Infection and Response 16/11/2018 16/11/2018 Infection and Response AQA 2016 Biology topic 3

3.1 Communicable Diseases 16/11/2018

Pathogens 16/11/2018 Pathogens are microbes (micro organisms) that can cause diseases. They can enter the body in a number of ways: They can be breathed in through the mouth or nose They can be ingested in water or food They can enter through cuts or bites in the skin (direct contact) …or other natural openings…

Types of Pathogens 16/11/2018 There are a number of types of pathogens, including: Bacteria – small living cells that produce toxins and reproduce very quickly Fungi – they can produce spores and penetrate human skin A virus – it lives and reproduces quickly inside our cells, causing cell damage Protists - eukaryotic cells that can spread through vectors

Examples of Viral Diseases 1 - HIV 16/11/2018 HIV is spread through sexual contact or exchange of _____ ____ (including blood, a danger for drug users sharing ______). It initially causes flu-like _______. Unless successfully controlled by antiretroviral _____, the virus attacks the body’s ______ system. If enough damage is done the body is at risk to other infections or ______. This late stage HIV is known as _____. Words – cancer, needles, bodily fluids, drugs, immune, symptoms, cancer

Examples of Viral Diseases 2 and 3 – Measles and TMV 16/11/2018 Examples of Viral Diseases 2 and 3 – Measles and TMV Words – photosynthesise, fever, pathogen, fatal, sneezes, vaccinated Measles is a viral disease showing symptoms of _____ and a red skin rash. It can be ______ so most children are ______ against it. Measles is spread by inhaling droplets from _____ or coughs. TMV (tobacco mosaic virus) is a widespread plant ________ that causes a “mosaic” discolouration in the leaf, which affects the plant’s ability to ___________.

Examples of Bacterial Diseases 16/11/2018 Salmonella food poisoning is spread through food prepared in _________ conditions. Chickens are vaccinated against salmonella to control its ______. Symptoms of salmonella include fever, _____, vomiting and diarrhoea. Gonorrhoea is a _______ transmitted disease with symptoms including a thick yellow discharge from the ____ or vagina and pain when _____. It is treated with antibiotics and its spread can be controlled through using ________. Words – urinating, condoms, unhygienic, cramps, spread, sexually, penis

Examples of Fungal and Protist Diseases 16/11/2018 Rose black spot is a ______ disease causing black spots to appear on ______, which then turn yellow and drop early, reducing _________. It is spread through wind and _____ and can be treated using ________ and removing the affected leaves. Malaria, a ______ disease causing recurring fever and can be _____. The spread of malaria can be limited by limiting the chances of being bitten by a mosquito (the “vector”), such as by stopping them from ______ or sleeping under a ____. Words – breeding, net, leaves, fungal, protist, photosynthesis, fungicides, rain, fatal

Microbes: our defence against them 16/11/2018 Our bodies have defence mechanisms against invading microbes: The breathing organs have hairs and produce mucus to cover the lining of these organs and trap the pathogens Hairs and mucus in the nose trap particles that could contain pathogens The skin acts as a waterproof barrier The stomach contains hydrochloric acid, which kills bacteria

White blood cells 16/11/2018 If microbes enter our body they need to be neutralised or killed. This is done by white blood cells: White blood cells do 3 things: They eat the microbe (“phagocytosis”) They produce antibodies to neutralise the microbe The produce antitoxins to neutralise the poisons produced by microbes

Producing antibodies You’re going down 16/11/2018 You’re going down Step 1: The white blood cell “sees” the pathogen (microbe) Step 2: The cell produces antibodies to “fit” the pathogen Step 3: The antibodies fit onto the pathogens and cause them to “clump” Step 4: The pathogens are “eaten” by the white blood cells

Vaccinations 16/11/2018 Vaccinations work by injecting a small quantity of dead or inactive pathogen into the body. The body is “tricked” into producing antibodies ready for the real thing. The body then “remembers” the microbe by producing memory cells that “remember” it. No. of cases of TB in Britain Year 140,000 The spread of diseases can be slowed down using national immunisation programs, such as tuberculosis in 1953: 1953 National vaccination starts

Words – viral, immune, diseases, specific, sparingly Antibiotics 16/11/2018 Antibiotics are used to cure bacterial _______ by killing infective bacteria inside the body. Specific bacteria should be treated with ______ antibiotics. There are two main issues with using antibiotics: They don’t do anything to ______ infections Antibiotics should be used _______ as bacteria can grow _______ to them, e.g. the MRSA “superbug”. Words – viral, immune, diseases, specific, sparingly

Using Painkillers 16/11/2018 Painkillers are drugs used to relieve the symptoms of disease but without killing the pathogens, for example: Ibuprofen Paracetamol Aspirin Q. What about viral infections? It is difficult to treat viral infections without damaging the cells the virus has infected.

I (accidentally) discovered penicillin in 1928 Alexander Fleming, 1881-1955 Discovering new drugs 16/11/2018 I (accidentally) discovered penicillin in 1928 Penicillin was discovered from the penicillium mould. Most new drugs are synthesised by chemists in the pharmaceutical industry. However, the starting point is often a chemical extracted from a plant. For example: The heart drug digitalis comes from foxgloves The painkiller aspirin comes from willow.

Researching new medicines 16/11/2018 16/11/2018 Before new drugs can be approved they have to go through three stages. What are the advantages and disadvantages of each stage? 1. Is it toxic? Preclinical tests are done on cells In some of these stages, the drugs are tested for toxicity, efficacy and dose. 2. Is it safe for animals? Animal tests are carried out (still preclinical) 3. Is it safe for humans? Human volunteers are tested on. This happens with low doses at first before finding the optimum dose.

Placebos Clinical trials can be done in different ways: 16/11/2018 16/11/2018 Clinical trials can be done in different ways: 1) Blind trials Patients do not know which drugs they are taking – a real drug or a “placebo” 2) Double blind trial Neither the doctors or the patients know if they are taking the real drug

3.2 Monoclonal antibodies (Biology HT only) 16/11/2018 3.2 Monoclonal antibodies (Biology HT only)

Monoclonal Antibodies 16/11/2018 Monoclonal antibodies are basically “identical antibodies” that can be made to bind to a specific cell or chemical. They are the same because they are made from the same parent cell. Here’s how: Eek! Step 1: Take an animal (e.g. mouse) and inject it with an antigen Step 2: Extract the B-lymphocytes that the mouse makes in reaction to the antigen Step 3: Fuse this lymphocyte with fast- growing tumour cells to make a “hybridoma” (a cell that produces lots of antibodies) Step 4: The hybridoma then divides really quickly (due to it being made from a tumour cell) which gives you lots of identical antibodies called monoclonal antibodies

Uses of Monoclonal Antibodies 16/11/2018 Locating and identifying specific molecules in a cell or tissue by binding them with a fluorescent dye Testing levels of hormones and other chemicals What are monoclonal antibodies used for? Pregnancy testing Treating cancer by targeting specific cancerous cells

Using monoclonal antibodies to fight cancer 16/11/2018 Radiotherapy and chemotherapy have adverse side effects. Monoclonal antibodies are useful as they specific: Step 1: Produce monoclonal antibodies that are specific to a cancer cell antigen Step 2: Inject the antibodies into the blood There they are! Step 3: The antibodies bind to the cancer cells and tag them for attack by white blood cells Step 4: The antibodies can also be attached to a radioactive or toxic substance to deliver it to cancerous cells I’ll get them!

Pros and Cons of Monoclonal Antibodies 16/11/2018 Pros and Cons of Monoclonal Antibodies Monoclonal antibodies Pros Cons Cancer treatment Can still cause side effects such as vomiting, fever and low blood pressure Target specific cells (unlike radiotherapy, which can kill other cells) Currently not as widely used as scientists first hoped Less side effects

3.3 Plant Disease (Biology only) 16/11/2018

Plant Diseases (HT only) 16/11/2018 How do you know if a plant is diseased? 1) Stunted growth 2) Spots on leaves 3) Areas of decay 4) Growths 6) Discoloured or malformed leaves 5) Pests How do you know what to look for? Reference to a gardening manual or website Lab tests Using testing kits that contain monoclonal antibodies

Examples of Plant Diseases 16/11/2018 Rose black spot is a ______ disease causing black spots to appear on ______, which then turn yellow and drop early. It is spread through wind and _____ and can be treated using ________ and removing the affected leaves. TMV (tobacco mosaic virus) is a widespread plant ________ that causes a “mosaic” discolouration in the leaf, which affects the plant’s ability to ___________. Words – fungal, photosynthesise, virus, leaves, rain, fungicides Aphids!!!

Plant Deficiency Symptoms 16/11/2018 Stunted growth – caused by nitrate deficiency (needed for protein synthesis) Chlorosis – caused my magnesium deficiency (needed to make chlorophyll)

How do plants defend themselves? 16/11/2018 Physical defences Tough waxy cuticle on leaves and cell walls made of cellulose Layers of dead cells (i.e. bark) that can fall off Chemical defences Plants can use antibacterial chemicals and poisons to warn off unwanted insects: Back off Yum Mechanical adaptations Thorns or hairs that deter animals Mimicry or curling their leaves when touched