Topic 3: Cell division

Question 1

How do cells form?

Answer 1

Existing cells divide
Two new cells are formed: 1 parent cell and 2 daughter cells

Question 2

What are the 4 main stages of cell cycle?

Answer 2

Growth and reproduction of new materials
Replication of DNA - Duplication of chromosomes
Final growth and prep for cell division
Mitosis and cytokinesis

Question 3

What are the stages of mitosis?

Answer 3

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 4

What is interphase?

Answer 4

The preparation for cell division through 3 stages:
Growth + production of new materials
Replication of DNA and duplication of chromosomes
Final growth and preparation for division

Question 5

What is the function of chromosomes?

Answer 5

Found in nucleus of cell and contains all genetic information that controls all processes in cell

Question 6

What is the definition of centromere?

Answer 6

Holds two chromatids together

Question 7

What is the definition of chromatids?

Answer 7

Identical copies

Question 8

What is the a gene?

Answer 8

Segment of DNA that codes for a specific trait

Question 9

What happens to chromosomes when getting ready to divide?

Answer 9

Cells get ready to divide
Each chromosome copies itself
Each chromosome then consists of 2 identical chromatids joined together by centromere
Chromatin network untangles and individual chromosomes can be seen

Question 10

What is mitosis?

Answer 10

The division of the nucleus, the end of interphase and consists of 4 phases:
- Prophase
- Metaphase
- Anaphase
- Telophase

Question 11

What is prophase?

Answer 11

Early:
- Chromosomes visible in nucleus as threads of chromatin shorten
- Nuclear membran starts to disappear

Late:
- Chromatids become visible
- Held together by centromere
- Centrioles move to opposite ends of cell
- Spindle fibres begin to form
- Nuclear membrane disappears

Question 12

What is anaphase?

Answer 12

Spindle fibres contract
Centromere splits in 2
Pulls chromatids towards opposite ends of cell = poles

Question 13

What is metaphase?

Answer 13

Chromosomes line up in centre of cell on imaginary line = equator
Chromosomes attach to spindle fibres by the centromeres

Question 14

What is anaphase?

Answer 14

Split and move away to opposite poles

Question 15

What is telophase?

Answer 15

Cytokinesis
2 cells identical

Question 16

Whats the difference between the animal cell and plant cell in telophase?

Answer 16

Plant cell:
- No centrioles
- Cell plate forms

Animal cells:
- Centrioles
- No cell plate

Question 17

What is cytokenisis?

Answer 17

Division of cytoplasm
Different in plants and animals
Animal: constricts and pinches off
Plant: cell plate forms, divide daughter cell

Question 18

What is the role of mitosis?

Answer 18

Growth
Damage
Asexual reproduction

Question 19

What is cancer?

Answer 19

Starts in cell
When a cell doesn’t stop undergoing mitosis
Starts dividing = malignant = cannot be removed
No breaking off = benign = can be removed

Question 20

What is a tumour?

Answer 20

Mass that develops when cells divide quickly in uncontrolled ways

Question 21

What is a malignant tumour?

Answer 21

Harmful cancerous tumour

Question 22

What is carcinagen?

Answer 22

Substance that causes cancer

Question 23

What are the causes of cancer?

Answer 23

1. Increasing age
2. Environment:
   
   • Chemicals
   • Radiation
3. Viruses:
   
   • Cervical cancer
   • Liver cancer
4. Inheritance:
   
   • Breast cancer
5. Diet:
   
   • lacking fibre but high in protein and fat
   • Colon cancer

Question 24

What are the treatments of cancer?

Answer 24

1. Prevention:
   
   • Regular checkups
   • Pap smears
   • Colonoscopies
   • Mammograms
2. Surgery:
   
   • Cutting out cancer
3. Radiotherapy:
   
   • X-rays: radiotherapy
   • Chemicals: chemotheraphy