FULL TOPIC: Infection and Response

Where do plants get mineral ions from?

Soil

What happens to plants when they don't get enough mineral ions?

They suffer deficiency symptoms

What are nitrates needed for?

Making proteins -> growth

What are mineral ions containing (as a subheading)?

Nitrates and Magnesium ions

What does a lack of nitrates cause?

Stunted growth

What are magnesium ions needed for?

Making chlorophyll

Why do plants need chlorphyll?

Needed for photosynthesis

What do plants without magnesium ions suffer from?

Chlorosis and have yellow leaves

What are the 6 common signs that a plant has a disease?

• Stunted growth
• Spots on the leaves
• Patches of Decay (rot)
• Abnormal growths
• Malformed stems or leaves
• Discolouration

How do you identify different plant diseases?

• Looking up signs in a gardening manual or website
• Taking the infected plant to a lab, scientists identify the pathogens
• Using testing kits that identify the pathogen using monoclonal antibodies

What are the physical plant defences?

• Waxy cuticle
• Cell Walls
• Layers of dead cells

How do plants use a waxy cuticle (physical) do defend against disease?

Provides a barrier to stop pathogens entering

How do plants use cell walls (physical) do defend against disease?

Form a physical barrier against pathogens that make it past the waxy cuticle

What are cell walls made from?

Cellulose

How do plants use layers of dead cells (physical) do defend against disease?

Dead cells around their stems e.g., bark on trees

What are the chemical plant defences?

• antibacterial chemicals
• poisons

How do plants use an antibacterial chemicals (chemical) do defend against disease?

These kill bacteria e.g., mint and witch hazel

How do plants use poisons (chemical) do defend against disease?

Deter herbivores e.g., tobacco plants, foxgloves, deadly nightshade

What are the mechanical plant defences?

• thorns and hairs
• leaves which droop or curl
• mimicking

How do plants use thorns and hairs (mechanical) do defend against disease?

Stops animals touching and eating them

How do plants use leaves drooping (mechanical) do defend against disease?

Prevent themselves being eaten by knocking infected off themselves and moving away from things

How do plants use mimicking (mechanical) do defend against disease?

e.g., the Passion flower has bright yellow spots on its leaves which look like butterfly eggs. This stops butterflies laying their eggs on there

What are monoclonal antibodies?

Antibodies made to be identical to the parent cell and are immune cells specific to one (different proteins) binding site to target specific cells

What are antibodies produced by?

B-lymphocytes - a type of white blood cell

What are monoclonal antibodies produced from?

Lots of clones of a single white blood cells - all antibodies are identical and will only target one specific protein antigen

How to make monoclonal antibodies

1. Insert antigen into spleen of mouse
2. Lymphocytes produce antibodies
3. B-Lymphocyte is extracted + fused with tumour cell
4. Fusing of lymphocyte and tumour cell = hybridoma
5. Culture hybridoma to multiply for many uses

Hybridoma cell

A cell made by fusing a B-lymphocyte and a cancer cell.

Why do we use hybridoma cells?

• Clonable
  • Production of monoclonal antibodies
  • Antibodies collected and purified

Why are monoclonal antibodies really useful?

They will only bind to this molecule - this means you can use them to target a specific cell or chemical in the body

What are the everyday uses for hybridoma cells?

1. Diagnosis + Treating cancer
2. Pregnancy Tests

How do hybridoma cells help with diagnosis?

• monoclonal antibodies with dye attach to diseased cell will light
• if no disease then no binding

How do hybridoma cells help with treating cancers?

• Cancer cells have antigens on their cell membranes (specific to cancer) called tumour markers
• Lab grown monoclonal antibodies to bind to tumour markers
• Anti cancer drug (radioactive substance, toxic drug, chemical restricting growth and division) attached to monoclonal antibodies
• Antibodies given to patient through drip
• Antibodies target specific cells (cancerous) because they only bind to tumour markers
• DRUG KILLS CANCER CELLS BUT NOT HEALTHY CELLS

How do hybridoma cells help with pregnancy tests?

• Pregnancy = HCG hormone in urine
• In test there are monoclonal antibodies specific to HCG
• The urine moves antibodies to antigens for the control test
• As mobile monoclonal antibodies move to the control the ones binded to the HCG will produce a result dye

What are the advantages of monoclonal antibodies?

• Bind to specific cells (don't harm healthy cells)
• Cheaper long term for diagnosis

What are the disadvantages of monoclonal antibodies?

• Range of side effects (use of mouse)
• Expensive short term for diagnosis
• Difficult to produce

What are the three main stages in drug testing?

1) Preclinical Testing on human cells/tissues
2) Preclinical Testing on live animals
3) Tested on human volunteers in a Clinical Trial

Why can't you use human cells and tissues to test drugs that affect the whole body?

Testing a drug for blood pressure must be done on a whole animal because it has an intact circulatory system

What does the law in Britain about preclinical testing on animals consist of?

Any drug must be tested don two different live mammals

Why do we do preclinical testing on live animals?

To test efficacy, toxicity, and to find the best dodge

Efficacy

Whether the drug works and produces the effect you're looking for

Why don't people like animal testing?

• Cruelty to animals
• Animals are so different from humans that testing on animals is pointless

Why do people like animal testing?

Some people think its the safest way to make sure the drug isn't dangerous before its given to humans

What does testing on human volunteers in a clinical trial consist of?

1. Healthy volunteers - make sure there are no harmful side effects - low dose, gradually increased
2. If the results are good the drugs will be tested on ill people - optimum dose found
3. Patients put into two groups, one given new drug other given a placebo
4. Blind trials
5. Peer review
6. Publication

Placebo

A fake drug used in the testing of medication

Why do doctors give a placebo?

The doctor can see the actual difference the drug makes - allows for the placebo effect

What is a Blind trial?

The patient in the study doesn't know whether they're getting the drug or the placebo.

What is a Double Blind trial?

When neither the patient nor the doctor knows who has been given the placebo until the results have been given

Why do we have double blind trials?

So doctors monitoring the patients and analysing the results aren't subconsciously influenced by their knowledge

Why do Doctors peer review their work when testing drugs?

To prevent false claims

Painkillers

Relieve pain and reduce symptoms

Antibiotics

Drugs that block the growth and reproduction of bacteria

Why is it important to take the right antibiotics?

Different antibiotics kill different types of bacteria

What is the relationship between viruses and antibiotics?

Antibiotics don't kill viruses

Why is it difficult to develop drugs that kill viruses?

Viruses reproduce using your body cells, which make it difficult to develop drugs that destroy the virus without killing the body's cells

How does bacteria become resistant to antibiotics?

Bacteria mutate

What is the problem of having resistant bacteria within an infection?

When you treat an infection, only the non-resistant strains of bacteria will be killed. The individual resistant bacteria will survive and reproduce, and the population of the resistant strain will increase: NATURAL SELECTION

How do you slow down the rate of development of resistant strains?

Doctors avoid over-prescribing antibiotics

Where do drugs come from?

Many come from plants

Aspirin

• Painkiller to lower fever
• Developed from a chemical found in willow

Digitalis

• Treats heart conditions
• Developed from a chemical found in foxgloves

Drugs extracted from microorganisms

Penicillin

How did Alexander Fleming discover penicillin?

Alexander Fleming started growing bacteria to study but he left the lid off one of his culture plates before he went on holiday. When he came back, he saw there was a ring in the jelly where there was no mould and he realised the bacteria there has been killed. He named the substance that killed the bacteria 'penicillin'.

Vaccinations

Injecting small amounts of dead or inactive pathogens into a person's bloodstream. The pathogens carry antigens which triggers the immune system to produce antibodies to attack them.

What happens when live pathogens of the same type appear after being vaccinated?

The white blood cells can rapidly mass-produce antibodies to kill off the pathogens

What are the pros of vaccination?

• Helped control lots of communicable diseases that were once common
• Epidemics can be prevented if a large percentage of the population is vaccinated

What are the cons of vaccination?

• Vaccinations don't always work
• Sometimes have bad reactions to vaccine

What are the features of the body that defend against disease?

1. Skin
2. Hair + Mucus
3. Trachea + Bronchi
4. Hydrochloric acid

How does the skin help defend against disease?

Skin acts as a barrier to pathogens. Secretes antimicrobial substances (kill pathogens)

How does hair and mucus help defend against disease?

Hair and mucus in your nose trap particles that could contain pathogens

How does the trachea and bronchi help defend against disease?

Trachea and bronchi are lined with cilia - hair like structures, which waft the mucus up to the back of the throat where it can be swallowed

How does the stomach help defend against disease?

Produces hydrochloric acid. Kills pathogens that make it that far from the mouth

What happens to pathogens that make it into your body?

Immune system kicks in and destroys them

What is the most important part of the immune system?

White blood cells

Phagocytosis

White blood cells engulfing foreign cells and digests them

What does invading pathogens have on its surface?

Unique molecules - antigens

What will white blood cells produce when they come across a foreign antigen?

Produce proteins called antibodies

What do antibodies do?

Lock onto the invading cells so they can be found and destroyed by other white blood cells

What makes antibodies special?

Antibodies are specific to the type of antigen they are targeting

What happens when a person is infected with the same pathogen again?

The white blood cells will rapidly produce the antibodies to kill it - the person is naturally immune to the pathogen

What are antitoxins?

counteract toxins produced by the invading bacteria

What are the four things we can do to reduce and prevent the spread of disease?

1. Being hygienic
2. Destroying vectors
3. Isolating infected individuals
4. Vaccination

What hygienic measures can prevent/reduce the spread of disease?

Washing hands thoroughly before preparing food or after you've sneezed

How can destroying vectors prevent/reduce the spread of disease?

Prevent the disease from being passed on

How can you destroy vectors to prevent/reduce the spread of disease?

Insecticides or by destroying habitat so they can not breed

How can isolating infected individuals prevent/reduce the spread of disease?

If you isolate someone who has a communicable disease, it prevents them from passing it on to anyone else

How can vaccination infected individuals prevent/reduce the spread of disease?

Vaccinating people and animals against communicable diseases means that they are less likely to develop the infection and then pass it on to someone else

What are the two Bacterial diseases?

Salmonella and gonorrhoea

What does Salmonella cause?

Food poisoning

What symptoms does Salmonella cause?

Fever, stomach cramps, vomiting, and diarrhoea

What are the symptoms of Salmonella caused by?

Toxins that the bacteria produce

How do you contract salmonella?

Eating contaminated food

How do you prevent Salmonella?

Sanitation, vaccinate animals, cook food thoroughly

How is gonorrhoea transmitted?

Sexual contact (STD)

What are the symptoms of gonorrhoea?

Pain when urinating, thick yellow/green discharge

How do you treat gonorrhoea?

Antibiotics (penicillin)

Why has it become trickier to treat gonorrhoea?

Strains of the bacteria have become resistant to penicillin

How do you prevent the spread of gonorrhoea?

Treated with antibiotics and use barrier methods of contraception (condoms)

What is Malaria caused by?

Protists

What are mosquitoes?

Vectors

What are mosquitoes (vectors) involvement in the spread of malaria?

They pick up the malarial protist when they feed on an infected animal. Every time the mosquito feeds on another animal, it infects it by inserting the protist into the animals blood vessel