THE CELL CYCLE Mitosis SEXUAL REPRODUCTION Sexual reproduction

THE CELL CYCLE Mitosis

SEXUAL REPRODUCTION Sexual reproduction leads to genetic variation within a population of organisms. This means that all organisms are not identical.

THE CELL CYCLE - MITOSIS Scientists describe the cell cycle as a process by which a parent cell grows, duplicates itself and divides to produce new cells.

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• INTERPHASE • MITOSIS • CYTOKINESIS

1. INTERPHASE The cell prepares itself for division. A cell’s genetic information directs all of the cells functions and is stored in the form of long molecules of DNA.

1. INTERPHASE Each double-stranded DNA molecule is packaged into a structure called a chromosome.

In preparation for cell division, the chromosomes are duplicated and then condense. Each chromosome is made up of two identical copies of DNA. ANIMAL CELL PLANT CELL

2. MITOSIS DURING MITOSIS THE NUCLEUS DIVIDES MITOSIS HAS FOUR STAGES PROPHASE, METAPHASE, ANAPHASE AND TELOPHASE

STAGE 1: PROPHASE The chromosomes which were duplicated during interphase, condense and shorten.

STAGE 1: PROPHASE The membrane around the nucleus begins to dissolve and disappear.

STAGE 1: PROPHASE The mitotic spindle appears.

PROPHASE

STAGE 2: METAPHASE The doubled chromosomes line up in the middle of the cell on the mitotic spindle.

STAGE 2: METAPHASE The membrane around the nucleus is completely dissolved.

METAPHASE

METAPHASE ANIMAL CELL PLANT CELL

STAGE 3: ANAPHASE The chromosome strands separate and move to opposite ends of the cell.

STAGE 3: ANAPHASE The two sets of chromosomes are identical and have exactly the same genetic information.

ANAPHASE

ANAPHASE ANIMAL CELL PLANT CELL

STAGE 4: TELOPHASE The separated chromosomes arrive at opposite sides of the cell. The mitotic spindle disappears.

STAGE 4: TELOPHASE A new nuclear envelope beings to form around each set of chromosomes, forming two new nuclei.

TELOPHASE

TELOPHASE ANIMAL CELL PLANT CELL

3. CYTOKINESIS In animal and plant cells, the cell membrane pinches in to divide the nuclei, cytoplasm, and organelles to form two daughter cells.

3. CYTOKINESIS After cytokinesis the cells are in interphase and the cell cycle begins again.

CYTOKINESIS

1. INTERPHASE 2. PROPHASE 3. METAPHASE 4. ANAPHA

1. INTERPHASE 3. METAPHASE 2. PROPHASE 4. ANAPHASE

5. TELOPHASE 6. CYTOKINESIS