3.07Cell cycle and Mitosis

The Cell’s Life Cycle Notes

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Why is cell division important?

• To heal cuts, sores, and wounds.• Grow and Develop!• Even after growth ends cell division is

important to make new cells to replace old cells!

Did you know?Billions of blood cells are replaced daily!

Eukaryotic Life Cycle

1. Interphase

2. Mitosis3. Cytokinesis

InterphaseStage 1

1. InterphaseInter= betweenPhase=stage

a. A cell spends most of its life in the stage.

b. Hereditary material (DNA) and organelles are copied (enough for two cells).

c. The cell prepares to divide into two new cells

Facts:

The cell doubles in size

Interphase

Mitosis (division of the nucleus)stage 2

2. Mitosis*Mitosis is a Greek

word that means “thread”.

*The chromosomes look like threads.

*The chromosomes are now copied and

are called, chromatids.

Facts:a. This stage is when the

chromosomes separate.b. Each cell gets a copy of

each chromosome.***Meaning that every new

cell is identical to the original cell!!!

c. happens in all body cells and in many single celled organisms

d. Two identical nuclei are formed.

Mitosis - four stages of mitosis

Chromosomes

1. Genetic material made up of DNA

2. Found in the nucleus of cells

**Mitosis – Eukaryotic Cells ONLY**

http://www.cellsalive.com/mitosis.htm

CytokinesisStage 3

Cytokinesis

• Cyto=Cell

• Kinesis=Split

a. The cell divides completely and produces two cells that are IDENTICAL to the original cell.

46

46

46

1 cell2 cells

Cytokinesis – two new cells!!!!

Cytokinesis: cell splitting into two

1. In animal cells, cell membrane pinches in to divide the cytoplasm.

2. In plant cells, a cell plate forms to divide the cytoplasm.

Mitosis Animation

http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/main.html

Why is mitosis so important?

1. For growth

2. For repair and replacement of cells

3. Provides a way for the genetic information to be copied and passed on to the new cells.

Binary fission

1. Simple cell division in which one cell splits into two

2. Used by bacteria (prokaryotic cells) for reproduction

3. Cell grows, DNA is copied, DNA and its copy separate, and the cell splits in two

In a nut shell…..1. This is the process by which cells reproduce themselves.

______________

2. How do prokaryotic cells make more cells?___________________

3. What are the 3 stages eukaryotic cells go through to make more cells?

___________,__________,_____________

4. Mitosis is the division of the _____________.

5. A human cell has 46 chromosomes. How many does the cell have after cell division?

____________.6. Upon completion of cell division are the new cells identical

to the parent cell? explain

Meiosis

• Two nuclear divisions produce sex cells (sperm and egg) with exactly half of the chromosomes of the parent cell

• Only happens to make cells for sexual reproduction (Oh my!)

Meiosis Animation

• http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/page3.html

Why is meiosis important?• It makes sexual reproduction possible

• And that results in a new individual that is a unique combination of genes, having a full set of chromosomes for its species, but with half from each parent.

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The significant difference!

• Mitosis• (My toe, sis!)• Makes body cells.

• New cells have the exact same number of chromosomes as the old cell

• Meiosis• (Oh my! myOsis)• Makes sex cells, sperm

and egg• New cells have half of

each set of chromosomes

Review:

• What is the cell cycle?• How are mitosis and meiosis alike? How

are they different?• What process makes new body cells?• What process makes reproductive cells?• How does a bacterium reproduce?• When does cytokinesis occur?• How is cytokinesis different in plant and

animal cells?

Why is meiosis important?

• It makes sexual reproduction possible. P.324• Results in a new individual that has a unique

combination of genes.Pg. 613• Each parent gives exactly one-half of the chromosomes. • Making a full set of chromosomes for its species.

GETncm/justsaycust-recrate-itemcommunittg/stores/dtg/stores/d-favorite-listruejust-say-no

Meiosisi = how i was created!

• Two nuclear divisions

• Produce or make:

1. Sex cells (sperm and egg)

2. The sex cells have half of the chromosomes of the parent cell -23

3. This happens to make cells for sexual reproduction (Oh my!)

• Sex Cell

• Sex Chromosome

• Egg or sperm

• Thread-like chromosome that carries the genes that determine the sex of the offspring.

• XX=girl• XY=boy

Meiosis Animation

• http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/page3.html

Comparison Mitosis and Meiosis

• Mitosis• (My toe, sis!)• Makes body cells.• New cells have the same

number of chromosomes as the original cell. IDENTICAL

• New cells are identical to the original cell

Meaning:• Skin cells make skin cells,

bone cells make bone cells, etc.

• Meiosis• (i was made this way!!)• Makes sex cells.• New cells have half of

the number of chromosomes as the original.

• No two sperm or egg cells are ever exactly alike.

• Offspring or babies will be

unique!

1. What is the cell division that produces body cells that are identical?

2. Name 3 differences between mitosis and meiosis?

3. What cell division makes gametes or sex cells?

4. How does bacteria or prokaryotic cells reproduce?

5. What happens during cytokinesis?