Unit 3- Cell Division: Mitosis

Question 1

What is the function of meiosis?

Answer 1

Creation of gametes

Question 2

How do cells form?

Answer 2

1. When existing cells divide

2. 1 parent cell= 2 daughter cells (identical to parent)

Question 3

What is the cell cycle?

Answer 3

• series of processes that takes place between one cell division and the next

1. Interphase
2. Karyokinesis ( nuclear division)
3. Cytokinesis ( cytoplasmic cleavage)

Question 4

Describe interphase

Answer 4

• cells prepare for mitosis
1. Phase between division
2. Cell spends most time in interphase:
- growth and production of new materials ( synthesizing protein + new organelles)
- replication of DNA
Duplication of chromosomes ( 2 identical chromatids)
- final growth for cell division

Question 5

Describe early prophase

Answer 5

• part of karyokinesis
1. Early
- chromosomes become visible
—threads of chromatin become thicker and shorter

Question 6

Describe late prophase

Answer 6

1. Centrioles separate, move to poles and spindle fibers from between them
2. Nuclear membrane and nucleus break down
3. Chromatids become visible
4. Chromatin network becomes visible as chromosomes: 2 chromatids attached by a centromere

Question 7

What is the function of mitosis?

Answer 7

Create somatic cells

Question 8

Describe metaphase

Answer 8

1. Chromosomes align at equator

2. Spindle fibers attach to their centromeres

Question 9

Describes Anaphase

Answer 9

(Back phase)

1. Spindle fibers contract, pulling apart chromosomes
2. Chromatids move to polar regions of spindle [group at poles]
3. One chromatid of each chromosome moves to opposite poles
4. Now called ‘daughter chromosomes’

Question 10

Describe telophase

Answer 10

1. Identical daughter cells
2. Nuclear membrane reforms
3. Nucleus reforms
4. Cytokinesis occurs

Question 11

Describe cytokinesis

Answer 11

( cytoplasmic cleavage)

1. Division of cytoplasm
2. Occurs at the end of telophase
3. (Animal cell) - constriction of cell membrane around equator
   - constriction continues into parent cell
   - this divides cytoplasm between the 2 nuclei

Question 12

What is the role of mitosis?

Answer 12

1. Growth
   - zygote can grow into multicellular organism
   - body cells have same no. of chromosomes + genetic make-up
2. REPLACE dead cells + REPAIR damaged cells
3. Asexual reproduction- produces new individuals
   Important in biotechnology + genetic engineering: able to generate whole organisms from limited cells

Question 13

What is a centriole?

Answer 13

1. Small organelle
2. 0,4 micrometers long
3. Hollow cylinder —9 long fibrils—each fibril= 3 micro tubules
4. Animal cells= 2 centrioles found in centromere

Question 14

What is the function of the centriole?

Answer 14

1. Grow spindle fibers

- align chromosomes during cell division

Question 15

What are the structures that make up a chromosome?

Describe them in detail

Answer 15

1. CHROMATIDS
   •formed by a series of genes 
   •2 identical strands that from the chromosome 
   —key to precise nuclear division 
2. CENTROMERE
    •region holding chromatids together 
3. GENES
    •block of DNA carrying 1 characteristic of 
     Organism

Question 16

What are homologous chromosomes and what do they do?

Answer 16

1. Pair of chromosomes that carry corresponding genes
   •a body cell 2 chromosomes of genes for a
   Particular characteristic
   —paternal
   —maternal

Question 17

What are the common cancers?

Answer 17

1. Lung
2. Oesophagus
3. Bowl
4. Prostate
5. Breast
6. Cervix
   (LOB Purple BuCks)