VCE Biology Question Thread

[Hirul1280]

Thanks folks

[C14M8S]

Would it be right to say that Interferons cause nearby cells to become more resistant to disease by causing them to produce antiviral enzymes and by summoning Natural Killer cells?

[Erutepa]

Would it be right to say that Interferons cause nearby cells to become more resistant to disease by causing them to produce antiviral enzymes and by summoning Natural Killer cells?

Yes. This would be a good explanation, except rather than resistant to disease, call it a mechanism by which virus spread is reduced.
Interferons are signaling molecules which can be expressed as a paracrine signal by a virus-infected cell. This will be received by neighboring cells to:
 - reduce protein production by destroying mRNAs (thus preventing the production of virus proteins)
 - Increase MHC class I protein expression (greater presentation of virus proteins if present in cell assisting Tc cells)

They can also act as chemoattractants for NK cells in the extracellular environment.

[PhoenixxFire]

Would it be right to say that Interferons cause nearby cells to become more resistant to disease by causing them to produce antiviral enzymes and by summoning Natural Killer cells?

I wouldn't say it makes them more resistant. I'd say it helps prevent the virus from spreading or something like that. Interferon's role is actually a bit more complex. It basically severely reduces the amount of peptides a cell is making and puts out more MHC1, meaning it's more likely to be apoptised if it is infected. It's not really resistance as such.

[Hiea]

What are the roles of beta pleated sheets and alpha helices? As in, what do they really do for the function/structure of the protein?

[Poet]

I wouldn't say it makes them more resistant. I'd say it helps prevent the virus from spreading or something like that. Interferon's role is actually a bit more complex. It basically severely reduces the amount of peptides a cell is making and puts out more MHC1, meaning it's more likely to be apoptised if it is infected. It's not really resistance as such.

I was literally just studying this haha

A complement protein complex punches holes in a bacterial/cell membrane and causes cell lysis - do they do anything else I need to know?

[PhoenixxFire]

What are the roles of beta pleated sheets and alpha helices? As in, what do they really do for the function/structure of the protein?

You don't need to know. Just know that they exist.

I was literally just studying this haha

A complement protein complex punches holes in a bacterial/cell membrane and causes cell lysis - do they do anything else I need to know?

Interferon is actually so cool!

They stick to extracellular pathogens and make them easier for phagocytes to find, and they're chemoattractants (whatever that means) and attract phagocytes to the area.

[AnonymooseUser]

From VCAA 2015 SA Question 4
'Explain how an effective vaccine could provide long-term immunity to EVD.'

Since EVD is a virus, wouldn't memory T cells also be activated in addition to memory B cells?
The exam report only mentions memory B cells and antibodies.

[Erutepa]

I was literally just studying this haha

A complement protein complex punches holes in a bacterial/cell membrane and causes cell lysis - do they do anything else I need to know?

A single compliment protein doesn't punch a hole in the membrane as much as a complex of them do (the membrane attack complex)
They also act as opsonins, chemoattractants and can bind to mast cells to prompt release of inflammatory mediators.

From VCAA 2015 SA Question 4
'Explain how an effective vaccine could provide long-term immunity to EVD.'

Since EVD is a virus, wouldn't memory T cells also be activated in addition to memory B cells?
The exam report only mentions memory B cells and antibodies.

Vaccines can be designed to induce cytotoxic T cell activity, however for our course we only need to talk about it relating to B cells and antibodies (I think)

[Bri MT]

I was literally just studying this haha

A complement protein complex punches holes in a bacterial/cell membrane and causes cell lysis - do they do anything else I need to know?

I remember them by coat, lyse, attract
they coat pathogens
lyse pathogens (what you've decribed)
attract phagocytes

[C14M8S]

1) For the context of VCE, does carrier protein = active transport and channel protein = facilitated diffusion?
2) Does fossilization occur due to minerals flowing in to the bone while it is under pressure?

[PhoenixxFire]

From VCAA 2015 SA Question 4
'Explain how an effective vaccine could provide long-term immunity to EVD.'

Since EVD is a virus, wouldn't memory T cells also be activated in addition to memory B cells?
The exam report only mentions memory B cells and antibodies.

The examiners report just says memory cells, I'd take that to mean both memory B and T cells. It's actually really interesting that they want you to refer to humoral immunity (antibodies) as well.

1) For the context of VCE, does carrier protein = active transport and channel protein = facilitated diffusion?
2) Does fossilization occur due to minerals flowing in to the bone while it is under pressure?

1. Still not really sure on this because it's actually not true.

2. It can either be fossilised as the bone disintegrates, or the Earth can form a mould and the bone can be completely gone and then it's later filled with minerals.
Note that this is only for true fossils - there are other sorts of fossils (moulds, casts, etc) and that C14 dating can only be used when there is still organic matter.

[Bri MT]

From VCAA 2015 SA Question 4
'Explain how an effective vaccine could provide long-term immunity to EVD.'

Since EVD is a virus, wouldn't memory T cells also be activated in addition to memory B cells?
The exam report only mentions memory B cells and antibodies.

memory T cells are ignored in the study design, so don't worry about that aspect

SD: "the characteristics and roles of components of the adaptive (specific) immune response including the actions of B lymphocytes and their antibodies (including antibody structure) in humoral immunity, and the actions of T helper and T cytotoxic cells in cell-mediated immunity. "

[Erutepa]

1) For the context of VCE, does carrier protein = active transport and channel protein = facilitated diffusion?
2) Does fossilization occur due to minerals flowing into the bone while it is under pressure?

1. Carrier proteins can do facilitated diffusion and active transport. Channel proteins can only facilitate diffusion.
2. Fossilization can be:
 - Mineralization whereby minerals replace the hard structures of the organism over time by leaching into the tissue.
 - Molding whereby rock forms around structures which eventually decays, leaving an empty mold
 - casting whereby a mold becomes exposed (or for things like animal impressions in mud) and is filled in by usually ash or lava, creating a cast.
Only very rarely will soft tissues survive preserved in rock (but it can happen)
Also, make sure you know conditions needed for fossilization (I think they are more important). These are things like:
 - Anaerobic/low oxygen to stop tissue decay
 - acidic conditions (for preserving soft tissue) OR alkaline conditions (if you want to preserve hard parts like bones)
 - A rapid burial (to stop dispersal or damage of the organism)

[Globe]

Do we need to know the temperatures for the stages of DNA Hybridisation? Ik they are picky about it for PCR but surely not DNA Hybridisation....