Cell Growth and Division

Chapter 10

Why do cells divide?

• Cells divide to allow the organism to grow and to repair damaged tissue

• Cells grow, then divide. Why don’t they keep growing?

• Large cells do not have enough DNA to function.

• Large cells could not diffuse oxygen and nutrients efficiently. *Agar block lab*

Cell division in Prokaryotes and Eukaryotes:

• Prokaryotes – single chromosome is copied and the cell splits.

• Eukaryotes – All chromosomes must be copied into sister chromatids, held together by a centromere. The copies are then split apart in a process called MITOSIS. The cytoplasm is then split by CYTOKINESIS.

The Cell CycleCell cycle

Main steps of mitosis: “IPMAT”

• Interphase – The cells grows and replicates DNA and centrioles.

• Prophase – DNA wraps up into chromosomes. The nuclear membrane dissolves.

• Metaphase – Chromosomes line up. Spindle fibers created by the centrioles attach to the centromere..

• Anaphase – The will spindle fibers will pull the sister chromatids apart

• Telophase – chromosomes at opposite ends, the nuclear membrane re-forms.

Live video of mitosis:

•Cell division

•Newt cell division

Mitosis Lab Microscope Images

• Onion Root Onion Root tiptip

• Low PowerLow Power

Onion Root tip – High Power

Whitefish blastula – Low Power

Whitefish blastula – High Power

• What What phase phase is this is this cell in?cell in?

Duration of mitosis phases…