6.3 - Defense Against Infectious disease

Question 1

Bacterial

Answer 1

• prokaryotic (no real nucleus)
• divides through binary fission

examples:
- ear and eye infection
- food poisoning - salmonella

Question 2

viruses

Answer 2

• acellular
• have dna and rna
• can not carry out the functions of life without a host
• mutate, evolve, and recombine very quickluy

examples:
- flu , covid, smallpox, HIV

Question 3

Fungi

Answer 3

• eukaryotic, reproduce with spores
• can cause allergic reactions/ respitory issues

examples:
- athletes foot, ringworm

Question 4

protozoa

Answer 4

• simple parasites

example: malaria

Question 5

1st line of defense:
2nd line
3rd line

Answer 5

skin, mucous membranes, pH, lysosomes
phagocytes
lymphocytes : b-t cells

Question 6

Blood clotting

Answer 6

• a cut in the skin causes potential for a pathogen to enter blood.
• Platelets (small cell fragments) and damaged tissue release clotting factors in response to a wound.
• blood clotting factors go through a series of events but end with fibrin fibres forming a mesh around the wound
• plateletes and blood cells get caught in the mesh and form a blood clot. When exposed to air, the blood clot becomes a scab.
• The scab prevents the loss of blood as well the entrance of pathogens.

prothrombine > thrombin> fibrinogen > fibrin.

Question 7

Atherosclerosis

Answer 7

Atherosclerosis is a degenerative disease which causes damage to coronary arteries.

• Macrophages release growth factors. These cause the growth of fibrous tissue.
• Cholesterol builds up in infected areas forming plaque and decreasing the elasticity of arteries.
• A build up of plaque causes lumin to narrow, restricting blood flow.
• If the plaque breaks, blood clotting is triggered
• blood clotting is known as coronary thrombosis

Question 8

Coronary heart disease

Answer 8

• when blood clots occur in the myocardial tissue, it is called coronary heart disease.
• Heart attacks are caused when blood clots completely block coronary arteries
• heart bypass surgery can unblock arteries
• coronary muscle tissue with restricted blood/oxygen flow die.

factors that cause it:

gender: men are more likely to get it
age: elasticity of arteries decreases as you age
genetics: some people are predisposed to high blood pressure/ high cholesterol
smoking: increase blood pressure, constricts blood vessels
bad exercise: lack of circulation
diet: build up of cholesterol

Question 9

Phagocytes - how they work:

Non-specific immunity!

Answer 9

phagocytes track foreign material through their chemo taxis:

• phospholipids released by damaged cells
• proteins released by pathogens
• they attach to the cell surface proteins of the pathogen and engulf it through endocytosis. The fluidity of the plasma membrane allows this to happen.
• a phagosome forms - vesicle that contains the pathogen
• Phagocytes also contain lysosomes
• Lysosomes bind to the vesicle and release enzymes which breakdown and digest the foreign material.
• the waste is expelled through exocytosis.

Question 10

antigen

Answer 10

proteins on the surface of cells and viruses that cause the production of antibodies

Question 11

antibodies

Answer 11

globular proteins which bind to specific antigens and aid the immune process

Question 12

clonal selection.

Answer 12

there are many different lymphocytes but each only respond to one antigen.

• when an antigen enters the body, its specific lymphocyte is activated and begins cloning itself and producing antibodies
• this is called clonal selection, as the right lymphocyte is selected then cloned

Question 13

Antibiotics

Answer 13

antibiotics are drugs that prevent or treat the invasion of prokaryote bacteria

they do this by destroying cell structures or metabolic pathways in fungi and bacteria

• destroy cell wall and membranes
• stop protein synthesis (translation)
• stop dna/rna synthesis
• stop metabolic chains (enzyme function)

Question 14

Antibiotic resistance

Answer 14

causes:
- not finishing prescription
- overprescribing
- lack of new antibiotics being developed

The indiscriminate use of antibiotics has led to antibiotic resistance in bacteria.

Evolution by natural selection:

• bacteria mutates and resistance to an antibiotic naturally arises
• bacteria divide rapidly and therefore a resistant strain of bacteria can quickly proliferate
• over time strains of bacteria can become resistant to multiple strains of bacteria

Question 15

An example of antibiotic resistance

Answer 15

methycillin is uses
MSSA - dies
MRSA - survives

mrsa reproduces
resistant gene proliferates

mrsa population increases and becomes dominant strain
methycillin is no longer effective

Question 16

HIV steps

Answer 16

HIV is retrovirus: it inserts its rna into a host cell, which then incorporates that rna into its own dna

• HIV attacks CD4+ macrophages, by attaching to its surface protiens
• once inside the macrophages, it inserts its rna into the macrophages genome
• Transcription now includes the HIVs code, resulting in an output of more viral rna- and subsequent transcription to HIV particles.
• Less antibodies are produced and the immune system is weakened

There is no cure :(

Question 17

HIV and AIDS

Answer 17

HIV is a virus that gradually attacks our natural immune systems, making it more difficult for our bodies to fight other infections and disesies.

AIDS is a syndrome that arrises when HIV reaches a critical point, and the body is too weak and can no longer fight infections. If left untreated, it will likely end in death.