Cell Division Introduction

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Essential Question and State Standard State Standard Genetics 2 Intro. – Cell Division. There are two types that all living things use. You should understand the difference between Mitosis: asexual cell reproduction, normal cell division. Meiosis: formation of male or female gamete cells with half the amount of DNA Key terms: Mitosis, Asexual Reproduction, Sexual Reproduction, Meiosis, Gamete, Daughter Cells

You began life as a single cell, but there are now more cells in your body than stars in the Milky Way Just in the past second, millions of your cells have divided in two

The dance of the chromosomes in a dividing cell is so precise that only one error occurs in 100,000 cell divisions Each sperm or egg produced in your reproductive organs carries one of over 8 million possible combinations of parental chromosomes

In vitro fertilization (IVF) –A sperm and an egg are joined in a petri dish –The embryo is implanted into the mother’s uterus –IVF is one of many reproductive technologies Figure 8.1

Reproduction WHAT CELL REPRODUCTION ACCOMPLISHES –Is the birth of new organisms When do cells need to divide and reproduce?

Cell division is needed for: –Replacement of lost or damaged cells –Cell reproduction and growth –Produces cells with identical DNA as original. What needs to happen before a cell can divide?

Before a parent cell divides, it duplicates its chromosomes – then splits into 2 daughter” cells, genetically identical to parent cell. –46 chromosomes --> 92 --> 2 new cells each with 46 Passing On the Genes from Cell to Cell

Asexual reproduction: single celled organisms use mitosis to produce two new cells with same DNA as original The Reproduction of Organisms Figure 8.2a (a) Amoeba

–Some multicellular organisms can divide into pieces that then grow into new individuals Figure 8.2b (b) Sea star

Sexual reproduction –Meiosis: process by which organisms make cells with half the amount of DNA Sperm and Egg (sex cells or gametes) –Fertilization: combining an egg and a sperm to make a zygote.

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Review Quiz 1.When do cells normally do cell division? 2.What’s the difference between Mitosis and Meiosis? 3.What is a gamete? 4.What does meiosis produce? 5.What is it called when an egg and sperm combine to make a zygote? Key terms: Mitosis, Asexual Reproduction, Sexual Reproduction, Meiosis, Gamete, Daughter Cells