Ch. 8 Cell Cycle

Somatic Cells

• Somatic cells are the only type of cells that do mitosis

• Somatic cells are diploid (2n) twice the chromosomal information

• Somatic cells are cells that are not gametes (sex cells (egg and sperm))– Ex: skin cells, liver cells, and etc.

• Leads to identical cells• At the end of Mitosis it leads to 2 new cells for

Males and Females

Mitosis

• Type of cell division

• It goes through the cell division steps once– Interphase– Prophase– Metaphase– Anaphase– Cytokinesis– Telophase

Mitosis

Gametes

• Gametes are the only cells that go through meiosis

• gametes are haploid (1n) half the chromosomal information

• Gametes (sex cells (egg and sperm)) are everything but somatic cells

• Leads to genetic diversion• At the end of Meiosis it can lead to either

– Males: 4 sperm– Females: 1 egg and 3 polar bodies (they will be

dissolved in the body and reused again)

Meiosis

• Another type of cell division

• It goes through the cell cycle twice– Interphase I Interphase II– Prophase I Prophase II– Metaphase I Metaphase II– Anaphase I Anaphase II– Cytokinesis I Cytokinesis II– Telophase I Telophase II

Meiosis

Cell cycle steps

• Interphase has 2 gap phases and 1 synthesis phase

• G1– Cell grows, carries out basic functions and produces

molecules it needs to build new organelles and other components it needs to divide

– Know as the primary growth stage

• G0– The cell doesn’t replicate or divide– It can or can not be reversed– Know as the resting stage

Cell cycle steps

• S phase– Genetic material is replicated– Damaged DNA is repaired by enzymes– And chromosomes contain 2 attached sister

chromatids– Known as when genetic material is replicated

• G2– Cell prepares to divide– Produces proteins needed for coordinated

movements of chromosomes– DNA winds more tightly to proteins– Signals the end of Interphase

Interphase

Cell cycle steps

• Prophase– Chromosomes shorten and thicken due to DNA

coiling around histones– Chromosomes become dense and visible – Nucleolus disappears– Centromeres move to either pole and the mitotic

spindle fibers begin to form

• Metaphase– When the chromosomes align down the middle of the

cell and spindle fibers attach to the chromosomes

Cell cycle steps

• Anaphase– When the spindle fibers pull apart the chromosomes

and pull to either pole• Cytokinesis

– Division of the cytoplasm– Cleavage furrow is seen only in animal cells– Cell plate is seen only in plant cells

• Telophase– When 2 new daughter cells emerge– Chromosomes condense– Spindle fibers disappear

Cell Cycle steps in plant and animal

p53

• Used to tell cells that are disfigured to apoptosis (kill themselves off)

• p53 is seen at the G1 check. It is used for DNA, and if the DNA is damaged beyond repair then p53 will trigger apoptosis

• p53 is seen also at the G2 check. It is used to make sure DNA, mitotic spindle fibers, and replication is ok if not p53 can be triggered and apoptosis can happen

Work Cited

• http://search.creativecommons.org/?q=replicating%20cells# (background for title slide)