Launch1. Do all cells in the body have the

same DNA or different DNA?2. How many chromosomes do all cells

in the body have?3. What does “divide” mean?

Cell Division and Cell Cycle

Question…

What does the title “cell division” make you think about?

NOTES

Cell division

• The process of one cell dividing into two daughter cells is called cell division.

3 Reasons why cells reproduce

• Growth• Repair• Replacement

Think-Pair-Share:

• Name specific examples of when human cells need to make copies of themselves.– Hint: think about growth, repair, and

replacement.

Genetic Material

• DNA: Instructions found in the nucleus• A chromosome is a long string of DNA that

organizes the DNA.

visible

Chromosomes

• For example, humans have 46 chromosomes, but chickens have 78.

Chromosomes

• A house fly has 12 chromosomes and a tomato plant has 24.

Think-Pair-Share

Does more chromosomes mean the organism is more complex?

Video

• http://www.youtube.com/watch?v=lf9rcqifx34&feature=related

The cell cycle

• The cell cycle is the period of time from the beginning of one cell division to the beginning of the next.

• It consists of three stages:1. interphase2. mitosis3. cytokinesis

Which part of the cell cycle takes the longest?

The cell cycle

• Interphase:– the cell grows bigger,

develops, and performs its functions.

– made up of G0, G1, S and G2

The cell cycle

• DNA replication:– the DNA makes a copy

of itself– the chromosomes

double

The cell cycle

• Mitosis:– The nucleus divides

creating two cells, each with an identical set of chromosomes.