Comuciable Diseases, Disease Prevention And Immune System

Question 1

What are communicable diseased caused by?

Answer 1

Pathogens: viruses, bacteria, fungi, Protoctista

Pathogen cause harm through directly damaging tissue of through the release of toxins

Question 2

Give examples of pathogens and types:

Answer 2

Bacteria: ring rot and TB

Fungi: athletes foot black Sigatoka

Virus: tobacco mosaic virus, influenza, HIV

Protoctista: malaria, tomato late blight

Question 3

Tuberculosis:

Answer 3

Bacterial

Transmitted through airborne droplets, more prevalent where people live in cramped conditions

Causes harm by damaging lung tissue and suppressing immune system

Cured through antibiotics, prevented through vaccination

Question 4

Ring rot:

Answer 4

Bacterial

Potatoes, tomatoes and aubergines

Damages leaves, tubers and fruit

Transmitted through micropropagation and infected tubers from infected plants

Reduces crop of plant so affects livelihood of farmers

Question 5

viruses

Answer 5

Virus - non living and a cellular: they consist of genetic material, a capsid and attachment protein, they are smaller than bacteria.

Viral replication occurs inside of host cells, involves injection of genetic material into host cell

Question 6

Influenza

Answer 6

Virus - non living and non cellular

Infects Ciliated cells that ling the walls of gas exchange surfaces

Young children and elderly or anyone with lowered immune system are at higher risk of severe symptoms of dying of influenza

Transmitted by airborne droplets

Question 7

Black Sigatoka

Answer 7

Fungi

Infects banana

Turn leafs black

Transmitted by spores in wind

Fungicides can kill it and resistant strains have been developed

Question 8

Malaria

Answer 8

Protoctista

Caused by plasmodium and spread by vector of mosquito

Reproduces sexually and asexually

When mosquitos bite and take blood from human

Affects RBC, liver, brain

Preventative medicine, no cure or treatment

Question 9

Tomato / potato late blight

Answer 9

Protoctista

Fungi like protoicsta

Hyphae enters plant and causes damage to leaves and fruits

Transmitted by spores which travel in the wind or are transferred by animals and insects from one plant to another

No cure, resistant strains developed

Question 10

Athletes foot

Answer 10

Fungi

Type of ringworm that thrive sin warm damp regions, between toes

Causes skin to crack and become scales, itchiness and soreness

Transmitted by direct contact e.g wearing same socks ans infected person

Cured using anti fungal creams

Question 11

HIV

Answer 11

Virus

Transported around in blood until it attaches to a protein on the T helper cells

AIDs is when replicating virus in T helper cells interferes with normal functioning of immune system

Human is unable to produce adequate immune response to other pathogens so they are left vulnerable to infections and cancer

Transmitted through direct contact by transmission of bodily fluids

Question 12

Tobacco mosaic virus

Answer 12

Virus

Infects plants

Damage to leaves - mosaic pattern, damaged flowers and fruits, damage prevents plant from growing

Transmitted when infected leaves touch healthy leaves or if gardeners use contaminated tools

No cure

Question 13

What are Protoctist?

Answer 13

Eukaryotes that exist as single celled organisms or cells grouped into colonies

Infect hosts

Parasites transmitted via vector

Question 14

What living conditions make transmssion more likley?

Answer 14

Hot climates: more KE for chemical reactions and reproduction

Social factors:
- poverty - poorer sewage infrastructure, lack of fresh water and food.
- Poorer sanitation
- overcrowded living
- medicines and vaccines less readily avaliable to prevent spread

Transport:
Diseases can be spread between countries

Question 15

Modes of transmission in animals:

Answer 15

Direct:
-direct contact - touch
- inoculation: animal bits, needles, cuts in skin
- ingestion: drinking or eating contaminated water/food

Indirect:
- vectors: animals that pass pathogen to human
- droplets: airborne droplets from cough or sneeze
- fomites: inanimate objects that carry and transmit pathogen - dirty bedding, socks or cosmetic

Question 16

Modes of transmission in plants

Answer 16

Direct:
- direct contact: leaves touching

Indirect:
- vector: spores travel in wind, by animal
- contaminated soil

Question 17

Plant defence responses:

Answer 17

No immune system or blood
1. Barriers - bark or waxy cuticles
2, antibacterial chemical and proteins which can repel and kill pathogen or insects
3. Physical defences that prevent pathogens spreading between cells once infected: callose

Question 18

Animal immune responses:

Answer 18

Primary: non specific meaning same response will happen regardless of the pathogen

Secondary:

Question 20

Primary responses:

Answer 20

Barriers:
- mucus membranes - line tracts, traps pathogens and Ciliated cells sweep mucus away
- lysozymes - hydrolytic enzymes which digest pathogens
- blood clots - scab formation where there is a cut to prevent pathogen entry
- skin - contains microorganisms that can outcompete pathogens

Expulsion reflexes:
- sneezing
- coughing
- vomiting

Inflammation: when cells are damages mast cells release histamines and cytokines

Histamines cause blood vessels to dilate and therefore more blood is flowing in this area. The increased temperature from blood kills pathogens. Histamines can also make the walls of blood vessels more permeable so more WBC cab be delivered to site of damage

Inflammation results in redness, swelling and itchiness

Cytokinesis attract phagocytes

Question 21

Phagocytosis:

Answer 21

Phagocytes (macrophages or neutrophils) travel in blood and squeeze out of capillaries to engulf dn digest pathogens.

Non specific response

Damaged cells and pathogens release cell signaling chemicals - cytokinesis that attract phagocytes to site of infection

Poisoning protein can attach to pathogen to mark them so macrophages and neutrophils

1. Phagocytes identify pathogen - have receptors that attach to chemicals on the surface of pathogen
2. They engulf them by Endocytosis by forming a vesicles around them
3. This vesicle is called a phasgosome
4. Phagocyte contains lysosomes containing hydrolytic enzymes which digest and breakdown pathogen because lysosome fuses with phagosome
5. Broken down material from pathogen is released by Exocytosis or if it is useful, it is absorbed by the cytoplasm and used in the cell
6. The antigen of the pathogen is presented on the phagocyte at the MHC and the phagocyte is now an antigen presenting cell (APC)

Question 22

Second line of defence:

Answer 22

If non of the primary responses stopped pathogen from entering:

Specific to antigens

Involves B lymphocytes and T lymphocytes, both of which are created by bone marrow stem cells

B cell mature in the bone marrow but T cells mature in thymus

Question 23

Cell mediated response:

Answer 23

Receptors on T cells bind to complimentary shaped antigens on APCs, causes T cells to divide rapidly by mitosis (Clonal expansion)

—»Once attached, interleukins are produced which activates T helper cells to divide by mitosis to replicate and make large numbers of clones

Cloned T helper cells differentiate into different cells (Clonal selection)

• remain as T helper cells and release interleukins to activate B lymphocytes and more phagocytosis
• T killer cells - destroy abnormal or infected cells by releasing Perforin which embeds in cell surface membrane and makes a pore so any substance can enter or leave and thsi causes cell death (most common in viral infections)
• T memory cells will retain shape for specific antigen in case there is a second infection
• T regulator cells that suppress immune response to ensure the cell mediated response only occurs when pathogens are detected

Question 24

What could an APCs be?

Answer 24

Infected body cell presenting viral antigens on surface

A macrophages which has engulfed and destroyed a pathogen presenting antigens on its surface

Cells of a transported organ which will have different antigen shapes compared to self call antigens

Cancer cells also have abnormal shaped self antigens

Question 25

Humoral response (B lymphocytes)

Answer 25

PRIMARY IMMUNE RESPONSE T helper cell binds to B cell with complimentary antibody to antigen. (Clonal selection), B cell is then actiavted by the release of interleukins from T helper cells B cells rapidly divide by mitosis to make clones which differentiate in B memory cells or plasma cells (Clonal expansion) Plasma cells produce antibodies Antibodies: 1. Agglutination - clumping together of pathogens so it is easier for phagocytes to locate and engulf 2. Marking pathogen - act as opsonin, when an antibody antigen complex has been formed, antibodies are marking teh antigen making them for susceptible to phagocytes 3. Acting as an anti toxin - can bind to toxins being produced by pathogen which will prevent them from entering cells and causing harm SECONDARY RESPONSE If reinfection occurs of the same pathogen, B memory cells which remain in blood can rapidly produce large amounts of antibodies

Question 26

What is an antibody?

Answer 26

Globular, quaternary stucture protein that has 4 polypeptide chains: 2 light and 2 heavy It has a variable region which is different for every antibody this is where there is a unique 3D shape that is complimentary to an antigen binding sites which is where antigens bins, hinge region that allow flexibility so more antigens bind, constant region which is the same for all antibodies

Question 27

Differences in primary and secondary immune responses:

Answer 27

First exposure to pathogen is described as the primary immune response Can take a few days for lymphocytes to create enough complementary antibodies sto destroy pathogen so symptoms happen In second exposure, memory cells mean antibodies can be rapidly produces so pathogen is destroyed before symptoms are shown ACTIVE IMMUNITY

Question 28

What is an autoimmune disease?

Answer 28

When immune system identifies own body cells as non self and therefore potentially harmful to the body Body recognises antigen on some body cells as non self and produces antibodies against them. Cells are attacked or damaged which causes the symptoms of the disease Immune system can overreact or mild pathogens or the T regulator cells do not work properly so immune response isn’t regulated E.g rheumatoid arthritis - immune system attacks cartilage in joints

Question 29

Why are vaccines not always effective long term?

Answer 29

Pathogens genetic material cna mutate and result in a pathogen producing a different shaped antigens. This is antigen variability It means that B memory cells have a receptor that is no longer complimentary to antigen so no longer immune Thsi is why there are boosters vaccines e.g flu vaccine - annual

Question 30

How do vaccines prevent epidemics and pandemics?

Answer 30

Mass vaccination programmes prevent further spread of pathogen. If large enough proportion of the population are vaccinated, herd immunity arises and it is unlikely that susceptible individual will encounter an infected individual The vaccines are frequently updated, resulting in booster vaccines to account for antigen variability

Question 31

Sources of medicine:

Answer 31

Many t medicines have been sourced from microorganisms and plant >>> this is why biodiversity is key, it may contain more sources for medicine that have been undiscovered microorganism - penicillin, vancomycin Plants - aspirin (willow bark), digitoxin (foxglove)

Question 32

Importance in maintaining biodiversity for medicine:

Answer 32

Increases the chances of finding more new drugs Need to make sure genetic resources are maintained for future Many modern drugs have been made using knowledge of traditional remedies Once a species is extinct, its genetical and potential medicines are lost forever

Question 33

Old vs new medicines:

Answer 33

Old - sourced form plants New - personalised medicine: everyone is different so we respond differently to different medicines, gene technology enables us to predict diffent peoples responses to medicine. By analysing DNA, suitable drugs and dose can be figures out - pharmacogenetcs Synthetic biology: synthetic manufacture of medicines including genetic engineering of insulin. Using cells as medicine factories, combined gene sequencing, bioinformatics and computational biology to find out the base sequence of a protein and store the data digitllly and make 3D models and simulations before physically producing a medicine in a labatory

Question 34

Antibiotic resistance:

Answer 34

Random mutations of bacterial Could be a mutation that codes for a new protein that provides protection against antibiotic so bacteria has a selective advantage so are more likley to survive More likley to survive, reproduce and pass on mutated allele to population, whole population become resistant. Widespread use and misuse of antibiotics have caused this