The Cell Cycle:Interphase, Mitosis and

Cytokinesis

Gridlock Rules

Introduction:

You should be able to:

• Define interphase, mitosis and cytokinesis

• Describe the cell cycle

• Discuss the events and significance of mitosis.

Definitions:• Interphase: the period during the

cell cycle between cell divisions, during which DNA replication and protein synthesis take place.

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Definitions (cont).• Mitosis: is the process by which the

nucleus of a cell is divided into two nuclei, each with the same number and kinds of chromosomes as the parent cell.

• Cytokinesis: is the process by which the cytoplasm divides forming two distinct cells.

Review:• Chromosomes: are

structures in the cell that contain genetic information that is passed from one generation to the next.

Chromosomes:• Only visible during mitosis

• Made up of chromatin (DNA and proteins)

• Cells of every organism have a specific number of chromosomes. (Goldfish=94, Humans=46)

Chromosome Structure• Each chromosome is

made up of two identical chromatids joined at a specific site called the centromere.

The Cell Cycle

Cytokinesis

Interphase

Mitosis

Interphase• Period “in between” cell divisions

• Usually longer than other phases

• Chromosomes are unraveled, the DNA is at work

• 3 main parts of interphase– G1 , S , G2

Interphase (cont.)

• G1- Cell growth and development

• S- DNA replication & Protein Synthesis

• G2- Organelle replication

Interphase

Animal Plant

Mitosis•Prophase

•Metaphase

•Anaphase

•Telophase

Prophase• Longest phase of mitosis • Chromosomes begin to form visible coils• Centrioles move to opposite ends of the cell (no centrioles in

plant cells)• Spindle fibers form• Nucleolus disappears• Nuclear envelope breaks down

Prophase

Animal Plant

Metaphase• Shortest phase of mitosis

• Chromosomes are fully coiled

• Chromosomes line up at the middle of the cell

• Spindle fibers form star-like patterns around the centrioles called asters

Metaphase

Animal Plant

Anaphase• Begins when the sister

chromatids begin to separate

• Chromatids move to opposite ends of the cell

• Anaphase ends when the chromatids stop moving

Anaphase

Animal Plant

Telophase• Chromatids uncoil

• Two nuclear envelopes form

• Spindle fibers disappear

• Nucleoli become visible

• Telophase is the end of mitosis, but not the end of cell division.

Telophase

Animal Plant

Animal Cell MitosisI

T

M

A

P

Plant Cell MitosisI

T

M

A

P

Cytokinesis• Immediately following mitosis

• Cytoplasm divides

• Two separate cells are formed

Cytokinesis

Animal

Cell Cycle Summary• Interphase

• Mitosis: •Prophase•Metaphase•Anaphase•Telophase

• Cytokinesis

Plant Vs. Animal Cellular Division

• Animal Cells have centrioles, Plant cells do not

Plant Vs. Animal Cellular Division

•Animal cells form a cleavage furrow during cytokinesis (cell membrane pinches in the middle)

Plant Vs. Animal Cellular Division

•Plants generate a cell plate at the equator during anaphase.

•Cell plate is filled with cellulose to make a new cell wall.

Animal Cell Plant Cell

Cell PlateCleavage Furrow

Prokaryote Vs. Eukaryote Cell Division

• Prokaryotes divide by process called Binary Fission

• They only have one chromosome called a nucleoid

• Nucleoid is copied and separated during division

Prokaryote Vs. Eukaryote Cell Division

• Binary fission produces 2 identical daughter cells

• Can happen as fast as every 20 minutes.

Nucleoid

• Eukaryotes produces 2 or more chromosomes

• Organelles must be evenly separated into the new cells

• Slower process (Human cells take over 16 hours to divide)

Prokaryote Vs. Eukaryote Cell Division

Cancer• Cancer is the uncontrolled

growth and division of cells

• group of cancer cells is a tumor

• As the tumor grows, it destroys neighboring cells and tissues

Cancer• Two types of tumors

1. Benign- cells grow in a ball, does not invade other cells.

2. Malignant- unorganized growth that can spread to other parts of the body or tissues.

Cancer Cells