Mitosis & Chromosomes

Histology SSNSeptember 22, 2004

Presented By:Tresha Edwards & Nadia Goodwin

The Cell Cycle

What is the ploidy of the cell at stage G2?

Cell during Interphase

STAGES OF MITOSIS

Whitefish Mitosis

Key Structures: Nuclear Membrane, Chromosomes, Spindles, Cytoplasmic membrane

I P M

A T

Prophase

• Assembly of mitotic spindle

• Chromosome condensation

Prophase

Prometaphase

• Nuclear envelope breakdown

• Attachment of chromosomes to spindle apparatus

Metaphase

• Alignment of the chromosomes at the metaphase plate

• Rate-limiting step of mitosis!

Metaphase plateKinetochore microtubules

Spindle poles

Anaphase

Anaphase A• Sister chromatids

separate and move towards poles

• Kinetochore microtubules shorten

Anaphase B• Spindle poles move

apart• Cytokinesis begins

Telophase

• Nuclear envelope reassembly

• Chromosome decondensation

• Cytokinesis is completed

Question 1 Put the numbered cells in sequential order.

2

1 3

4

5

Question 2

This structure could be part of the a) Kinetochoreb) Centromerec) Microtubule

Organizing Center (MTOC)

d) Cleavage furrowe) Chromatid

Question 3

What characteristics would you expect to find in the cell at the pointer:

I. Spindle apparatusII. Nuclear envelopeIII. Contractile ringIV. Equatorial plate

a) I and II onlyb) I, II, and IVc) I and IVd) All

Question 4

1

All of the following pertain to the cell labeled 1, EXCEPT:

a) Nuclear envelope has disbursed

b) Mitotic spindle has begun formation

c) Centrosomes have separated

d) DNA has been duplicated