Y12 MW - Cell Division (Complete)

Question 1

How many chromosomes are found in a bacterial cell?

Answer 1

One - a circular piece of DNA

Question 2

What type of cell division occurs in prokaryotic cells?

Answer 2

Binary fission

Question 3

What is the process of binary fission?

Answer 3

The single, circular DNA molecule and any plasmids undergo DNA replication
Cytokinesis occurs where the parent cell divides into two daughter cells
Two daughter cells are therefore produced, each genetically identical

Question 4

What are the different stages of the cell cycle?

Answer 4

G1, the S phase, G2 (altogether known as interphase) and mitosis

Question 5

What are the three phases of interphase? Describe these

Answer 5

G1 - first growth phase where protein synthesis occurs and the number of organelles and cytoplasm increases
S phase - DNA replication
G2 - Second growth phase where the cytoskeleton of the cell breaks down and the spindle fibres begin to form

Question 6

True or false? Interphase can be observed within a cell

Answer 6

False

Question 7

What is mitosis?

Answer 7

The process of nuclear division where two genetically identical daughter cells are produced from one parent cell

Question 8

What is mitosis required for?

Answer 8

The replacement of cells and repair of tissues

Question 9

What are the stages of mitosis?

Answer 9

Prophase
Metaphase
Anaphase
Telophase

Question 10

What must occur before mitosis?

Answer 10

Interphase

Question 11

What occurs during prophase?

Answer 11

The chromosomes condense onto histones and so are now visible when stained
The nuclear membrane breaks down

Question 12

What occurs during metaphase?

Answer 12

The chromosome line up at the equator of the cell
The spindle fibres reach the chromosomes and attach to the centromere so each sister chromatid is attached to a spindle fibre from an opposite pole

Question 13

What occurs during anaphase?

Answer 13

The sister chromatids separate at the centromere and the centromere splits in two
The spindle fibres begin to shorten, pulling the sister chromatids to opposite poles of the cell

Question 14

What occurs during telophase?

Answer 14

The spindle fibres break down
The nuclear envelope reforms around each set of chromosomes

Question 15

What is the last stage of mitosis?

Answer 15

Cytokinesis where the cytoplasm and cell divides into two, forming two genetically identical daughter cells

Question 16

How do cancers arise?

Answer 16

Uncontrolled mitosis

Question 17

What is a tumour?

Answer 17

An irregular mass of cells

Question 18

What is cancer?

Answer 18

Uncontrolled cell division which causes a malignant tumour

Question 19

What is the difference between malignant and benign?

Answer 19

Malignant - can travel through the body and invade other healthy tissues
Benign - doesn’t spread around the body to other tissues

Question 20

Name some risk factors for cancer

Answer 20

Obesity
Alcohol intake
Age
Genetics
Smoking
Processed food
UV light

Question 21

What is metastasis?

Answer 21

When tumour cells invade other tissues, resulting in secondary cancers forming in the body

Question 22

What does cancer treatment focus on?

Answer 22

Controlling cell division
Destroying tumour cells

Question 23

How do viruses replicate?

Answer 23

The virus attaches to a cell using attachment proteins to bind to the complementary receptor proteins on the surface of the cell
The virus penetrates the cell membrane and injects its nucleic acid (RNA / DNA) into the cell
The viral nucleic acid undergoes semi-conservative replication using the host cell’s cellular machinery such as ribosomes and enzymes
The new viral nucleic acids are packaged into viral particles and are released when the host cell bursts

Question 24

What is the difference between the structure of prokaryotic and eukaryotic DNA

Answer 24

Prokaryotes:
- Shorter DNA
- No histones
- Loop of DNA / RNA
- Circular chromosomes

Eukaryotes:
- Longer DNA
- Condensed into histones
- Linear chromosomes

Question 25

How is the DNA of chloroplasts and mitochondria similar to that of prokaryotic cells?

Answer 25

They have 70S ribosomes
Circular loop of DNA (in the stroma of chloroplasts and the matrix of mitochondria)