CELL REPRODUCTION THE CELL CYCLE AND MITOSIS

Lesson Objectives—Cell Cycle Describe the properties of cell division in prokaryotes. Describe cell division in eukaryotes. Explain the main differences between cell division in prokaryotic and eukaryotic cells. Describe the basic properties of chromosomes. Describe the key steps in the cell cycle. Identify and describe the main processes in mitosis. Describe how the cell cycle is controlled and define cancer.

Functions of Cell Division 20 µm 100 µm 200 µm (a) Reproduction. An amoeba, a single-celled eukaryote, is dividing into two cells. Each new cell will be an individual organism (LM). (b) Growth and development. This micrograph shows a sand dollar embryo shortly after the fertilized egg divided, forming two cells (LM). (c) Tissue renewal. These dividing bone marrow cells (arrow) will give rise to new blood cells (LM).

CELL REPRODUCTION Cell Division: process by which a cell divides to form two new cells (daughter cells) Three types of cell division, or cell reproduction Prokaryotes (bacteria) Binary fission divides forming two new identical cells Eukaryotes Mitosis Cell or organism growth Replacement or repair of damaged cells Meiosis formation of sex cells, or gametes

EUKARYOTIC CELL DIVISION DNA found on chromosomes located in nucleus of cell Cell cycle continuous process Cells grow DNA replicated Organelles duplicated Divide to form daughter cells 2 Main steps: 1: Mitosis (4 steps—Prophase, Metaphase, Anaphase, Telophase) Nucleus divides 2: Cytokinesis—Cytoplasm divide, forming 2 cells Each new daughter cell is genetically identical to parent cell

Mitosis = nuclear division Mitosis is followed by cytokinesis (cell division) The steps of mitosis ensure that each new cell has the exact same number of chromosomes as the original

Structure of Chromosomes Chromosomes are composed of a complex of DNA and protein called chromatin that condenses during cell division

MITOSIS Process that divides cell nucleus to produce two new nuclei each with a complete set of chromosomes Continuous process Four phases (PMAT) Prophase Metaphase Anaphase Telophase

PMAT (1)Prophase (2)Metaphase (3)Anaphase (4)Telophase Interphase 1 2 Cytokinesis

1. chromosomes visible (sister chromatids) 2. centrioles migrate to the poles (only in animals) 3. nuclear membrane disappears 4. spindle forms

chromosomes line up on the equator of the cell spindles attach to centromeres Equator

sister chromatids separate centromeres divide sister chromatids move to opposite poles

1. chromosomes uncoil • now chromatin 2. nuclear membranes reform 3. spindle disappears

Occurs at end of Mitosis --division of the cytoplasm to form 2 new daughter cells --organelles are divided -Daughter cells are genetically identical Cells return to interphase

Mitotic Division of an Animal Cell INTERPHASE PROPHASE Centrosomes (with centriole pairs) Chromatin (duplicated) Centromere

Mitotic Division of an Animal Cell METAPHASE ANAPHASE TELOPHASE AND CYTOKINESIS Nuclear envelope forming Daughter chromosomes

Name the phases starting at the top. Mitosis Name the phases starting at the top.

2.Name the phase 3.Identify X 4.Identify Y

5. Name the phase

6. Name the phase