Chapter 10 Cell Reproduction

I. Cell Division and Mitosis Why is Cell Division Important? -All Living things start out as 1 cell. -Growth -Replace worn out and damaged cells. -Single celled organisms can reproduce.

The Cell Cycle -Single cells have life cycles just like living organisms. 1. Length of the cycle a) Different cells complete the cell cycle at different rates. 2. Interphase a) It is a time period of growth and development. b) Most of the cell’s life is spent in Interphase.

Mitosis -Mitosis – the process in which the nucleus divides to form two identical nuclei 1. Steps of Mitosis a) Interphase, Prophase, Metaphase, Anaphase, Telophase (IPMAT)

b) chromosomes – structures in the. nucleus that contains hereditary b) chromosomes – structures in the nucleus that contains hereditary material (DNA) -Humans have 46 chromosomes (23 pairs) in every cell. -Chromosomes double in interphase.

Division of the Cytoplasm a) After two nuclei are formed, the cytoplasm separates forming 2 new cells. b) In animal cells the cell membrane pinches itself off in the middle. c) In plant cells a cell plate forms to divide the cell.

Results of Mitosis a) Division of the Nucleus b) Two nuclei that are identical to each other and the original nucleus. c) All cells have the same hereditary materials (DNA).

Asexual Reproduction -Asexual Reproduction – a new organism is produced from only 1 parent organism -The offspring is genetically identical to its parent. -Many plants like potatoes and strawberries reproduce asexually.

1. Budding – a new organism grows from the body of the parent organism a) When the bud becomes large enough it breaks away on its own. b) Ex. Hydra, sponges, yeast 2. Regeneration – the process that uses cell division to regrow body parts a) Ex. Sponges, planaria, sea stars 3. Fission – an organism copies hereditary material and splits. a) Ex. Bacteria Link to Cellsalive.com

II. Sexual Reproduction and Meiosis -Sexual Reproduction – two reproductive cells come together to create a new organism that is genetically unique -Sperm - male reproductive cell -Egg – female reproductive cell -Fertilization – the joining of egg and sperm -Zygote – the cell that forms in fertilization

1. Diploid – when cells have pairs of similar chromosomes a) Body cells like skin, brain, and bone cells are diploid. b) Human body cells have 23 pairs of chromosomes. 2. Haploid – when cells do not have pairs of chromosomes a) They have half the number of a body cell. b) Reproductive cells are haploid. c) Human reproductive cells have 23 chromosomes total.

Meiosis and Reproductive Cells -Meiosis – produces haploid reproductive cells -Two divisions of the nucleus occurs.

1. Summary of meiosis a) Two cells form during Meiosis I b) Both of those cells make 2 cells in Meiosis II. c) Two divisions result in 4 reproductive cells. d) Each of the 4 cells has half the number of chromosomes as the original cell.

III. DNA What is DNA? -DNA – Deoxyribonucleic Acid -It is a chemical that stores hereditary information 1. DNA’s Structure a) Watson and Crick made the first model of DNA

2. A DNA Model a) DNA is in the shape of a double helix. -a twisted ladder or spiral staircase b) The sides of DNA are made up of deoxyribose sugars and phosphate molecules.

c) The rungs of DNA are made up of 4 nitrogen bases. -adenine (A) ↔ thymine (T) -guanine (G) ↔ cytocine (C) d) One nucleotide is made up of 1 base, 1 sugar, and 1 phosphate. -each of your body’s cells contains about eight billion nucleotides

Genes -Gene – a section of DNA on a chromosome that has the instructions for making a specific protein 1. RNA a) RNA – Ribonucleic Acid - it carries message from DNA in the nucleus to the ribosomes to make certain proteins b) like a ladder with its rungs sawed in half

c) Sides are made up of ribose sugar and phosphate molecules d) Rungs are made of 4 nitrogen bases -Guanine (G) ↔ Cytosine (C) -Adenine (A) ↔ Uracil (U) e) Types -mRNA – messenger RNA -tRNA – transfer RNA -rRNA – ribosome RNA

Mutations -Mutation – any permanent change in a DNA sequence of a gene or chromosome -caused by extra or missing chromosome -caused by x-rays, sunlight, and some chemicals

1. Results of a Mutation a) Without correctly coded proteins, an organism can’t grow, repair, or maintain itself b) A mutation can change the trait of an organism. c) A mutation in a reproductive cell can cause offspring to have that mutation. d) Mutations can be harmful, helpful, or have not effect on the organism.