Cancer

Question 1

What are tumours?

Answer 1

A mass of abnormal cells that are undergoing uncontrolled cell division.

Question 2

What are benign tumours?

Answer 2

They are non-cancerous cells.

Question 3

What are malignant tumours?

Answer 3

These are cancerous cells.

Question 4

What is the difference between benign and malignant tumours?

Answer 4

1. Benign tumours are non-cancerous and Malignant tumours are cancerous.
2. Benign tumours do not invade surrounding tissues and Malignant tumours do invade surrounding tissues.
3. Benign tumours grow slower compared to Malignant tumours.
4. Benign tumours are often surrounded by connective tissue, so they are easy to remove, and Malignant tumours form their own blood supply, so they are harder to remove.
5. Benign tumours are usually harmless unless they cause a blockage or pressure in the body whereas Malignant tumours can spread through other parts of the body.

Question 5

THE FORMATION OF TUMOURS

Question 6

What is the role of tumour suppressor genes?

Answer 6

They produce proteins that slow down cell division or cause apoptosis.

Question 7

How can a mutation in the tumour suppressor genes lead to the formation of a tumour?

Answer 7

1. A mutation could result in the tumour suppressor gene not being expressed or the proteins produced having an altered amino acid sequence.
2. If there is a non-functional protein the cells will dive by mitosis rapidly and uncontrollably, leading to the formation of a tumour.

Question 8

What is the role of tumour photooncogenes?

Answer 8

They code for proteins which stimulate cell division.

Question 9

How can a mutation in the photooncogenes lead to the formation of a tumour?

Answer 9

1. A mutation in the gene can lead to it being overexpressed and to the overproduction of proteins that stimulate cell division.
2. This means the cells divide by mitosis, rapidly and uncontrollably.

Question 10

OESTROGEN AND AND THE GROWTH OF TUMOURS.

Question 12

What type of cancer is an increase of oestrogen in the body responsible for?

Answer 12

Breast cancer.

Question 13

When and where do oestrogen levels increase in females?

Answer 13

During menopause, the oestrogen produced by the ovaries decreases but the breast cells start to produced more of it.

Question 14

How can oestrogen lead to the growth of tumour cells?

Answer 14

1 Oestrogen binds to the oestrogen receptors and forms an oestrogen-oestrogen complex.
2. The complex then binds to the promoter regions of the DNA and helps RNA polymerase to bind to the DNA.
3. If the target gene that is transcribed is a photooncogene ot will be translated to form proteins that increase cell division I’m cancerous cells.
4. This means the cancerous cells will undergo uncontrolled celld division and the tumour will grow.

Question 15

EPIGENETICS AND CANCER

Question 16

How does the abnormal methylation of tumour suppressor genes lead to the formation of a tumour?

Answer 16

1. The increases methylation of the tumour suppressors gene means that the transcription factors can’t bind to the promoter regions of the DNA. This decreases the transcription of the tumour suppressor gene and means the mRNA is not translated. This then means that the proteins needed to slow down cell division and control apotosis are not produced and the cells divide rapidly and uncontrollably.
2. The decrease in methylation in photooncogenes means more of the transcription factors are able to bind to the promoter regions. This means that the genes are transcribed more and the more mRNA is translated to make proteins that increases cell division. This leads to rapid and uncontrolled cell division.

Question 17

How do some cancer drugs target the epigenome?

Answer 17

1. Some drugs remove the methyl groups from tumour-supressor genes which allows them to be expressed and produce proteins that decrease cell division.
2. Some drugs add methyl groups to photoncogenes which stops them from being expressed and producing proteins that increase cell division.