Infection and Response

Pathogens are

They cause …

Microorganisms that enter the body and cause disease

communicable disease

Bacteria are

small cells which reproduce rapidly inside your body . They make you feel ill by producing toxins that damage cells and tissues

Viruses

reproduce rapidly and live inside cells and replicate themselves until the cell bursts releasing the virus

Protist

single celled Eukaryotes that can cause disease . Some are parasites which live in other organisms carried by vectors

Fungi

can be single celled or made of hyphae which can produce spores to spread and they grow and penetrate human skin an surface of plants causing disease.

How do pathogens spread?

Water- drinking and bathing in dirty water

Air- Pathogens can be carried in the air or in droplets - cough

Direct contact- picked up by touching contaminated surfaces

Measles

virus spread by droplets from infected person. It can develop red skin rash and show signs of a fever,

HIV

Virus spread by sexual contact. It initially causes flu-like symptoms and can lead to AIDS. if immune system badly damaged

controlled with antiretroviral drugs

Rose Black Spot

fungus that can cause blackspots on rose leaves, leading to leaf drop so less photosynthesis so plant grows weakly. spread by water wind, treated with fungicides and burning infected leaves.Ma

Malaria

caused by a protist and carried by mosquitos which feed on infected animals. When the mosquito feeds on a human it infects it by inserting protists into the blood cell

Fever symptoms reduce by stopping mosquito breeding, mosquito nets

Salmonella

bacteria that causes food poisoning, symptoms fever like, vomiting and diarrhea caused by toxins the bacteria produces

prevented poultry given a vaccination

Ghonorhea

sexually transmitted disease caused by bacteria. Symptoms pain urinating thick yellow or green discharge from vagina or penis. Treated with antibiotics, barrior methods(prevention)

How the spread of disease can be reduced/prevented? (4)

Being Hygienic - wash hands

Destroying vectors

Isolating Infected individuals

Vaccination - cant develop the infection and pass it on

BODY DEFENCE SYSTEM

Hair and mucus

traps particles that could contain pathogens

BODY DEFENCE SYSTEM

Skin

acts as a barrier to pathogens and secretes antimicrobial substances

BODY DEFENCE SYSTEM

Trachea and Bronchi

secrete mucus to trap pathogen

lined with cilia- hair like structures which move forward and backward to move mucus

BODY DEFENCE SYSTEM

Stomach

Produces hydrochloric acid that kills pathogens

White blood cells do … (3)

Phagocytosis

Produce antibodies

Produce Antitoxins

Phagocytosis

wbc engulf foreign cells and digest them

Antigen

Unique molecule on the surface of a cell

Antibody production

Antibodies are specific to …

wbc produce proteins (antibodies) when they come across a foreign antigen to lock onto the antigen so i is found and destroyed. Then antibodies are reproduced rapidly to find similar bacteria. Then if the same pathogen comes antibodies reproduce rapidly so the person is immune

Antigens

Antitoxins

neutralise toxins produced by invading bacteria

Vaccinations

protect from future infections

Injecting a small amount of dead or weakened version of pathogen which carry antigens that cause your body to produce antibodies to attack them so if your infected again wbc can produce antibodies quickly

Vaccinations pros and cons

herd immunity?

help control communicable diseases

Can prevent epidemics if a large population vaccinated - herd immunity

don’t always work

can get a bad reaction but very rare

Painkillers

drug relieves pain, don’t tackle thee cause

Antibiotics

different antibiotics kill

Kill bacteria causing the problem without harming body cells

different bacteria

Bacteria can ______ which can cause it to be _______ to an ______. Some Bacteria may be ______ so ______ may only kill the ______ ______ ____.

mutate resistant antibiotic resistant antibiotic non resistant strains

To slow the development of resistant strains (2)

doctors should avoid over prescribing antibiotics

finish the whole course of antibiotics

Drugs come from…

Drugs do ?

Chemicals produced by plants to defend themselves against pathogens and pests.

treat disease or relieve symptoms

Aspirin

drug painkiller to lower fever / willow bark

Digitalis/ penicillin

treat heart condition/ foxgloves/ petri dish mould microorganism

How Drugs are developed?

1) Preclinical testing - drugs tested on human cells and tissues - cant be done with a drug that affects the whole body

2) Then test the drug on live animals to test efficacy- works? and produces correct effect and toxicity- harmful to find best dosage

3) Then tested on human volunteers in a clinical trial to see if there are any harmful side effects. low does then increases.

4)Patients then randomly put into 2 groups, 1 given new drug other placebo-sugar pill so the doctor can see the difference the drug makes

Clinical trials blind - patient dont know double blind patient and doctor dont know so doctor isn’t influenced by their knowledge

5) peer review to prevent false claims

Monoclonal antibodies are a

collection of identical antibodies produced from one clone

Monoclonal antibodies production

1. An antigen is injected into a mouse

2. The mouse produces lymphocytes, which produce antibodies specific to the antigen

3. Spleen cells which produce the lymphocytes are removed

4. These cells are fused with tumour cells to form hybridoma cells which divide rapidly

5. These hybridoma cells divide and produce lots of monoclonal antibodies specific to the original antigen.

Uses of Monoclonal antibodies

Pregnancy tests - hormone HCG found in urine is detected by antibodies on the test strip.

If pregnant hormone binds to antibodies and moves up the stick carrying hormone and beads so the beads get stuck on the strip turning it blue

How can monoclonal antibodies be used to treat disease?

Monoclonal antibodies target tumour markers/antigens. An anti-cancer drug is attached, which binds specifically to the tumour, killing cancer cells while sparing healthy cells.

In research to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye

Adv and disadv of Monoclonal antibodies

many purposes side effects fever vomiting low blood pressure

Mineral ions that plants need

Nitrates - to make proteins for growth

Magnesium- to make chlorophyll for photosynthesis/ without plants suffer from chlorosis and have yellow leaves

Signs of Plant disease

Stunted growth spots patches of decay abnormal growth malformed stems or leaves discolouration

How to identify the specific plant disease?

look up signs in a gardening manual or a gardening website

Take infected plant to laboratory for scientists to identify the pathogen

use a monoclonal antibody testing kit to identify pathogen

Physical Defences

waxy cuticle barrier to stop pathogens

cellulose cell wall barrier

layer of dead cells around stems

Chemical Defences

produce antibacterial chemicals which kill bacteria

poisons that deter herbivores

Mechanical Defences

Thorns hairs stop animals touching and eating

Leaves that droop or curl when something touches them to prevent them from being eaten or knock off insect

Mimic other organisms