BIO MOD 7: depth study

Question 1

define cytokine

Answer 1

Signalling molecules. They are small membrane-bound proteins secreted by cells that regulate immune responses and can modulate the functions of individual cells. They can both stimulate and slow down the immune system.

Question 2

define cytokine storm

Answer 2

A hyper-activation of the body’s immune response. It is a severe immune reaction where the body releases too many cytokines into the blood too quickly.

Question 3

define leucocyte

Answer 3

WBC. A type of blood cell made in the bone marrow and found in the blood and lymph tissue. They help the body fight infection and other diseases.

Question 4

what is a monocyte

Answer 4

A type of WBC that can differentiate into macrophages and dendritic cells to elicit an immune response. They are the largest type of leucocyte in blood.

Question 5

what are neutrophils

Answer 5

They are one of the first immune cells to respond to foreign microorganisms. They travel to the site of infection and destroy the invader by ingesting and releasing enzymes that kill them. They also boost the response of other immune cells.

Question 6

what are macrophages

Answer 6

They are phagocytes that phagocytose pathogens and are also long-lived (several months) antigen-presenting cells that present antigens to B and T cells. They are important in the process of recognising cells that have been bound by antibodies and destroying them.

Question 7

what is an NK cell

Answer 7

A type of immune cell that has granules with enzymes that can kill tumour cells or cells infected with a virus. They induce apoptosis within infected body cells. NK cells do not require activation.

Question 8

what is a dendritic cell

Answer 8

Antigen-presenting cells found in tissues such as the skin, and boost immune responses by showing antigens on its surface to other cells of the immune system.

Question 9

what are CD4T cells

Answer 9

‘helper T cells.’

They help fight infection by triggering your immune system to destroy pathogens. They mediate the immune response by directing other cells but cannot directly kill infected cells or pathogens. They also regulate the type of immune response that develops.

Question 10

what are CD8T cells

Answer 10

‘cytotoxic T cells.’

They destroy cells infected by foreign agents and kill tumour cells by expressing appropriate antigens. They activate when signals that prevent them from attacking (MHC I molecules) are absent on a target cell.

Question 11

what are interleukins

Answer 11

A type of cytokine produced by leucocytes and other body cells. They play essential roles in the activation, differentiation and growth of immune cells.

Question 12

what does D.I.C stand for? and what condition is it?

Answer 12

Disseminated Intravascular Coagulation.

A condition that causes abnormal blood clotting throughout the body’s blood vessels. It is an acquired syndrome characterised by widespread activation of coagulation. You may develop DIC if you have an infection or injury that affects the body’s normal blood clotting.

Question 13

what does A.R.D.S stand for? and what condition is it?

Answer 13

Acute Respiratory Distress Syndrome.

A serious lung condition that causes low blood oxygen; fluid builds up inside the tiny air sacs (alveoli) in the lungs. The fluid keeps your lungs from filling with enough air, causing less oxygen to reach your bloodstream.

Question 14

what is anemia?

Answer 14

Anemia is a condition that results from a lack of healthy red blood cells to carry sufficient oxygen to the body’s tissues, leading to reduced oxygen flow to the body’s organs.

Question 15

what are phagocytes

Answer 15

A class of WBC. They can exit the blood vessels and move into tissues to destroy invading pathogens at the site of entry. They contain lysosomes, which are enzymes that break down and destroy pathogens. Following the destruction of the pathogen, they may release cytokines.

Question 16

what are antibodies

Answer 16

Small proteins produced by the body that can recognise and bind to antigens that have invaded the body. They can ‘flag’ them as foreign, and assists the body’s cells in isolating and neutralising them. One antibody only recognises one specific antigen

Question 17

which antibodies are thought to be a treatment for COVID-19?

Answer 17

IgG, IgE, IgD, IgM, IgA

Question 18

what are antigens?

Answer 18

A protein or carbohydrate complex that triggers an immune response, and is usually found on the surface of pathogens.

Question 19

how can COVID-19 trigger a cytokine storm?

Answer 19

When the virus invades the body, it can cause an imbalance in the immune system. Following cell invasion, the virus replicates in large quantities, activating immune cells and a release of a large number of inflammatory cytokines, leading to a cytokine storm.

Question 20

how do antiviral drugs work?

Answer 20

They do not kill the target pathogens but rather inhibit their development. They can block receptors so viruses are unable to bind to and enter healthy cells. They can also boost the immune system and lower the viral load (amount of active virus) in the body. Antivirals also lower the risk of getting or spreading viruses.

Question 21

why do viruses mutate?

Answer 21

Due to its high replication rate because of its smaller genomes, its genes have a large chance to undergo random ‘copying errors’ (i.e. genetic mutations), which over time can lead to alterations in the virus’ surface proteins or antigens.

Question 22

what is antigenic shift?

Answer 22

Antigenic shift occurs when a virus undergoes a sudden change in its genetic makeup, thereby creating a new strain.

Question 23

what is antigenic drift?

Answer 23

Antigenic drift occurs when a virus undergoes a gradual change in its genetic makeup, causing a different, but somewhat similar genetic makeup to the parent virus.

Question 24

why does virus mutation pose a problem for antiviral drugs?

Answer 24

Because viruses mutate so quickly and frequently, it is difficult for antiviral drugs to be developed as they must be constantly updated to fight against the new strain. In addition, as viruses use and hijack the host’s cellular machinery to replicate, it’s hard to design a safe and effective antiviral drug. It would have to get inside the infected body cells and act on processes that are essential for the normal functioning of the human body.

Question 25

how do drug manufacturers overcome this problem?

Answer 25

Through continuous surveillance and scientific development as well as collaboration with other manufacturers. They also utilise virus genome sequencing to see how the virus has changed from the past, and are constantly updating their drugs in line with new mutations.

Question 26

what is a virus genome sequence? and what is genome sequencing?

Answer 26

The sequence or order of bases or letters that make up a virus’ genetic material; or its genome. Genome sequencing is the process scientists use to figure out the right order of letters in a certain sample of a virus.

Question 27

why are virus genomes mapped?

Answer 27

Genomic analysis is a powerful tool for understanding viral disease outbreaks. Genome sequencing can reveal many useful things; it can identify a new virus, identify what kind of virus is causing illness, and give an idea of how a virus may cause disease based on its genes and the proteins they encode, along with ways to try and stop it. It also shows the physical trails of the virus and where it has invaded.

Question 28

what viral diseases have antiviral drugs?

Answer 28

COVID-19, ebola, influenza, herpes, Hep B + C, HIV

Question 29

what are the 2 main antiviral drugs used for COVID-19?

Answer 29

Paxlovid + Lagevrio

Question 30

explain the link between anti-RNA polymerase and protein synthesis

Answer 30

The role of RNA polymerase in protein synthesis is to transcribe DNA to mRNA. Anti-RNA polymerase disrupts the translation of the virus’ RNA in order to stop it from effectively replicating.

Question 31

does SARS-CoV-2 contain DNA or RNA?

Answer 31

RNA

Question 32

are viruses with DNA or RNA more likely to mutate?

Answer 32

RNA viruses are more likely to mutate. Unlike DNA, RNA viruses do not have DNA polymerase and instead have RdRp (RNA-dependent RNA polymerase) which does not have the same ‘proofreading’ ability and are hence unable to correct mistakes during replication, causing more instances of mutation. They also have smaller genomes, which appear to have a correlation with higher rates of mutation.

Question 33

how many variants of COVID-19 have been genome mapped?

Answer 33

14 (?)

Question 34

what is an antibiotic?

Answer 34

They’re medications that combat bacterial infections by either killing the bacteria or inhibiting their development. Antibiotics work by disrupting the vital processes or structures in the bacteria cell, thereby killing them or preventing their spread.

The three main targets for antibiotics:
1. cell wall/membranes that surround the bacteria cell
2. machinery that makes the nucleic acids DNA + RNA
3. machinery that produces proteins

Question 35

how do quinolones work?

Answer 35

By directly killing bacteria cells. The quinolone class of antibiotics inhibits the DNA synthesis of bacteria by disrupting the two critical bacterial enzymes that regulate the chromosomal supercoiling required for DNA synthesis, and by causing the breakage of bacterial chromosomes.

Question 36

how do macrolides work?

Answer 36

By inhibiting protein synthesis by targeting the bacterial ribosome. They bind at the nascent peptide exit tunnel and partially occlude it; macrolides have been viewed as ‘tunnel plugs’ that stop the synthesis of every protein. They suppress and inhibit bacterial growth rather than directly killing it.

Question 37

how do streptogramins work?

Answer 37

By inhibiting bacterial protein synthesis. They obstruct protein synthesis by interfering with peptide bond formation and by blocking the peptide exit tunnel in the large (50S) ribosomal subunit, which prevents the extension of the polypeptide chain.

Question 38

how effective are antibiotics as a treatment strategy for the control of infectious diseases?

Answer 38

Antibiotics are only effective to the extent of controlling infectious diseases caused by bacteria, and while they’re effective at the treatment the disease itself whilst it has already infected an individual, they are not a good method for controlling the spread of disease, as they are not a preventative measure.

Question 39

why are there more COVID-19 deaths in some countries compared to others?

Answer 39

There is a major disparity regarding the available health sector infrastructure in different countries. Some countries simply do not have the economic resources to invest in scientific development and spreading awareness through public health campaigns. Education is also another factor that contributes, as there may be a lack of trained healthcare professionals to look after the control and spread of disease.

Question 40

what COVID-19 vaccines are currently being used in Australia?

Answer 40

Oxford AstraZeneca, Pfizer, Moderna, Novavax

Question 41

what is the difference between vaccination and immunisation?

Answer 41

Vaccination is when you directly receive a vaccine; either through an injection or orally. Immunisation, however, is the process of becoming protected and immune to a disease as a result of a vaccine.

Question 42

how do mRNA vaccines work? give an example.

Answer 42

Pfizer-BioNTech and Moderna.

They work by introducing a piece of mRNA that corresponds to a viral protein, usually a small piece of a protein found on the virus’s outer membrane. They give your cells instructions on how to make the S protein found on the surface of the virus. After vaccination, your muscle cells begin making the S protein pieces and displaying them on cell surfaces, causing your body to create antibodies.

Question 43

how do vector vaccines work? give an example.

Answer 43

Janssen/Johnson & Johnson, Oxford, Ebola.

Viral vector vaccines use a modified version of a virus (a vector) to deliver genetic instructions to the body’s cells. The cells then produce harmless pieces of the virus called antigens which trigger an immune response in the body. They don’t contain antigens, but rather use the body’s own cells to produce them.

Question 44

how do protein subunit vaccines work? give an example.

Answer 44

Novavax.

Subunit vaccines include only the parts of a virus that best stimulate the immune system; i.e. only containing harmless S proteins. Once your immune system recognises the S proteins, it creates antibodies and defensive white blood cells.

Question 45

what are T cells?

Answer 45

A type of lymphocyte; direct fighters of foreign invaders that also produces cytokines.

Question 46

what are B cells?

Answer 46

A type of lymphocyte; B cells produce antibody molecules that can latch on and destroy invading viruses or bacteria.