VCE Biology Question Thread

[Rachelle]

Are epitopes and antigen fragments the same thing?

Also, how do I explain the delay in the adaptive immune response and why it is slower than the innate response?

My answer: the adaptive response is antigen-specific, and thus specific lymphocytes must bind to an antigen in order to elicit a response. It takes time for a lymphocyte to find and bind to its specific antigen, leading to a delay. The innate response is faster as it is non specific and hence a specific leukocyte isn't required.

This seems verbose and not accurate enough. Can anyone help?

Yeah they are the same. They are like protein fragments of a larger molecule.
I think that answer is reasonable, and you can also mention that the process of cloning the lymphocytes is necessary before an adequate amount of lymphocytes is made to fight off the infection. The innate immune response is quicker in that there are existing mechanisms and can act upon the invader immediately uponn entry. And yes, a specific leukocyte isn't required.

[soNasty]

Few questions to ask!


- Are bacterial pathogens able to cause a systemic immune response through the release of an exotoxin which destroys phagocytes?
- These action potential graph things:
... can the amplitude of the action potential be increased if the strength of the impulse is increased? or does it remain the same amplitude always?
- Enzymes can have more than one active site.. right?
- T Cells and B cells work together in such a way that the T cells HAVE to release interleukins in order for the B cells to proliferate? or can this occur without Th Cells?

[grannysmith]

http://www.cliffsnotes.com/sciences/anatomy-and-physiology/the-immune-system-and-other-body-defenses/humoral-and-cell-mediated-immune-responses

How accurate are the points made in the above page?

[grannysmith]

Can someone check my description of cell mediated immunity?

A helper T cell binds to an antigen-MHC II complex on an APC specific to its receptor. The APC releases interleukin 1, which stimulates the helper T cell to proliferate and differentiate into more helper T cells, cytotoxic T cells and memory T cells specific to the antigen. It also releases interleukin 2, which stimulates naive B cells into proliferating and differentiating.

Does interleukin 2 also stimulate the naive cytotoxic T cells that differentiated from the original helper T cell to recognise infected cells bearing antigens their MHC I markers?

I just can't seem to condense succinctly..

[katiesaliba]

what is the purpose of the nucleolus? I've never really known this 

[Reus]

what is the purpose of the nucleolus? I've never really known this 

Production of/transcribe ribosomal RNA (rRNA)

[Reus]

Could someone explain what the P and A site are? (Translation, mRNA-rRNA)\

Thanks.

[melons]

A helper T cell binds to an antigen-MHC II complex on an APC specific to its receptor. The APC releases interleukin 1, which stimulates the helper T cell to proliferate and differentiate into more helper T cells, cytotoxic T cells and memory T cells specific to the antigen. It also releases interleukin 2, which stimulates naive B cells into proliferating and differentiating.

Do we need to know this much detail about it?

[melons]

What is the movement of organelles within a cell called? And are we expected to know this, because I don't think we've been taught this?

[Reus]

What is the movement of organelles within a cell called? And are we expected to know this, because I don't think we've been taught this?

I'm not too sure what you mean by the name of the movement within a cell, however the cytoskeleton of a cell is composed of a network of protein fibres that supply the cell with stability and allow it to manoeuvre. In eukaryotic cells, the proteins are arranged as microtubules and microfilaments. Hence the cytoskeleton provides an internal framework/structure for the cell, which preserves its shape and holds its organelles in position. I guess you could also say the cytosol also assists in this (internal fluids).

Also flagella if we're talking about prokaryotic cells.

Note I didn't quite answer your question, as you asked for the name of the movement whereas I told you what causes the movement. 

[melons]

I'm not too sure what you mean by the name of the movement within a cell, however the cytoskeleton of a cell is composed of a network of protein fibres that supply the cell with stability and allow it to manoeuvre. In eukaryotic cells, the proteins are arranged as microtubules and microfilaments. Hence the cytoskeleton provides an internal framework/structure for the cell, which preserves its shape and holds its organelles in position. I guess you could also say the cytosol also assists in this (internal fluids).

Also flagella if we're talking about prokaryotic cells.

Note I didn't quite answer your question, as you asked for the name of the movement whereas I told you what causes the movement. 

Thank you. Yes, I've had difficulty finding the name (google wasn't much help either). It's just that I have a question from some homework which asks me to name it...

Also, will the vacuole in a plant cell become visible after staining?

[Reus]

Thank you. Yes, I've had difficulty finding the name (google wasn't much help either). It's just that I have a question from some homework which asks me to name it...

Also, will the vacuole in a plant cell become visible after staining?

Haha yep I've never had to name it nor been told the name.

Ah yes, it's what a stain does! I remember that the nucleus, chloroplast, ribosomes, mitochondria and the vacuole absorb the most stain/most visible under a microscope (after incubation/maceration)

Note, it really is dependent on the stain, but yes a vacuole does become visible.

[melons]

Haha yep I've never had to name it nor been told the name.

Ah yes, it's what a stain does! I remember that the nucleus, chloroplast, ribosomes, mitochondria and the vacuole absorb the most stain/most visible under a microscope (after incubation/maceration)

Note, it really does dependent on the stain, but yes a vacuole does become visible.

Haha. It's a weird question. 

Thanks again! 

[grannysmith]

I remember this from unit 1/2. The movement of cytosol and organelles within a cell is called cytoplasmic streaming.

[melons]

I remember this from unit 1/2. The movement of cytosol and organelles within a cell is called cytoplasmic streaming.

Thank you very much!!!