Unit 8 Gene Mutations - Cancer

Question 1

Outline characteristics of benign tumours

Answer 1

Benign
- Grow very large but at a slow rate and Non- cancerous.
- Often surrounded by a capsule, so they remain compact and can be removed by surgery with a very low chance of recurrence.
- Localised and not life threatening

Question 2

Outline characteristics of malignant tumours

Answer 2

Malignant
- Cancerous and grow large rapidly.
- Metastasis occurs, meaning the tumour breaks off and spreads to other parts of the body.
- Tumour is not encapsulated and instead can grow projections into surrounding tissues and develop its own blood supply.
- Can be life-threatening and recurrence is more likely

Question 3

Describe the possible causes of development of tumours

Answer 3

• Gene mutation in either the tumour suppressor gene and/or oncogene
• Abnormal methylation of tumour suppressor genes and oncogenes
• Increased oestrogen concentration

Question 4

Outline the impact of the oncogenes

Answer 4

• Oncogenes are the mutated version of a proto-oncogene, which creates a protein that stimulates the initiation of DNA replication and mitotic cell division when the body needs new cells.
• Oncogene mutations can result in this process being permanently activated to make cells divide continually.

Question 5

Outline the impact of the tumour supressor genes

Answer 5

• Tumour supressor genes produce proteins to slow down cell division and to cause cell death if DNA copying errors are detected
• Mutation in tumour suppressor genes
• Tumour suppressor genes are not transcribed/expressed as change in amino acid sequence
• Results in uncontrollable cell division;

Question 6

Outline the impact of abnormal methylation

Answer 6

increased number of methyl groups attached to both copies of tumour supressor gene
- Methylation prevents transcription of gene;
- Protein not produced that prevents cell division
- Leading to uncontrolled cell division/ uncontrolled mitosis

Question 7

Outline the impact of increasing oestrogen concentraion

Answer 7

• Oestrogen is produced by the ovaries to regulate the menstrual cycle, but after menopause, this stops.
• Instead, fat cells in breast tissues can produce oestrogen and this has been linked with causing breast cancer in women post-menopause.
• High levels of oestrogen can lead to over activation of Proto-Oncogen forming an Oncogene resulting in the gene being permanently turned on and activates cell division.

Question 8

Outline the use of sequencing

Answer 8

DNA sequencing is the process used to determine the precise
sequence of nucleotides in a length of DNA

Question 9

Outline sequencing projects in simpler organisms

Answer 9

• The genome sequence is known then the proteome can be derived from the genetic code.
• This may have many applications, including the identification of potential antigens for use in vaccine production

Question 10

Outline sequencing projects in complex organisms

Answer 10

• In more complex organisms like humans, the presence of non-coding DNA and of regulatory genes means that knowledge of the genome cannot easily be translated into the proteome.
• Sequencing methods are continuously updated and have become automated.