2.8 Disease, Defence and Treatment

Question 1

What is the cell wall of a bacterial cell made of?

Answer 1

Murein (not cellulose)

Question 2

Where is the DNA in a bacterial cell?

Answer 2

It floats loose in the cytoplasm

Question 3

Structure of a virus

Answer 3

Genes in a protein coat

Question 4

Ways in which communicable diseases can be spread

Answer 4

Contact, body fluids, aerosol infection, water, insects, contaminated food

Question 5

What is the causative agent of HIV/AIDS?

Answer 5

The human immunodeficiency virus

Question 6

HIV effect

Answer 6

HIV infects the white blood cells and damages the immune system, so that when other infections take hold They are fatal, as immune system can’t respond.

Question 7

Prevention of HIV/AIDS

Answer 7

Condoms, avoid sharing needles, wearing surgical gloves when treating bleeding

Question 8

Causative agent of chlamydia

Answer 8

Bacterium
Chlamydia trachomatis
Transmitted during unprotected sex

Question 9

Chlamydia effect

Answer 9

Mostly symptomless
causes pain when urinating, unusual discharge, painful testicles, vaginal bleeding
leads to long-term health problems

Question 10

Means of prevention of chlamydia

Answer 10

Using a condom during sexual intercourse

Question 11

Causative agent of malaria

Answer 11

Single celled parasite
Plasmodium
Spread by mosquitoes 🦟

Question 12

Malaria effects

Answer 12

Sweats and chills, vomiting, diarrhoea can be fatal

Question 13

Methods of prevention of malaria

Answer 13

• Use mosquito nets at night
  -use insect repellent lotions
• drain swampy areas where mosquitoes breed
• use insecticide to kill mosquitoes in homes
• Take antimalarial tablets when travelling (only effective for tourists as no long-term immunity)

Question 14

How does the body defend itself against disease

Answer 14

• Intact skin forms a barrier against microorganisms
• Blood clots seal off the entrance to the body while the skin heals
• White blood cells attack invading micro organisms

Question 15

What do phagocytes do?

Answer 15

Ingest microorganisms and digest them

Question 16

What do lymphocytes do

Answer 16

Produce antibodies, which destroy microorganisms
Produce anti-toxins which neutralise poisons produced by pathogens

Question 17

What are antigens?

Answer 17

Pattern of molecules on the surface of all cells

Question 18

Purpose of antigens

Answer 18

All the cells in your body have identical antigens
if a white blood cell encounters a cell with an incorrect pattern of antigens it will attack it

Question 19

The antibody produced depends on

Answer 19

The antigen detected

Question 20

How do memory cells work?

Answer 20

After an antigen has been encountered memory cells remain in the body antibodies are produced very quickly. If the same antigen is encountered again, this memory provides immunity, following an actual infection or vaccination. This response is highly specific as antibodies specific to antigens

Question 21

Factors influencing parents decisions to vaccinate children

Answer 21

Can hurt and scare them
Have side-effects
scare stories (mmr) put them off

Question 22

How do vaccines work?

Answer 22

A vaccine contains antigens derived from a pathogen
It stimulates the lymphocytes produce antibodies to the antigen, building up memory cells so the body becomes immune
Booster injections may be needed to build up enough memory cells

Question 23

What do antibiotics do?

Answer 23

Cure bacterial disease by killing bacteria, or preventing their growth, they do not kill viruses

Question 24

Why is the rate of natural selection increased in bacteria

Answer 24

Extensive use of antibiotics

Question 25

How to prevent infection of MRSA?

Answer 25

Patients entering hospital and screened for MRSA Staff and visitors wash, hands regularly good hygiene in general Stringent hygiene methods are taken with body openings or wounds

Question 26

How to slow natural selection

Answer 26

Doctors avoid prescribing antibiotics wherever possible Doctors vary the type of antibiotic as much as possible as extensive use of a single antibiotic increases risk of resistance

Question 27

Stages in testing of drug treatments - pre-clinical testing

Answer 27

1. Drug tested on human cells, grown in a lab 2. Drug tested on animals monitored for side-effects 3. Clinical trial- Tested and healthy volunteers in low doses 4. More clinical trials to find the optimum dose

Question 28

Clinical testing of drug treatments

Answer 28

Trialled with people with the disease to see if the drug is more or less effective than current treatments

Question 29

Ethical issues of animal testing

Answer 29

Is the need for it superseded by new technologies?

Question 30

Why are monoclonal antibodies called monoclonal antibodies?

Answer 30

They all respond to the same antigen

Question 31

Summary of monoclonal antibodies

Answer 31

Lymphocytes can be cultured in the lab and induced to produce antibodies activated lymphocytes continually divide, producing a very large number of cells. scientists can therefore obtain large quantities of a specific antibody

Question 32

Obtaining monoclonal antibodies steps

Answer 32

1. The antigen the antibody is to be used for is injected into a mouse 2. The mouse’s white blood cells produce the specific antibodies. Many of these white blood cells are found in and collected from the spleen 3. These cells are fused with **myeloma** to form **hybridoma** cells. Myeloma are cancerous cells so they divide continually 4. Hybridoma cells are grown and left over myeloma cells die 5. The antibodies are extracted from the culture medium (the cells) by centrifugation, filtration and chromatography

Question 33

Uses of monoclonal antibodies

Answer 33

**Diagnosis of diseases, e.g. chlamydia, and HIV** Monoclonal antibodies will attacked to specific cells or viruses, thereby detecting the disease by using chemical labels to indicate when it’s attached to a virus. E.g. colour change **Identify different tissue types for transplants** Antibody designed to recognise antigens on a patients cells and detects similar antigens on a potential donor’s **detect malaria** - monitor spread of malaria **supporting chemotherapy for cancers** Monoclonal antibodies specific to cancer cells have a drug attached that will kill them. This makes chemotherapy better targeted.

Question 34

Why do scientists need to continuously create antibiotics

Answer 34

To replace antibiotics that bacteria are resistant to