• 1. Quiz on Transcription/Translation: you need pen or pencil

• 2. new unit: cell division• 3. based on our newunit, why is this cartoonhilarious?

• Approximately how many cells is an average person made of?

A. You have approximately 100 trillion cells

• How many cells did you start off as?

One SINGLE cell!

SO, how did you come to be so many more cells?

Mitosis!!• How we grow from a single cell (zygote) into approximately 100 trillion cells

Purpose of Mitosis• To separate the copies of DNA (duplicated

chromosomes) from replication into 2 new cells!

New Cells?• Grow or repair tissues• A Healthy adult produces millions of new cells

each SECOND! Some cells divide a lot (skin cell) some cells don’t divide at all (heart cell)

MITOSIS! AKA: Asexual reproduction• Almost every single cell in our body is made from

mitosis– Exceptions: the first cell, sperm/egg cells

• So every cell in our body (minus the exceptions) has IDENTICAL sets of chromosomes (DNA).

Despite very different appearances and functions every cell in your body has the exact same DNA-

because they all came from one original cell dividing

• Differences are due to very complex mechanisms of gene expression that we are only beginning to understand

Control of Mitosis• The steps are usually closely regulated by

“checkpoints”. If something is wrong the cell will kill itself (apoptosis) OR…

• If the damage to the DNA is in the “right” place it can cause the cell cycle to run out of control and the cell is now CANCEROUS.

• Type of cancer depends on the part of DNA that’s wrong AND the location of the cell (ex: lung)

III. Typical Cell Cycle• A. Growth Period of the cell is called

Interphase and accounts for 90% of the cell cycle.• B. Period of cell division during which genetic

information divides is called Mitosis. This accounts for 10% of the cell cycle.

• C. Period of cell division during which the cytoplasm divides is called Cytokinesis

• Interphase is split into 3 stages:

• G1-grow and do it’s thing.

• S- Synthesis- DNA REPLICATION once chromosomes are duplicated there’s no going back!

• G2- “growing” more organelles to prep for mitosis

B. Mitosis (M-Phase): division of genetic material• 10% of the

time (if it even occurs)

• Mitosis has 4 main phases

• For each picture describe 5 things about the chromosomes and/or what they are doing in each phase

Prophase

Metaphase

Telophase

Anaphase

Cytokinesis

• The cell splits into 2

mitosis live video

• http://www.youtube.com/watch?v=aDAw2Zg4IgE

• Each table go to a computer• 1st: controlling the cell cycle• http://goo.gl/Ulwew• 2nd: HW: Mitosis web quest. Becomes HW if

not completed in class!

• Explain why this is “funny”.