Topic 3: Genes and environment (Cancer)

Question 1

Define phenotype (2 points)

Answer 1

1. the outward appearance of a characteristic or organism,

2. as a result of the genotype and sometimes the environment.

Question 2

Define Tumour (2 points)

Answer 2

1. a mass of unspecialised, abnormally growing cells,

2. which divide more quickly than normal cells.

Question 3

Define metastasis (1 point)

Answer 3

1. the spread of cancer cells to new areas of the body (often by way of the lymph system or bloodstream)

Question 4

Define Malignant Tumour (1 point)

Answer 4

1. a tumour that invades surrounding tissue and metastasises

Question 5

Define benign tumour (1 point)

Answer 5

1. a tumour that stays intact (does not spread/invade other tissues)

Question 6

What are the 2 types of genes that produce proteins

that control the cell cycle?

Answer 6

1. Proto-oncogenes

2. Tumour suppressor genes

Question 7

Name 3 proteins that are important in the cell cycle and what they do

Answer 7

(1) Cyclins and (2) cyclin-dependent kinases (second) drive the cycle forward
3. Tumour suppressor proteins halt the cycle at checkpoints

Question 8

What does the P53 protein do? (1 point)

Answer 8

1. halts the cell cycle at the G1/S checkpoint

Question 9

if p53 gene is expressed and protein is made it prevents DNA replication in ___ phase

Answer 9

S

Question 10

some cancer cells have a mutated p53 gene, therefore p53 is not produced

these cancer cells therefore have _________ cell division (mitosis)

Answer 10

uncontrolled

Question 11

Key Summary: Explain the effects of mutations in proto-oncogenes
(3 steps)

Answer 11

1. When a proto-oncogene is mutated it becomes an oncogene
2. Oncogenes lead to cell cycle being continually active –controls/stops/brakes on the cycle are not working
3. Activated oncogenes can cause those cells designated for apoptosis to survive and proliferate instead.

Question 12

Key Summary: Explain how mutations in tumour suppressor genes/p53 gene affect the cell cycle
(2 steps)

Answer 12

1. Tumour suppressor genes produce proteins (eg.p53) that halt the cell cycle at certain stages
2. Mutations in these genes may inactivate them, meaning controls/stops/brakes on the cycle are not working

Question 13

Key Summary: How does cancer/a tumour arise?

5 steps

Answer 13

1. environmental mutagen eg. UV light, radiation, carcinogen (read Q);
2. mutagen leads to mutations in DNA of tumour suppressor genes/proto-oncogenes (resulting in oncogenes);
3. cell cycle is disrupted/continually active leading to uncontrolled cell division –stops on cell cycle do not work, shorter interphase, faster cell cycle - so no Hayflick limit, cells do not become specialised, so growth cannot be controlled;
4. Lack of apoptosis - rate of cell multiplication by mitosis is greater than the rate of cell death by apoptosis;
5. an abnormal mass of unspecialised cells called a tumour forms, which may invade/invades surrounding tissue;

Question 14

In which tissues is cancer more likely to develop? (1 point)

Why? (2 steps)

Answer 14

1. in tissues with high rates of mitosis eg. lung, colon, bowel and bone marrow
2. Greater number of cell divisions means more opportunities for errors in DNA replication which may lead to mutation in proto-oncogenes or tumour suppressor genes
3. More mutations lead to greater risk of developing cancer

Question 15

Key Summary: How do cancer cells spread to other tissues?

3 steps

Answer 15

1. Some cancer cells break off a tumour
2. Travel to other parts of the body in blood/lymph
3. Causing secondary/metastatic tumours

Question 16

Properties of normal body cells (4 properties)

Answer 16

Normal body cells can:

1. reproduce when and where it’s needed
2. stick together to form tissues in the right place in the body
3. self destruct when they become damaged or too old
4. become specialised (mature)

Question 17

Properties of cancer cells (6 properties)

Answer 17

1. Don’t stop growing and dividing
2. Ignore signals from other cells
3. Don’t stick together – they lose their adhesion molecules
4. Don’t specialise
5. Don’t repair themselves or die (no apoptosis)
6. Have abnormal shapes and sizes

Question 18

Key Summary: What are the uncontrollable risk factors for cancer?
(2 risk factors)

Answer 18

1. genetic predisposition (genotype)

2. age

Question 19

Key Summary: What are the controllable risk factors for cancer?
(8 risk factors)

Answer 19

1. UV light
2. Carcinogens in tar in cigarettes/tobacco (or other carcinogenic chemicals)
3. other forms of ionising radiation eg. nuclear, x-rays
4. asbestos
5. Diet (additives, low antioxidants)
6. Body mass/weight
7. Alcohol intake (excessive alcohol intake)
8. Some viral infections (e.g. HPV - cervical cancer)

Question 20

Cancer is a ____________disease – _____ risk factors contribute to its development (genetic and environmental factors)

The risk factors lead to ________ __ ____ and mutations may lead to cancer.

Answer 20

multifactorial

many

mutations in DNA

Question 21

Explain why the risk of developing cancer increases with age. (3 steps)

Answer 21

1. Every time a cell divides/DNA replicates then mutations can happen
2. Mutations accumulate as we get older
3. Multiple mutations are usually needed to cause cancer

Question 22

Most common cancers occur _____ frequently in close relatives of cancer patients

Answer 22

more

Question 23

Inherited gene mutations have been identified in what cancers? (6 types)

Answer 23

1. bowel
2. ovarian
3. prostate
4. retinal
5. types of leukaemia
6. breast cancer

Question 24

Mutation in the BRCA1 gene which causes _______ cancer

BRCA1 protein _______ DNA

1 BRCA1 allele mutation – __% chance of cancer development

Answer 24

breast

repairs

60

Question 25

__________ in tar cause mutations in DNA in the epithelial cells of alveoli and bronchioles

carcinogens can travel in the bloodstream to other _______

Answer 25

carcinogens

tissues

Question 26

How can cancer from smoking be prevented? (3 ways)

Answer 26

1. stop smoking
2. smoke fewer cigarettes
3. smoke low tar cigarettes

Question 27

What studies show evidence that x-rays and gamma rays are carcinogens? (2 studies)

How can you prevent cancer due to ionising radiation? (2 ways)

Answer 27

(1) Studies of atomic bomb survivors in Japan and (1) people exposed during the Chernobyl nuclear accident

Prevention: (1) limit x-rays, (2) code of practice for people working with radiation

Question 28

UV light causes a mutation in the DNA of ____ cells

tumour may develop from an established ____

if not removed, cancer cells sometimes spread to other parts of the body, this is called __________

Answer 28

skin

mole

metastasis

Question 29

How can you prevent cancer from UV light?

4 ways

Answer 29

1. Use sunscreen
2. use a hat
3. don’t use sunbeds
4. check the skin and moles regularly for unusual changes

Question 30

Asbestos are a group of _______ that occur naturally in the environment as bundles of fibres

exposure may cause mutations in DNA and increase the risk of _____ cancer and other cancer

Answer 30

minerals

lung

Question 31

How can you prevent cancer from Asbestos? (1 way)

Answer 31

1. code of practice for people working with asbestos (wear necessary equipment such as gas masks, suits, gloves etc)

Question 32

if there is a lack of antioxidants to ________ free radicals (formed from smoke, UV light & cellular metabolism),
free radicals ________

free radicals cause ________ in DNA

Answer 32

neutralise

increase

mutations

Question 33

How can you prevent cancer from lack of antioxidants? (1 way)

Answer 33

1. Eat plenty of fruit and vegetables

Question 34

(viral infection for certain cancers)

_____ cancer from hepatitis
_______ cancer from human papilloma virus (HPV)

a virus’s RNA may contain an _______, which it has
picked up from one of its hosts and transfers to the cell it infects

Answer 34

liver

cervical

oncogene

Question 35

List 5 good features of a good cancer study

Answer 35

1. Representative sample
2. Large sample size (numbers of people involved)
3. Accurate measurements/records must be taken
4. Includes a control group for comparison eg. smokers and non-smokers
5. Other factors controlled/considered
   e. g:
   
   • age
   • gender
   • diet
   • profession
   • alcohol consumption

Question 36

Why is a representative sample a good feature of a cancer study? (2 points)

Answer 36

1. Data collected from a range of people (gender, ethnic group, different nationalities),
2. otherwise conclusions may not be able to be generalised to other groups.

Question 37

Why is a large sample size a good feature of a cancer study? (2 points)

Answer 37

1. Makes {data/results} more reliable, so therefore more valid.
2. Anomalies and side effects from drug trials are more likely to show up.

Question 38

Why are accurate measurements/records a good feature of a cancer study? (1 point)

Answer 38

1. To improve validity (ideally quantitative data rather than qualitative data)

Question 39

Why is a control group for comparison a good feature of a cancer study? (2 points)

Answer 39

1. For comparison.

2. Shows that the lifestyle factor is having the effect.

Question 40

Why is a controlled factors a good feature of a cancer study? (1 point)
e.g. age, gender, diet, profession, alcohol consumption

Answer 40

1. For validity

Question 41

What are the 3 main treatments for cancer? Give a short explanation for each of them

Answer 41

1. Surgery - to remove the tumour)
2. chemotherapy - using powerful chemicals to destroy cancer cells)
3. Radiotherapy - using x rays/radiation to destroy cancer cells)

Question 42

How do chemotherapy and radiotherapy treat cancer? (2 steps)

Answer 42

1. They work by causing cells to carry out apoptosis (cell suicide),
2. causing DNA damage which promotes release of p53 and stops cancer cell division.