VCE Biology Question Thread

[vox nihili]

Would the case of Tc and NK cells inducing apoptosis through perforin and granzymes be considered intrinsic or extrinsic apoptosis? I'm thinking it leads to damage within the cell therefore it may cause the release of cytochromes which activate caspases therefore may be intrinsic.

Extrinsic

[TheBigC]

Do cytotoxic T cells and Natural Killer cells stimulate the extrinsic apoptosis pathway?

Really good question.
- INSIDE the scope of the course: VCAA defines the intrinsic pathways as occurring due to an internal signal, and the extrinsic pathways from an external signal. (Sources: VCE Biology Study Design 2016-2021)
- Hence, as granzymes and perforin are secreted externally from the cell (via Tc cells), I believe VCAA (if they ever asked a question on this) would be insinuating that it is part of the extrinsic apoptotic pathway.

[Shaqattack]

just wondering if anyone could explain to me when to talk when u should talk about dendritic cells rather than B cells


I just did a question which said how are antibodies are made and it said in the answers that dendritic cells engulf the antigen present it on its class 2 markers to t h cells which activate B cells which differentiate into b plasma cells. Could u just say the antigen binds to a specific naive B cell  causing the B cell to differentiate into b memory cells and  b plasma cells which produce antibodies
Thanks 

[ezferns]

Could u just say the antigen binds to a specific naive B cell  causing the B cell to differentiate into b memory cells and  b plasma cells which produce antibodies
Thanks 

The binding of specific naive B cell to a raw antigen happens normally as well. Both the dendritic cell presenting to a naive Th and naive B detecting raw antigen happen simultaneously. Then the B and Th meet and the Th stimulates the B to undergo clonal expansion.
In a lot of questions vcaa neglects to mention the role of the Th cell and sometimes they neglect the B cell detecting the raw antigen.
I'm just gonna mention both aspects either way.

[kit_kat15]

Hi, I'm really scared I'm going to fail >.<

I just got around to studying after eng and also have maths tomorrow, how should I spend the rest of my Thursday?

[captkirk]

Hey everyone, in the study design it says we need to know "inputs and outputs of glycolysis..."

Do we just need to know that the inputs are glucose, ADP+pi and NAD or do we need to know the exac numbers. Eg
Glucose, 2ADP+Pi, 2NAD

Thanks

[smamsmo22]

Hi,
Does anyone know how/if exactly recombinant plasmids are inserted into the chromosomes of other species? I understand the whole process from which transformed bacterial cells result, but I don't understand how the recombinant plasmid is applied to cells (e.g, in the sample exam, the recombinant plasmid is used to insert genes into the rice). For the recombinant genes be inheritable in the organism they'd have to be in the chromosomes, right? How would they get there?
Thanks

[PhoenixxFire]

Hey everyone, in the study design it says we need to know "inputs and outputs of glycolysis..."

Do we just need to know that the inputs are glucose, ADP+pi and NAD or do we need to know the exac numbers. Eg
Glucose, 2ADP+Pi, 2NAD

Thanks

Definitly need to know the exact numbers

[ezferns]

Hi,
Does anyone know how/if exactly recombinant plasmids are inserted into the chromosomes of other species? I understand the whole process from which transformed bacterial cells result, but I don't understand how the recombinant plasmid is applied to cells (e.g, in the sample exam, the recombinant plasmid is used to insert genes into the rice). For the recombinant genes be inheritable in the organism they'd have to be in the chromosomes, right? How would they get there?
Thanks

Correct me if I'm wrong but I don't think the plasmid is integrated into the chromosome. The plasmid is just inserted into the plant cell. It replicates independently of the nuclear DNA but is still passed on to daughter cells in mitosis.

[chriskesh23]

Correct me if I'm wrong but I don't think the plasmid is integrated into the chromosome. The plasmid is just inserted into the plant cell. It replicates independently of the nuclear DNA but is still passed on to daughter cells in mitosis.

the bacterial cells undergo a treatment known as electroporation and heat shock. in electroporation, bacterial cells are applied with a shock of electricity which forms pores in the membrane allowing plasma entry, with heatshock the fluidity of the plasma membrane is increased so that plasmid uptake is increased.

[chriskesh23]

hey guys, just a query on introns

why do introns exist in the genetic code if they don't code for anything?

And what purpose do they serve in alternative splicing ?

[rainbowsparkles15]

just wondering if anyone could explain to me when to talk when u should talk about dendritic cells rather than B cells


I just did a question which said how are antibodies are made and it said in the answers that dendritic cells engulf the antigen present it on its class 2 markers to t h cells which activate B cells which differentiate into b plasma cells. Could u just say the antigen binds to a specific naive B cell  causing the B cell to differentiate into b memory cells and  b plasma cells which produce antibodies
Thanks 

I typically say that an antigen presenting cell (such as a macrophage or dendritic cell) presents the foreign antigen on its MHCII marker which binds to the specific B cell and is then activated by specific T Helper cell causing the B cell to differentiate
(that lacks detail but just a shortened explanation as to where dendritic cells fit it in)

[TheBigC]

just wondering if anyone could explain to me when to talk when u should talk about dendritic cells rather than B cells


I just did a question which said how are antibodies are made and it said in the answers that dendritic cells engulf the antigen present it on its class 2 markers to t h cells which activate B cells which differentiate into b plasma cells. Could u just say the antigen binds to a specific naive B cell  causing the B cell to differentiate into b memory cells and  b plasma cells which produce antibodies
Thanks 

No. Your answer would be insufficient. Often, the level of detail required is indicated by the number of marks in the question and the number of lines given. If several marks are required, then I would strongly recommend discussing antigen-presentation with APCs (i.e. dendritic cells)...
Moreover, B cells are not just 'activated' upon engulfment of 'raw' antigens. They need to present these antigens via MHCII to ACTIVATED Th cells, THEN they are activated. This results in proliferation and differentiation into B memory cells and B plasma cells.

[rainbowsparkles15]

Hi, I'm really scared I'm going to fail >.<

I just got around to studying after eng and also have maths tomorrow, how should I spend the rest of my Thursday?

Hey!
Try not to stress, have faith in your abilities and do the best you can

It really does depend on how much content you know- if you only know the bare minimum try and grasp the main parts of each area of study.
Some points to start with may include: protein synthesis, cellular respiration and photosynthesis, signal transduction, overview of the immune response (particular adaptive), natural selection, divergent and convergent evolution, trends in human evolution, recombinant plasmids and scientific method

It may sound like a lot but watching some YouTube videos and completing some practise questions would assist in ensuring you are prepared with the time you have left. Also make use of all the clever AN users by asking questions!
Good luck

[rainbowsparkles15]

hey guys, just a query on introns

why do introns exist in the genetic code if they don't code for anything?

And what purpose do they serve in alternative splicing ?

I'm not certain as to why introns exist but do know they are certainly not 'junk DNA.' They may be involved in gene regulation but I'm not sure.

In alternate splicing, some exons are removed along with the introns