The Cell Cycle

Division of the Cell : All cells come from preexisting cells. 1.Growth and Development 2.Repair (Healing) 3.Reproduction – ( We will talk about this later) Why do cells divide?

Division of the Cell : All cells come from preexisting cells. Growth and Development Humans start off as one single cell, and by the time they are adults, they have over 10 trillion cells!!! This increase in the number of cells also allows for some of those cells to be specialized for various functions. This is important to the survival of many organisms. Why do cells divide?

Division of the Cell : All cells come from preexisting cells. Repair (Healing) Some organism, are able to regenerate lost limbs (such as arms or tails). Humans can repair skin, blood vessels and bones, or replace cells that have died. You have a “new” skin every 28 days! Why do cells divide?

Division of the Cell : All cells come from preexisting cells. PROKARYOTES Have only one circular chromosome Divide by binary fission EUKARYOTES Have a nucleus containing many chromosomes Divide by Mitosis How do cells divide?

Division of the Cell : All cells come from preexisting cells. PROKARYOTESEUKARYOTES How do cells divide? Binary fission in E. ColiMitosis in White Fish

The Cell Cycle: Eukaryotes During the cell cycle, a cell grows, prepares for division, and divides to form two identical daughter cells, each of which then begins the cycle again. The series of events that cells go through as they grow and divide.

Interphase: The longest phase of the cell cycle Has Three Stages 1.G 1 Phase: – Period of cell growth – New proteins & organelles 2.S Phase: – Chromosomes are replicated – DNA synthesis 3.G 2 : The Shortest of the 3 phases – organelles and molecules required for cell division are produced

M Phase: Mitosis and Cytokinesis Mitosis consists of 4 stages 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase Cytokinesis The division of the cytoplasm, occurs at the same time as telophase.