A special form of cell division Meiosis A special form of cell division

Review Cell- smallest, more basic unit of life Chromosome- It carries all of the information used to help a cell grow and reproduce DNA- genetic material that is found in all living things Nucleus –brain of the cell Mitosis- where one cell divides into two almost identical cells Somatic cells: body cells

DNA genetic material that is found in all living things DNA long list of instructions that give your body its own shape and function

Review

Chromosomes We have 46 chromosomes They have two copies of DNA Half if these chromosomes come from an egg cell, half from a sperm cell The first cell is divided into two separate cells (Mitosis)

Vocabulary word for meiosis

Vocabulary Words Sex cells: sperm cell and egg cells Meiosis: A type of cell reproduction in which sex cells are produced Sex cells: sperm cell and egg cells Males produced sperm cells and a female produces egg cells Gametes: sperm and egg cell

Vocabulary Words Diploid cell: When a cell has two sets of chromosomes 2n because they have 2 sets of chromosomes. Haploid cell: when a cell has only have one set of chromosomes abbreviated as just “n” because they have one set of chromosomes

Reproduction: 2 types Asexual reproduction: one cell divides into two identical ones Sexual reproduction: sperm cell fertilizes egg cell

Asexual Mitosis is one type of asexual reproduction Mitosis is a form of asexual reproduction because offspring have DNA that is identical to their parents. In asexual reproduction there is only one parent Offspring Parent Cell

Sexual Reproduction Sexual reproduction involves the combining of DNA from two separate cells to begin a new organism. Sexual reproduction usually involves two different parents

Homologous chromosome: the similar but nonidentical chromosome pairs an organism receives from its two parents

Meiosis

Meiosis The goal is to make daughter cells with exactly half as many chromosomes as the starting cells Purpose: Reproduction Process that produces haploids cells

What is meiosis? During Meiosis, two nucleus divisions occur Meiosis I Meiosis II

Vocabulary builder

Interphase Before meiosis starts, each chromosome is duplicated Just like in mitosis

Prophase I The membrane surrounding the nucleus disappears, and twin chromosomes become visible

Mitosis and Meiosis They are similar process because new cells are formed from cells that already exist

Why does it mean to reproduce? Turn and talk to your partners

Cell divide twice during meiosis Before meiosis begins, the chromosomes of the parent cells are copied

Metaphase I Pair of twin chromosomes line up in the middle of the cell

Anaphase I Twin chromosomes move to opposite sides of the cell The sister chromatid stay together, chromosome is being pulled apart

Telophase I A membrane forms around each group of twin chromosomes

The membrane surrounding the nucleus disappears, and the twin chromosomes become visible

Twin chromosomes line up in the middle of the cell split, and then each single chromosome moves to opposite side of the cell

A membrane forms around each set of chromosomes

The cell divides in two.