Cell Division and Growth PMT

Question 1

What is the cell cycle?

Answer 1

• A series of events that take place in a cell involving cell growth, DNA replication and cell division

Question 2

What are the 3 stages of the cell cycle?

Answer 2

Stage 1 - interphase
Stage 2 - mitosis
Stage 3 - cytokinesis

Question 3

What is interphase?

Answer 3

DNA and organelles are copied

Question 4

What does DNA replication involve?

Answer 4

interphase
mitosis
cytokinesis

Question 5

What happens to chromosomes during DNA replication?

Answer 5

The DNA in the ‘arm’ of each chromosome is replicated

Question 6

What is a chromosome?

Answer 6

A linear DNA molecule tightly coiled around proteins.

Question 7

What is mitosis?

Answer 7

Process where a cell divides to produce two identical daughter cells,

Question 8

Why is mitosis important in organisms?

Answer 8

• Asexual reproduction
• Growth
• Repair of damaged cells
• Cell replacement

Question 9

State the four stages of mitosis

Answer 9

• Prophase
• Metaphase
• Anaphase
• Telophase

Question 10

Describe Prophase

Answer 10

• DNA condenses, Chromosomes become visible
• Nuclear membrane disappears

Question 11

Describe metaphase

Answer 11

• Chromosomes lineup along the cell equator

Question 12

Describe anaphase

Answer 12

• Spindle fibres attach to each chromosome
• ‘Arms’ of each chromosome pulled to opposite poles
• Chromatids separate

Question 13

Describe telophase

Answer 13

• Chromosomes uncoil
• New membrane forms around each set of chromosomes

Question 14

What does cytokinesis involve?

Answer 14

• Division of the cell membrane and cytoplasm
• Two genetically identical daughter cells produced

Question 15

What is cancer and how is it formed?

Answer 15

• Non-communicable disease
• Uncontrolled cell division results in the formation of a primary tumour
• Tumour cells break off and spread to other tissues forming secondary tumours

Question 16

What are percentile charts?

Answer 16

• A chart used to monitor growth
• Measurements can be compared to the expected values at a certain age

Question 17

What does the 95th percentile mean?

Answer 17

95% of measurements will be below the value of the 95th percentile

Question 18

What can doctors determine from percentile charts?

Answer 18

• Slower growth than normal
• Faster growth than normal
• Abnormal growth

Question 19

Describe growth in animals

Answer 19

Growth in animals happens by cell division (mitosis) to increase cell number

Question 20

Describe growth in plants

Answer 20

Growth in plants happens by cell division (mitosis), mainly in meristems, followed by cell elongation and differentiation into specialised cells.

Question 21

What are stem cells?

Answer 21

Cells that are unspecialised and capable of differentiating into a range of different cell types

Question 22

What is meant by differentiation?

Answer 22

• The process by which stem cells have become specialised
• Some genes switch on or off, determining cell type

Question 23

Why is cell differentiation important?

Answer 23

It enables the formation of specialised tissues with specific functions

Question 24

What are embryonic stem cells?

Answer 24

Stem cells found in very early embryos that are unspecialised and capable of differentiating into any cell type

Question 25

What is the function of embryonic stem cells?

Answer 25

Enables the growth and development of tissues in human embryos

Question 26

What are adults stem cells?

Answer 26

Stem cells that can differentiate into a limited range of cell types

Question 27

What is the primary function of adult stem cells?

Answer 27

Replacement of dead cells

Question 28

Where are stem cells found in plants?

Answer 28

Meristems

Question 29

Where is meristem tissue found?

Answer 29

In regions of the plant cells are continuously dividing (root tips, shoot tips)

Question 30

What are meristematic stem cells?

Answer 30

Stem cells found in meristems that are unspecialised and capable of differentiating into any cell type during the life of a plant

Question 31

How can stem cells be used in medicine?

Answer 31

- Stem cells can be simulated to differentiate into specific stem cells - Specialised cells transplanted into the patient - Used to treat damage or disease

Question 32

Where can embryonic stem cells be collected from?

Answer 32

- Donor stem cells removed from embryos grown in vitro - Patient’s own stem cells removed from the umbilical cord before birth

Question 33

What are the benefits of using stem cells in medicine?

Answer 33

- Treat damage or diseases - Treat diseases that would otherwise be untreatable - Using scientific research - Growing organs for transplants

Question 34

What are the risks of stem cells use in medicine?

Answer 34

- Transplanted stem cells could cause tumours - Finding suitable stem cell donors is a difficult task - Stem cells may be rejected by the body - Potential side effect - Long-term risks of using stem cells are unknown - Stem cells may become contaminated during preparation and when transplanted transmit infections to the patient

Question 35

What are the ethical issues related to the use of stem cells in medicine?

Answer 35

- The embryos that were used to provide stem cells are destroyed which is seen as unethical and a waste of a potential human life - May lead to the reproductive cloning of humans