TOPIC 3: Infection and Response 💉🦠🧫

What is a pathogen?

A micro-organism that causes disease

How do viruses reproduce ?

By inserting genes into cells which causes them to produce more copies e.g measles, AIDS.

What do bacteria do?

Releases toxins that damage your body cells.

How does Rose Black Spot cause disease?

A fungi that causes the leaves to fall off

How does TMV (Tobacco Mosaic Virus) cause disease ?

The discoloured leaves means less chlorophyll which causes stunted growth.

Describe 2 human defence systems to stop disease

• the skin stops the mucus

• The mucus in the nose/trachea traps the bacteria and the acid kills the bacteria

Describe plant defence systems

• Waxy cuticle and bark are physical barriers

• Chemical/poison/ thorns deter other organisms .

Describe one way white blood cells (lymphocytes) kill pathogens

They release anti-toxins which neutralises the toxins the pathogen produce .

Describe another way white blood cells kill pathogens

They produce antibodies which are specific to the antigen of the pathogen, and stick on to the antigen, which causes the virus/pathigen to clump together.

Describe a final way white blood cells kill pathogens

Another white blood cell (phagocytes) will ingest the pathogen , this is called phagocytosis.

How does a vaccine work ?

• A vaccine containing dead/inactive pathogens are inserted into the blood.

• The white blood cells detect the pathogen and are then stimulated to to produce antibodies specific to the antigen

• White blood cells kill pathogens develops memory cells and when re-infected they will produce the correct antibodies quickly

• Pathogen is killed

Why can’t antibiotics kill viruses ?

Because viruses are in the body cells, so it’s difficult to kill the virus without damaging the body cell without causing further damage .

Where did aspirin come from ?

Willow bark

Where does penicillin come from?

A mold

What drugs tested for in clinical trials

• Efficacy

• Dosage

• Toxicity

Describe the stages of drug development

CELL TISSUE → ANIMALS →HUMANS

What is a blind trial?

When two groups are given the drug , but one is given a placebo (fake drug) but neither will know except the doctors.

What is a double-blind trial ?

When neither the doctor or the test participant will know who is given the placebo.

How are monoclonal antibodies produced ?

1. Lymphocytes from mice are combined with a tumour cell to produce a hybridoma

2. Hybridoma multiply producing multiple of the same antibody (identical)

Name three uses of monoclonal antibodies

• Combat disease

• Medical diagnosis

• Detecting pathogens

How do viruses cause disease ?

They invade host cells and use them to make new virus particles. Once the new viruses are made, they cause the cells to burst.