Why Cells Divide

M. L. Hatter

Young Women’s

Preparatory Academy

ENGAGE: Think, Pair, ShareYou are the Doctor

• Review the information on the next slide.

• Write in your journal 2-3 things you would tell your patients and the reasons for your suggestions.

ENGAGE: You’re the Doctor.What would you tell your patients?

Patient # Gender Age Weight Heart Rate

(beats/min)

Blood Pressure

Energy Level

#1 Male 40 210 95 High Low

#2 Male 40 185 70 Normal High

Doctor’s Advice

Patient #2

• Everything is going well.

• Keep doing what you’re doing.

• See you next year.

Patient #1

• Lose weight• Exercise• Prescription for

lowering you blood pressure.

• Need to see you next month.

EXPLORE: What happens when a cell gets too big?

1) Make a sketch of a cell in your journal.

2) Next describe and make another sketch to show what would happen to the cell if it got too big.

Our cell is too big!

• Cell functions slows down.

• Waste products build up.

• DNA overloaded.

WHAT SHOULD

WE DO?

Our Solution: The cell must divide.

• Before a cell can divide, it must first duplicate its DNA!

DNA REPLICATION

DNA Replication Occurs in the S-Phase of the Cell Cycle

Mitosis (Division of the cell nucleus)

CytokinesisThe process by which the cytoplasm divides and one cell becomes two individual cells. The process is different in plants and animals

Animals - cell pinches inward (forms a cleavage furrow).Plants - a new cell wall forms between the two new cells (forms a cell plate).

Key Terms• Chromatin: Uncoiled DNA

• Chromosome: Coiled DNA (DNA with a copy of itself).

• Chromatid: ½ of a chromosome

• Centromere: Connects two chromatids together to make a chromosome.

• Centrioles: Organelles used in cell division to move chromosomes to opposite sides of the cell.

More Key Terms

• Mitosis: Normal cell division

• Meiosis: Special cell division that creates the sperm and eggs.

• Daughter Cell(s): The new cells produced by cell division.

Chromatin(DNA) to Chromosome