Telophase I Telophase 4 haploid daughter cells Daughter cells are diploid