IB Biology

Cell Division

http://www.youtube.com/watch?v=Q6ucKWIIFmg&feature=BFa&list=ULzEgIO9Kq2_Y&lf=mfu_in_order

                                               

               Access excellence

Unravelling a chromosome:

Human Life Cycle

HaploidEgg23

Adult46

HaploidSperm

23

Diploid Zygote

46

fertilisation

Can you draw and label a pie chart for the above data?

Mitosis in Action

http://www.sumanasinc.com/webcontent/animations/content/mitosis.html

http://www.johnkyrk.com/mitosis.html

Stages of Mitosis

1.

Interphase: Just before a cell divides by mitosis the chromatin condenses into chromosomes.

The chromosomes replicate themselves.

The original chromosome and its replicate are called chromatids and they are held together by a centromere.

chromatid

chromosome

centromere

2.

Prophase: Chromatids become visible as they shorten and thicken. The nuclear membrane disappears and spindle fibres are produced.

Metaphase: The chromatids arrange across the middle of the cell (equator). Their centromeres are attached to spindle fibres which are attached to centrioles at each pole.

3.

4.

Anaphase: The spindle fibres shorten and pull the chromatids apart to opposite ends of the cell. One set goes to one pole, the other to the other one.

Telophase: The nuclear membranes form.

The identical sets of chromosomes form groups at either end of the cell and start to uncoil.

5.

The cytoplasm divides and forms two identical (daughter) cells with the same number of chromosomes.

Let´s Act it out!

Summary

http://www.youtube.com/watch?v=7hQ5xXJSmK4

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/