Chapter 5 The Cell Cycle and Protein Synthesis

Chapter 5 The Cell Cycle and Protein Synthesis

I. Genes & Chromosomes 1. Genes contain the information needed to build cells and cell products. 2. Genes control thousands of traits.

I. Genes & Chromosomes 3. Genes are usually stored in chromosomes. 4. Chromosomes are located in the nucleus. 5. Chromosomes consist of DNA and special proteins.

I. Genes & Chromosomes

Genes • Specific sections of DNA that code for a specific protein

I. Genes & Chromosomes 6. Different living things have various numbers of chromosomes. a) Humans: 46* b) Housefly: 12 c) Onion: 16

I. Genes & Chromosomes 7. Chromosomes occur in pairs a) Humans: 23 pairs* b) Housefly: 6 pairs c) Onion: 8 pairs

I. Genes & Chromosomes 8. Each member of a chromosome pair has the same type of genes.

Diploid Cell A cell that has pairs of chromosomes

II. Cell Division 1. Occurs when one cell (parent cell) divides to produce two new cells (daughter cells)

II. Cell Division 2. Why would a cell want to divide? a) replace cells * cell death * injury b) growth of organism

II. Cell Division 3. The cell cycle contains three stages a) Interphase

3 a) Interphase • • Genes are copied Sister chromatids are formed

3 a) Interphase Picture

II. Cell Division 3. The cell cycle contains three stages a) Interphase b) Mitosis

3 b) Mitosis • The equal distribution of the parent cell’s duplicated genes between the two new daughter cells • Consists of four phases

Phase 1 – Prophase • Nuclear membrane disappears • Chromosomes coil up • Sister chromatids appear Xshaped • Spindle forms

Prophase Picture

Phase 2 – Metaphase • The sister chromatids are lined up at the center of the spindle

Metaphase Picture

Phase 3 – Anaphase • Each pair of sister chromatids separates into two chromosomes • Daughter chromosomes move to opposite ends of the cell

Anaphase Picture

Phase 4 – Telophase • Daughter chromosomes reach ends of spindle and begin to uncoil • New nuclear membranes form, resulting in two new nuclei

Telophase Picture

II. Cell Division 3. The cell cycle contains three stages a) Interphase b) Mitosis c) Cytokinesis

3 c) Cytokinesis • Parent cell divides into two daughter cells • Each cell gets a nucleus, cytoplasm, and some organelles

Cytokinesis Picture

II. Cell Division 4. Each daughter cell has genes identical to those in the parent cell 5. Purpose: replaces dead or worn-out cells

III. Asexual Reproduction 1. Reproduction by mitotic cell division (eukaryotic) 2. Same genetic information as parent cells a) Offspring are identical to parent

III. Asexual Reproduction 3. Examples a)Budding * Seen in yeast * Can result in long chains of cells

III. Asexual Reproduction 3. Examples b) Regeneration * Regrowing missing body parts * Seen in planarian worms

III. Asexual Reproduction 3. Examples c) Spores * Cell surrounded with a protective covering * Produced by mitotic cell division * Each spore can grow into a new organism

IV. Sexual Reproduction 1. Occurs when two org. each give one complete copy of their genes to form a new organism a) Organisms will have 2 genders (male and female)

IV. Sexual Reproduction 2. Uses the process of meiosis a) Involves two cell divisions b) Each daughter cell has just one copy of the genes * Referred to as gametes

Haploid Cell A cell that has only one of each chromosome

2. Meiosis c) Two types of gametes: * Egg produced by females * Sperm produced by males * The sperm and egg each contribute one member of each pair of chromosomes

IV. Sexual Reproduction 3. After meiosis, fertilization occurs a) Combining of gametes

IV. Sexual Reproduction 3. After meiosis, fertilization can occur. a) Egg and sperm unite to form a diploid cell * Referred to as a zygote * Goes through many cycles of mitosis to grow into an adult

V. Offspring 1. Asexual reproduction produces offspring identical to parent 2. Sexual reproduction produces offspring similar to, but different from, the parents