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

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? DNAhistoneschromatin

Duplicating Genetic Information Chromatin can condense into a chromosome Centromere 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 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

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 Phases include: 1.Interphase – Preparation phases for mitosis 2.Mitosis – Cell division or splitting Interphase 1.G 1 (Growth) 2.S 3.G 2 (Growth)

The Cell Cycle

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? – 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 1. Prophase I6. Prophase II 2. Metaphase I7. Metaphase II 3. Anaphase I8. Anaphase II 4. Telophase I9. 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 IMitosis Prophase IProphase Pairing of chromosomesNo pairing Metaphase IMetaphase Homologous chromosomes at Duplicated chromosomes at Metaphase platemetaphase plate Anaphase IAnaphase Homologous chromosomes separateSister chromatids separate, becoming Daughter chromosomes Telophase ITelophase Daughter cells are haploidDaughter cells are diploid

Meiosis IIMitosis Prophase IIProphase No pairing of chromosomesNo pairing Metaphase IIMetaphase Haploid # of chromosomes at metaphaseDiploid # of duplicated chromosomes at platemetaphase plate Anaphase IIAnaphase Sister chromatids separate, becoming daughter chromosomes Telophase ITelophase 4 haploid daughter cells Daughter cells are diploid