tumour/cancer

Question 1

Tumour

Answer 1

• a mass of cells as a result of
  uncontrolled cell division
• can be benign or malignant

Question 2

Benign
tumour

Answer 2

• non-cancerous tumour
• grows large but at a slow rate
• produce adhesive and are
  surrounded by a capsule so they
  cannot spread

Question 3

Malignant
tumour

Answer 3

• cancerous tumour
• grows rapidly
• cells may become unspecialised
• can metastasise
• grow projections
• develop own blood supply

Question 4

Cancer

Answer 4

Malignant tumours that form
due to uncontrolled cell division

Question 5

Metastasis

Answer 5

• cancer cells breaking off from the
  tumour
• spreading to form secondary
  tumours in different tissues or
  organs via the blood or lymphatic
  system

Question 6

Oncogene

Answer 6

• An oncogene is a mutated form of a
  proto-oncogene
• Proto-oncogenes normally stimulate
  cell division
• Mutation causes them to become
  permanently activated, leading to
  uncontrolled cell division
  → This can result in the formation of a
  tumour and potentially cancer

Question 7

Tumour
suppressor genes

Answer 7

genes that produce proteins to
slow down cell division and
cause cell death if DNA copying
errors are detected

Question 8

Epigenetics

Answer 8

• the heritable change in gene
  function
• without changing the DNA base
  sequence
• caused by changes in the
  environment
• can inhibit transcription

Question 9

Hypermethylation

Answer 9

• an increased number of methyl
  groups attached to a gene
• hypermethylation of promoter
  regions prevents transcription
• results in cancer if it happens
  to a tumour suppressor gene

Question 10

Methylation
of DNA

Answer 10

• Methyl groups attach to the
  cytosine base of DNA
• condenses the DNA-histone
  complex
• prevents transcriptional factors
  from binding to the promoter
  region on DNA
• inhibits transcription

Question 11

Acetylation of
histones

Answer 11

• Decreased acetylation inhibits
  transcription
• removing acetyl groups makes the
  histones more positive
• this attracts the negative phosphate
  group on DNA
• making it harder for the
  transcriptional factors to bind to
  promotor region on DNA and inhibiting
  transcription

Question 12

How can oestrogen
increase the risk of
breast cancer?

Answer 12

• Oestrogen is a steroid hormone
• it binds to a receptor site on a
  transcriptional factor
• causing a change in shape
• so it can bind to the DNA to initiate
  transcription
• If these include proto-oncogenes,
  they may lead to uncontrolled cell
  division and tumour formation