Chapter 4 Cell Reproduction Mitosis Mitosis is the

Chapter 4 Cell Reproduction

Mitosis • Mitosis is the process in which the nucleus divides to form two identical nuclei. • Each of the two nuclei contains the same number and type of chromosomes as the original. • The parent cell then undergoes division.

Mitosis

Division of Cells 10: 45

Asexual Reproduction • New organisms are produced from one parent. • Offspring produced from asexual reproduction have DNA that is identical to the DNA of the parent organism

Examples of Asexual Reproduction in Plants

Examples of Asexual Reproduction in Animals Hydra Planaria

Sexual Reproduction and Meiosis • A new organism is produced when sex cells from two parents combine. • The sex cell from the male is the sperm. • The sex cell from the female is the egg. • A human body cell has 46 chromosomes. • Human sex cells have 23 chromosomes.

DNA • The chromosomes in the nucleus of a cell contain a code. This code is in the form of a chemical called deoxyribonucleic acid, or DNA. • DNA controls the activities of cells with coded instructions.

History of DNA • Scientist Rosalind Franklin discovered that the DNA molecule was a strand of molecules in a spiral form. • In 1953, scientists James Watson and Francis Crick made a model of a DNA molecule.

Mutations • Any permanent change in a gene or chromosome of a cell is called a mutation. • Many mutations are harmful to organisms. • Some mutations do not appear to have any effect on the organism.

Mutations

Cloning Video (3: 19)