Section 10-1 & 10-2

Learning Target:Know the reasons for why cells

divide.Learning Outcome:

I will know limitations to cell growth and structure of chromosomes.

Cells divide rather than get larger because…….

1. Demands on DNA would be too great.

2. Cell would have trouble moving food and waste across the cell membrane.

Volume increases faster than surface area.

Each organism has a specific number of chromosomes.

During cell division chromatin condenses into chromosomes.

In order for each cell to get the right number the chromosomes have to double

Therefore, since cells can not become too large they need to divide into “daughter cells”

To do this the DNA first copies itself so each daughter cell receives exact copies of the genetic info needed for the cell

Also the ratio of surface area to volume increases which is a very good thing!

Learning Target:Know the phases of mitosis.

Learning Outcome:I will complete the “Mitosis

Flipbook.”

Cell cycle – The series of events that cells go through as they grow and divide.

G1 – Growth phase #1. Cells increase in size and

make new proteins and organelles.

S – Synthesis. Chromosomes are replicated.

G2 – Growth Phase #2 Cell division organelles

are produced. Short phase.

Cell division is made up of 2 parts.1. Mitosis – division of the nucleus.

Divided into 4 phases.2. Cytokinesis – division of the

cytoplasm.

Chromosomes are visible. Centrioles separate Spindle fibers form Nuclear membrane breaks down.

Chromosomes line up in the middle of the cell

Chromosomes are pulled apart/away from each other.

The opposite of prophase occurs. Chromosomes disappear back to chromatin Nuclear membrane reforms Spindle fibers break apart and disappear

Cytokinesis occurs right after Mitosis and is the division of the cytoplasm.