Communicable diseases-preventing and treating disease

Question 1

why is the immune system of a new born baby not mature?

Answer 1

it cannot make antibodies for the first few months

Question 2

how does a new born baby gain immunity naturally?

Answer 2

• antibodies cross from placenta to foetus in uterus
• first milk produced from mother is called colostrum which is high in antibodies. So within a few days at birth, the breast fed baby will have the same level of antibody protection as mother. This is natural passive immunity

Question 3

Give an example of artificial passive immunity

Answer 3

For certain fatal diseases, antibodies are formed in an individual (usually and animal) then injected in the bloodstream of another individual. This can be live saving but temporary.

Question 4

Give an example of artificial active immunity

Answer 4

immune system of the body is stimulated to make its own antibodies to a safe form of antigen (a vaccine), which is injected to the bloodstream.

Question 5

what may vaccines contain?

Answer 5

• killed or inactivated bacteria or viruses
• weakened strains of bacteria or viruses
• toxin molecules that have been altered and detoxified
• isolated antigens extracted from pathogen
• genetically engineered antigens

Question 6

what is an epidemic?

Answer 6

communicable disease spread at a local or national level

Question 7

what is a pandemic?

Answer 7

communicable disease spread rapidly to different countries and continents.

Question 8

What is herd immunity?

Answer 8

when a significant amount of people have been vaccinated this gives protection to those who don’t have immunity, minimal opportunity for an outbreak to occur.

Question 9

why has a vaccination not been developed for malaria?

Answer 9

Plasmodium is very evasive and spends time in erythrocytes so it is protected by self antigens from immune system and within an infected individual its antigens reshuffle.

Question 10

why has a vaccination not been developed for HIV?

Answer 10

It enters macrophages and T helper cells so it has disabled the immune system itself.

Question 11

what are medicines used for?

Answer 11

• treating disease, curing them e.g chemotherapy

- treating symptoms, curing them e.g painkillers

Question 12

what is the source and action of penicillin?

Answer 12

source: commercial extraction originally from mould growing on melons
action: antibiotic-against bacterial disease

Question 13

what is the source and action of docetaxel/paclitaxel?

Answer 13

source: originally from yew trees
action: treatment of breast cancer

Question 14

what is the source and action of aspirin?

Answer 14

source: based on compounds from willow bark
action: painkiller, reduces fever, anti-inflammatory

Question 15

what is the source and action of prialt?

Answer 15

source: derived from venom of cone snail from oceans around Australia
action: new pain killing drug

Question 16

what is the source and action of vancomycin?

Answer 16

source: soil fungus
action: powerful antibiotic

Question 17

what is the source and action of digoxin?

Answer 17

source: foxgloves
action: heart drug used to treat heart failure.

Question 18

why is maintaining biodiversity important when treating disease?

Answer 18

so we don’t lose organisms that give us the key to a life saving drug.

Question 19

what is pharmacogenomics?

Answer 19

personalised medicine- a combination of drugs that work with your individual combination of genetics and disease.

Question 20

what is synthetic biology?

Answer 20

the use of genetic engineering to develop populations of bacteria to produce much needed drugs.

Question 21

what is selective toxicity?

Answer 21

when antibiotics interfere with metabolism of bacteria without affecting the metabolism of human cells.

Question 22

how does an antibiotic work?

Answer 22

because the bacteria has a binding site for the drug and a metabolic pathway that is affected by the drug.

Question 23

how does antibiotic resistance occur?

Answer 23

a mutation occurs causing an antibiotic resistant bacterium. This reproduces and passes down its genes.

Question 24

why has the rate of antibiotic resistance increased?

Answer 24

• oversubscription of antibiotics to people

- farmer that routinely give antibiotics to animals to prevent infection and loss of profit.

Question 25

what are two common example of antibiotic resistant bacteria?

Answer 25

MRSA and C.difficile

Question 26

Describe MRSA

Answer 26

• bacterium carried on nose and skin
• causes boils, abscesses and potentially fatal septicimiea
• was treated with methicillin, a penicillin like antibiotic but strains became methicillin resistant

Question 27

Describe C.difficile

Answer 27

• bacterium in guts

- produces toxins that damage lining of intestines leading to diarrhoea, bleeding and even death

Question 28

how can antibiotic resistant infections be reduced?

Answer 28

• minimising use of antibiotic and making sure the course is fully completed
• good hygiene in hospitals and care homes.
• disinfecting hands
• isolating infected patients

Question 29

explain how cancer cells are targeted and destroyed by immunotherapy?(3 marks)

Answer 29

• amino acid sequence gives complementary shape to antigen
• variable region specific to antigen on cancer cells
• chemotherapeutic agent attached to antibody

Question 30

suggest reasons why vaccine are unethical?

Answer 30

vaccines have side effects

Question 31

Explain how a vaccine leads to long term immunity?(8 marks)

Answer 31

• vaccine contains antigen
• formation of APC cell
• clonal selection of lymphocytes
• clonal expansion by mitosis
• forming plasma cell that release antibodies
• forming memory cells for faster secondary response

Question 32

Describe stages in the development of anti-biotic resistant bacteria?(5 marks)

Answer 32

• bacterial populations show genetic variation
• random mutation occurs causing them to be resistant to antibiotics
• when antibiotics are used inappropriately, the resistant bacteria SURVIVE
• surviving bacteria pass on alleles for resistance to offspring
• next generation are resistant to antibiotics

Question 33

Why are epidemics more likely to occur when a low population is vaccinated?(2marks)

Answer 33

• herd immunity is not achieved

- there is a higher chance of meeting someone infected

Question 34

what is meant by the term vaccine? (1marks)

Answer 34

preparation containing antigens which triggers an immune response

Question 35

why are booster vaccines necessary? (2marks)

Answer 35

to increase the number of memory cells for a faster secondary immune response

Question 36

why is the secondary immune response faster? (3marks)

Answer 36

• clonal expansion of memory cells by mitosis is faster
• memory cell differentiate into plasma cells
• plasma cells produce antibodies against the antigen

Question 37

what is a subunit vaccine?

Answer 37

contains purified antigens from different strands

Question 38

why can vaccines not cause the disease?

Answer 38

-pathogen doesn’t have genetic material so it cannot replicate

Question 39

evaluate herd immunity in the prevention of epidemics? (6marks)

Answer 39

• herd immunity requires large population to be immune
• reduces spread of disease but also depends on how easily that disease is spread
• vaccination may cause side effects
• vaccination may not be effective to all individuals due to genetic differences
• herd immunity protects this who aren’t immunised
• vaccination requires consent

Question 40

some antibiotics decrease the synthesis of the cell wall, how does this lead to bacterium death? (3marks)

Answer 40

• cell wall not synthesised
• due to osmosis
• cell may burst

Question 41

How can antibiotics kill bacteria in three ways?

Answer 41

-preventing cell wall synthesis; inhibit the enzymes responsible for making molecules in the cell walls. The bacteria die from the leakage of contents or lyse from too much water entering
-disrupting the cell membranes; bind to the phospholipids in the bacterial cell membrane to distort the structure and make the membrane too permeable
-Interfering with the protein synthesis; attach to bacterial ribosomes, which then prevents protein synthesis