Mitosis

Mitosis Definition:• Normal cell division for growth and repair in

which the DNA replicates and each of the 2 new daughter cells produced has a genetically identical copy of the original parent cell’s DNA.

• The 2 new cells will be genetically identical to the ‘parent cell’ that produced them.

When does Mitosis occur?

1) During Growth.

2) Repair of damaged tissues.

3) During Asexual reproduction (reproduction without a mate and without sex cells).

Hydra

A new organism is growingout from the body of theparent organism. This is by Asexual reproduction viaMitosis cell division.

Spider plant reproducing Asexually (by mitosis cell division)

Bacteria reproducing Asexually (this is also called binary fission NOT mitosis cell division)

Mitosis: development

(a) A Human Zygote (b) A Human Embryo

(c) A Human Foetus

mitoticcelldivision

mitoticcelldivision

Mitosis cell division in a growing fertilised egg cell (or Zygote) to develop into an embryo human:

See JA’s pdf with annotated diagrams of stages of Mitosis(or continue for unannotated diags)

Do task in HB sorting Mitosis pictures into correct order.

Also see Cell cycle diags at end of this ppt:

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

• No distinct chromosomes visible• DNA replicates• Proteins and organelles are synthesised

Prophase

• Chromosomes condense and become visible

• Each chromosome consists of two chromatids joined at the centromere

Metaphase

• Nuclear membrane breaks down• Centrioles start to make spindle fibres• Spindle fibres form across the cell• Each chromosome moves to the equator of the

cell and attaches to spindle

by it’s centromere.

Anaphase

• Centromeres split• Sister chromatids separate and move to

opposite poles of the cell

Telophase

• Cytokinesis occurs (division of the cytoplasm)• Nuclear membranes reform• 2 Nuclei form

Cell Cycle: Mitosis

TASK: Annotate your diagram on HB p16: The Cell

Cycle * G1 : Lots of Proteins are synthesised + more organelles are made* S : DNA replication occurs* G2 : Organelles grow and divide, Energy stores increased in cell* M : Mitosis cell division occurs

4 hours

9 hours

10 hours

Mitosis

1 hour

MG2

G1

S

interphase

CANCER AND IT’S TREATMENT

Definition of a Tumour:

Fast uncontrolled growth by mitosis cell division, of a group of abnormal cells.

Most common cancers in the UK:

Lung Cancer.

Bowel Cancer.See next slide for independent work/HW……

• HW do Peach Box Q1 and Green Box Q1,2,3 both from AS textbook p169.

• Then check answers with p251 (section 11.2)

• Complete handbook p15,16 and top of p17 including the application exercise green box on textbook p171 Q1-6, (ref graph fig 3).

• Then check answers on p251.

• Do Exam Q2 from p174 and Exam Q1 from bottom of p175 AS textbook.

Biology TestFirst lesson back after half term break

• The Blood Circulatory System (mass flow)• Blood Vessels• Blood, Plasma, Tissue Fluid & Lymph.• Plant Transport of Water• Leaf Structure and Xerophytic Adaptations.

• Check HW answers from p189 on p252 and check answers from p195 using pp252-253

ANSWERSPictures on HB p15 in correct order:

A, D, C, E, B.

ANSWERS

Missing word answers from HB p16 (ref p170-171 AS textbook)

1. Interphase

2. Nuclear Division or Mitosis (or sometimes Meiosis)

3. Division of the cytoplasm or Cytokinesis (or Cleavage of the cytoplasm).

ANSWERS

From the graph on HB p16:

1. The S phase of Interphase in Mitosis Cell Division.

2. Telophase / Cytokinesis / Cleavage of the cytoplasm.