Infection and Response

Health

The physical and mental wellbeing, not just the absence of disease

Pathogen

Any microorganism that can produce disease

Bacterial

Unicellular, produces toxins

Virus

Not cells, enters and duplicates - bursting the cell releasing the virus

Protists

Unicellular, transferred by vectors

Fungi

Multicellular or single cellular

Communicable disease

Diseases that can easily spread

How can pathogens spread

Touching, sneezing, coughing, airborne contamination, lack of hygiene, waterborne contamination, sexual contact, sharing needles, vectors, poorly prepared food.

Disease prevention

Hygiene, disinfect, vaccinations, isolations, wearing a mask, destroying vectors

Physica/chemical barriers in the body

Skin, hair/cilia, mucus, stomach acid, tears, saliva.

Measles virus

Highly contagious virus that causes fever and rash through sneezing/coughing, preventable by vaccination.

HIV/AIDS virus

A virus that attacks the immune system, leading to AIDS, primarily transmitted through blood, sexual contact, or from mother to child during childbirth or breastfeeding, preventable by antiretroviral drugs

TMV virus

Tobacco mosaic virus, a plant virus that infects tobacco and other plants, causing mottled or mosaic patterns on leaves through direct contact, preventable by removing the plant and burning the soil

Rose black spot

is a fungal disease affecting roses, characterized by dark purple or black spots on leaves, leading to leaf drop and reduced photosynthesis through water sources and wind. It is managed by removing infected leaves and applying fungicides.

Salmonella

bacteria that can cause food poisoning in humans, leading to symptoms such as diarrhoea, fever, and abdominal cramps, preventable by washing food and antibiotics

Gonorrhoea

a sexually transmitted infection, which can lead to symptoms like painful urination and discharge. It is treatable with antibiotics, but can cause serious health issues if left untreated.

malaria

a disease caused by the bite of infected mosquitoes, leading to symptoms such as fever, chills, and flu-like illness. It can be prevented by using mosquito nets and insecticides.

Asthma

difficulty breathing

Cancer

uncontrolled rapid cell growth

Type 1 diabetes

lack of insulin in the body

Type 2 diabetes

Insulin is ineffective

Coronary heart disease

Blocked arteries

Phagocytosis

The process by phagocytes engulf and digest foreign particles or microorganisms.

Lymphocytes

Produces soluble proteins called antibodies that help target and neutralize pathogens.

antibodies

Enhances phagocytosis (opsonisation), sticks pathogens together (agglutination), releases anti-toxins to neutralise toxins, kills pathogens.

White blood cell adaptations

Irregular shape and is multi-lobed nucleus to squeeze through blood vessels, large surface area to increase changes of phagocytosis.

Bacteria

Most don’t cause infection, multiplies rapidly, antibiotics, made of cells

Virus

Attacks any living thing, uses organism as host, multiplies inside cells, isn’t affected by antibiotics/ isn’t a cell

Vaccination and immunity

Dead or weak pathogens are introduced. This stimulates white blood cell growth. These white blood cells produce correct antibodies. Antibodies information is stored and reproduced rapidly if infection occurs again.

Aspirin

Found in willow and is a painkiller.

Digitalis

Found in foxgloves and is a painkiller.

 Why is it difficult to develop drugs to kill viruses without damaging the body tissue?

A virus is inside and multiplies inside a cell. Meaning it is hidden from antibodies and white blood cells. You can’t kill the virus without killing the cells.

Painkiller

Reduces pain, relieves symptoms, doesn’t tackle the cause of the problem. eg aspirin

Antibiotic

neutralises toxins and kills bacteria.

Antibiotic resistance

Mutation occurs, allowing some bacteria to survive. New mutated bacteria is resistant and this gene gets passed onto offspring of bacteria.

Drug development

Preclinical testing - lab tests using human cells/tissue.

Still preclinical testing - live animal testing for efficacy, toxicity and dosage

Clinical trials - tested on a healthy human first, then with the illness and finally use a double blind trial to avoid placebo effect.

Double blind trial

Doctor and patient are not aware of the pill taken is the actual drug or a placebo.

Peer review

Results of testing and trials are published after scrutiny by peer review.

Placebo effect

A beneficial effect produced by a placebo drug of treatment, which cannot be attributed to the properties of the placebo itself, and must therefore be due to the patient's belief in that treatment. Given as a control.

Making monoclonal antibodies

Inject mice with the antigen targeted to stimulate B lymphocyte cells.

Correct B lymphocytes are extracted from mice, that produce a particular antibody.

A tumour cell is then fused with the B lymphocytes to form a hybridoma.

The hybridoma is then cloned many times and use to produce the correct antibodies.

The monoclonal antibodies are then separated, purified and ready for use.

Hybridoma

A combination of a lymphocyte and cancer cells that have been fused together for certain characteristics called a hybridoma.

Using monoclonal antibodies

Antigens are proteins found on the surface of cells

The monoclonal antibodies produced are specific to one binding site of a specific antigen

Because monoclonal antibodies only target specific antigens on cells they can be used in a number of ways

Explain how a pregnancy kits use monoclonal antibodies

(HCG) is produced when pregnant

Small amounts of this hormone is passed out in the urine

Monoclonal antibodies in the pregnancy text bind with the HCG to produce a colour change (positive result)

Aphids

insects that have a stylet to penetrate the phloem vessel to feed off the plants sugar-rich sap. This prevents the plant from using the products of photosynthesis for respiration. They also act as a vector carrying viruses, bacteria and fungal diseases from one plant to another.

Controlling aphids

Chemical pesticides, killing aphids. Biological pest control, releasing insects like ladybirds that feed on aphids.

Nitrate ions in soil.

Plants use nitrate ions to convert sugar into proteins

The proteins are needed for growth during protein synthesis

Nitrate deficiency will result in lack of proteins, stunting growth

Magnesium ions in soil

Plants use magnesium ions to make chlorophyll used for photosynthesis

Magnesium deficiency will result in the leaves turning yellow since there is no chlorophyll

No glucose made, no respiration, slowing growth due to lack of photosynthesis

Known as chlorosis.

Stunted growth treatment

fertiliser

spots on leaves treatment

fungicides or antifungal treatment

Area of decay or rotting treatment

remove rotting area

malformed stems of leaves treatment

Remove area of the plant

Discoloration treatment

fertiliser

Physical barriers.

On leaves, they have a waxy cuticle which prevents any insects from eating it - Acts as a pathogen barrier

On some species leaves surface, they have small needles (called raphides) that can puncture and cause wounds in animals and insects mouth's when eaten.

Spines/thorns to prevent larger herbivores

Leaf falls - diseased leaves fall from tree to prevent it spreading

The bark on trees contain lignin. - Dead layer of cells that acts as a barrier

Cellulose builds cell walls to strength the plant cell

Guard cells can seal up pores in leaves

Chemical barriers

Antibacterial chemicals are produced

 Some leaves have trichomes on them which can dispense chemical irritants.

Oil released to prevent aphids attaching

Poison is produced to kill attaching oragnism

They attract other insects (like parasitic wasps) using chemicals so they can get rid of the pest.

Some plants can let out a chemical to alert other plants of the same species that there are insects and herbivores nearby.

Other methods

Plants can shoot an electrical charge from the place it had sensed danger and can cause the leaf to pull away and shrink up. This sudden.

Mimicry - some plants mimic unhealthy plants to avoid being eaten or mimic insects

Curling up when touch will dislodge herbivore.