VCE Biology Question Thread

[vox nihili]

How do the B cells in the lymph nodes get activated? Do the antigens wander through the body until they encounter a B cell with the matching antibodies in the nodes?or does an APC travel from the site of infection to the nearest node to activat the B cells?

Interesting question, shows you're really thinking about this.
You don't need to know for VCE, but the APC comes to the node.

[qazser]

Swapping into bio 1/2, an key info i need to get a good grasp of before unit 2?

[vox nihili]

Swapping into bio 1/2, an key info i need to get a good grasp of before unit 2?

Would be a good idea to know some basic features of cells and a little bit about the different molecules that make them up (proteins, nucleic acids, carbs and lipids). The course is fairly new and unit 2 is fairly good now, so enjoy it.

[TheAspiringDoc]

Would be a good idea to know some basic features of cells and a little bit about the different molecules that make them up (proteins, nucleic acids, carbs and lipids). The course is fairly new and unit 2 is fairly good now, so enjoy it.

I've just done U1, and I think quite a lot carries over to unit 3. So if you want to be up with the other students on that, maybe take a look at enzymes, organelles, the cell membrane, and all that good stuff.

[qazser]

Would be a good idea to know some basic features of cells and a little bit about the different molecules that make them up (proteins, nucleic acids, carbs and lipids). The course is fairly new and unit 2 is fairly good now, so enjoy it.

I've just done U1, and I think quite a lot carries over to unit 3. So if you want to be up with the other students on that, maybe take a look at enzymes, organelles, the cell membrane, and all that good stuff.

Cheers Guys

[plsbegentle]

I've just done U1, and I think quite a lot carries over to unit 3. So if you want to be up with the other students on that, maybe take a look at enzymes, organelles, the cell membrane, and all that good stuff.

wait are u only yr 10, just out of curiosity?

[TheAspiringDoc]

wait are u only yr 10, just out of curiosity?

Last time I checked, it seemed that way. What tickles ur fancy

[plsbegentle]

just surprised how smart you are for a year 10, keep up the good work fam

[Photon]

Interesting question, shows you're really thinking about this.
You don't need to know for VCE, but the APC comes to the node.

But can't antigens also wind up in lymph nodes too? Considering the lymphatic system filters the interstitial fluid (which contains plasma).

[vox nihili]

But can't antigens also wind up in lymph nodes too? Considering the lymphatic system filters the interstitial fluid (which contains plasma).

Sure can. But free antigen only activates B-cells, whereas antigen needs to be presented to activate T-cells.

[kupus]

Hi, quick thing I could use clarification on.

In a single stranded chromosome, there would be 2 molecules of DNA, correct? Since there are two chromatids?
And, for example, in a homologous pair of chromosomes there would be 8 DNA molecules?
I'm unsure what constitutes a molecule of DNA.

[solution]

Hi, quick thing I could use clarification on.

In a single stranded chromosome, there would be 2 molecules of DNA, correct? Since there are two chromatids?
And, for example, in a homologous pair of chromosomes there would be 8 DNA molecules?
I'm unsure what constitutes a molecule of DNA.

No, in a single stranded chromosome there is only one molecule of DNA (the DNA molecule is a double helix, but the double helix is counted as a single DNA molecule). A single stranded chromosome is not referred to as a chromatid, but as a chromosome. When it divides it is still one chromosome, however it becomes double stranded (hence, it is made of 2 sister chromatids). Although it is referred to as one chromosome, there are 2 DNA molecules (think about it, the DNA has replicated).

In a homologous pair of chromosomes there would be 4 DNA molecules (assuming you mean double stranded chromosomes).

[kupus]

No, in a single stranded chromosome there is only one molecule of DNA (the DNA molecule is a double helix, but the double helix is counted as a single DNA molecule). A single stranded chromosome is not referred to as a chromatid, but as a chromosome. When it divides it is still one chromosome, however it becomes double stranded (hence, it is made of 2 sister chromatids). Although it is referred to as one chromosome, there are 2 DNA molecules (think about it, the DNA has replicated).

In a homologous pair of chromosomes there would be 4 DNA molecules (assuming you mean double stranded chromosomes).

Ahh okay. I get it now. Thanks heaps!

[HasibA]

any help with these?
'how does the OH group on a complementary strand of DNA allow it to replicate'- what are they asking lol, help plz
we have to know about Poly-A tails and Methyl caps, but is that 'it' we have to know (not sure what to label theses concepts under )
do we have to know about okazaki fragments?
other than to conserve energy and resources, what is another purpose of gene regulation ? can't really think of more than those
also, last q, what enzymes do we have to know when talking about dna replication? ive got dna helicase, rna polymerase and dna polymersae- what else?

thanks guys )

[Yacoubb]

any help with these?
'how does the OH group on a complementary strand of DNA allow it to replicate'- what are they asking lol, help plz
we have to know about Poly-A tails and Methyl caps, but is that 'it' we have to know (not sure what to label theses concepts under )
do we have to know about okazaki fragments?
other than to conserve energy and resources, what is another purpose of gene regulation ? can't really think of more than those
also, last q, what enzymes do we have to know when talking about dna replication? ive got dna helicase, rna polymerase and dna polymersae- what else?

thanks guys )

In polynucleotide synthesis, the nucleotides added by DNA polymerase are added to the 3' OH group of the existing strand. Without that 3' OH group, nucleotides cannot be added to the strand being synthesised, and hence is fundamental to the replication of the strand.

Yeah just know that the addition of a methyl cap at the 5' end and a poly-A tail to the 3' end of the mRNA transcript are events that occur in post-transcriptional modification.

Just know that Okazaki fragments are short fragments of DNA produced by the discontinuous synthesis of the lagging strand during DNA replication.

An important component of gene regulation (which I suppose complements the conservation of energy) is that proteins that do not need to be synthesised in a particular cell are not synthesised. E.g. the enzymes responsible for expression of genes associated with eye colour do not need to be expressed within a skin cell.

Enzymes: DNA helicase, DNA polymerase, DNA ligase, DNA topoisomerase/gyrase. Remember RNA polymerase is for transcription in gene expression.

Good luck