Assessment Questions

Test and refresh your knowledge with these assessment questions:

1. Outline the phases and stages of the cell cycle.

Answer:

The cell cycle consists of two main phases: interphase and cell division (mitosis). Interphase is in three stages:

  • G1 between mitosis and DNA synthesis, where the cell starts preparation for DNA division.
  • S phase, lasts 10–12 hours and DNA is duplicated during this phase.
  • G2 is between completion of DNA synthesis and the M phase. RNA and other proteins for cell division are synthesised.

Mitosis results in cell division.

2. Differentiate between benign and malignant tumours.

Answer:

  • Benign: Highly differentiated; structure typical of tissue of origin, does not infiltrate normal tissue; slow growth which may stop; harmless except by position, complication, hormones, malignant change.
  • Malignant: Varying degrees of loss of differentiation, i.e. structure atypical; infiltrates surrounding tissue, expands, no capsule; growth erratic, rapid, abnormal mitosis; growth continues; metastases; death by invasiveness and metastases.

3. Identify the different types of adaptive change and the main groups of causes of cell injury.

Answer:

  • Types of adaptive change include: atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia, anaplasia, neoplasia.
  • The main causes of cell injury include: physical agents, electrical forces, chemical injury, biological agents, nutritional imbalances.

4. Describe what is meant by apoptosis and how this differs from necrosis.

Answer:

  • Apoptosis: this is programmed cell death occurring by one of two pathways: extrinsic pathway – extracellular proteins bind to death receptors in cell membrane leading to apoptosi.;
  • Intrinsic pathway – initiated by conditions that impact on mitochondrial membrane.
  • Necrosis: various external stimuli lead to cell death of one of the following two main types:
  • coagulative – tissue remains firm
  • liquefactive – tissue becomes liquid and often contains pus

Patterns of necrosis include: caseous, fat, fibrinoid, gangrenous.

5. What are the main methods of treatment of necrosis?

Answer:

  • Antibiotics: treat associated infections determined by susceptibility to different antibiotics. Caseous necrosis needs treatment for TB mycobacterium.
  • Surgery: abscess drainage, debriding wound, or amputation.
  • Maggot therapy: performing three main functions:
  • debridement: removes dead tissue
  • disinfection: kills bacteria using substances in gut and outside
  • speeding tissue growth: stimulates growth of fibroblasts and endothelial tissue, enhances angiogenesis and oxygenation

6. List four ways an oncogene influences cell growth.

Answer:

i.Over production of growth factors.

ii.Overexpression of growth factor cell receptors such as human epidermal growth factor receptor -2 (HER-2).

iii.Excessive cytoplasmic signalling such as over-activation of the RAS gene causing increased cell proliferation,

iv.Activation of transcription factors which affect genes in the nucleus that stimulate unchecked growth

7. Discuss how a cell becomes malignant.

Answer:

  • Initiation – carcinogens, such as ultra-violet and ionising radiation, certain viruses and chemicals cause mutation of a gene is the first stage Once initiated, cancers continue to undergo changes that enable them to grow excessively and survive.
  • Promotion – proliferation of the mutant cell and the cell’s ability to avoid DNA repair mechanisms and evade apoptosis. This allows the mutation to be passed on to the daughter cells and proliferation to continue unchecked leading to highly evolved tumour cells.
  • Progression – mutant dividing cells begin to exhibit malignant properties. These cells have a growth advantage and proliferate easily with an unstable genetic structure that allows more mutations to occur. The tumour cell has characteristics that are different from the cell of origin, such as the ability to invade surrounding tissue and metastasise.

8. Describe how a cancerous cell metastasises.

Answer:

Cancer cells detach from the basement membrane in the tissue of origin, access the blood and or lymphatic systems and travel to distant sites to colonise in distant tissues. For a cancer cell to become established in distant sites it must acquire oxygen and nutrition and therefore needs a blood supply, a process known as angiogenesis. It also needs to evade the immune destruction.

9.What is epigenetics? 

Answer:

Epigenetics is the external modifications that switches genes on or off so that they are expressed, or silenced. The modifications do not alter DNA sequence but instead they affect how the cell reads the gene.

10.Identify four general symptoms of cancer.

Answer:

  • Pain
  • Cachexia
  • Anaemia
  • Fatigue

11.What diagnostic tests are used to test for cancer?

Answer:

  • Blood tests – these can reveal abnormalities associated with cancer such as anaemia or abnormal blood cells. In blood cancers such as leukaemia the abnormal cell characteristics can be detected through blood samples.
  • Tumour markers – biochemical substances produced by some cancer cells and are found in the blood, urine or spinal fluid. These tumour markers may be enzymes, antigens, antibodies or hormones and can be used alone as an aid to diagnosis for cancer.
  • Tumour tissue biopsy – examine the tissues and cells for abnormalities. Samples of tissue are obtained in a number of ways, including:
  • surgical excision where the entire tumour is removed
  • laparoscopic and endoscopic methods
  • needle biopsy, which involves withdrawing cells and fluid from a palpable tumour
  • exfoliative cytology, where cells shed from the surace are collected for examination, for example a cervical smear test

12. Name three types of carcinogens.

Answer:

  • Tobacco
  • Alcohol
  • UV radiation

13. Discuss the classification of tumours.

Answer:

  • Tumours are classified according to their cellular characteristics and extent of spread; this is known as staging.
  • The international Tumour Nodes Metastasis (TNM) sysytem has been established to standardise the way cancers are classified.
  • T describes the tumour size, N identifies and classifies lymph node involvement and M identifies if there is metastasis and the extent of spread.
  • Helps to provide an indication of prognosis and plan treatment,
  • Helps in evaluating the results of treatment.
  • Facilitates information exchange between centres and contributes to international research.

14.Discuss three types of therapy used in cancer treatment.

Answer:

i. Surgery – effective in the removal of solid tumours with well defined margins that have not spread. The tissue around the tumour is also removed to ensure complete removal of cancerous cells. Ttissue samples to be taken for examination.

ii. Radiation therapy – kill cancer cells and shrink the size of the tumour. Ionising radiation damages the DNA of the cancer cell or can delay cell cycle progression resulting in apoptosis. It is most effective where cells are undergoing mitosis. Radiation is suitable for localised areas of cancerous growth and areas that are difficult to access surgically.

iii.  Chemotherapy is the use of drugs to treat cancer. Chemotherapeutic agents are cytotoxic and act on a specific phase of the cell cycle (cell division). Rapidly dividing cells are more vulnerable to the effects of chemotherapy. Chemotherapeutic agents are not specific to cancerous cells and will therefore damage healthy dividing cells.

15. What are the five most common types of cancer in men and in women worldwide?

Answer:

i.  Lung

ii. Liver

iii. Colorectal

iv. Stomach

v. Breast

16. Identify three screening methods that are used to detect cancer.

Answer:

i.    Breast: mammography

ii.   Cervical: cytology, HPV testing, visual inspection

iii.  Colorectal: faecal occult blood, flexible sigmoidoscopy,colonscopy