VCE Biology Question Thread

[blacksanta62]

Hello all, I'm a bit confused by these questions. With c) is it because the n(T) and n(C) and n(G) are unknown therefore the amount of A can't be accurately determined?
With d) I'm actually confused with. Doesn't this 2014 chemistry exam question say otherwise? Where the % of A & T = 27% each and the % of C & G = 46% each. If we do what they suggest we don't get 1.

Thanks for the help 
Edit: Yooooo, I was doing (A + T)/(C + G) = 1 (it doesn't!!!) my mistake . Still need help with the other question though

[HighTide]

Hello all, I'm a bit confused by these questions. With c) is it because the n(T) and n(C) and n(G) are unknown therefore the amount of A can't be accurately determined?
With d) I'm actually confused with. Doesn't this 2014 chemistry exam question say otherwise? Where the % of A & T = 27% each and the % of C & G = 46% each. If we do what they suggest we don't get 1.

Thanks for the help 
Edit: Yooooo, I was doing (A + T)/(C + G) = 1, my mistake . It does equal 1. Still need help with the other question though

Complementary binding is in double strand. You can't predict single strand because you can have uneven amounts since theres no complementary binding.
Btw in your edit you switched it around. Make sure you know which ones bind (idk if it was just a typo).

[blacksanta62]

Okay, I see what you mean. What I meant by the edit was that I was adding the complementary ones together and dividing them both hoping they would equal 1 i.e. (A + T)/(C + G) = 1, which it doesn't. I'll clear that up though  

[Gogo14]

Hello all, I'm a bit confused by these questions. With c) is it because the n(T) and n(C) and n(G) are unknown therefore the amount of A can't be accurately determined?
With d) I'm actually confused with. Doesn't this 2014 chemistry exam question say otherwise? Where the % of A & T = 27% each and the % of C & G = 46% each. If we do what they suggest we don't get 1.

Thanks for the help 
Edit: Yooooo, I was doing (A + T)/(C + G) = 1 (it doesn't!!!) my mistake . Still need help with the other question though

For c,
It is ONE DNA strand. Hence you cannot find the amount of A since you do not know base pairings. A could be any amount, so could T. Note T does not equal A because it is not paired.
Whereas in a DOUBLE STRAND, you know that the amount of A=T and C=G because it is paired. So you can deduce the amount of A remaining.

[gameboy99]

I'm really confused... Is DNA replication and transcription the same thing??

[HighTide]

I'm really confused... Is DNA replication and transcription the same thing??

No.
In DNA replication, the DNA is used as a template to make more DNA.
Transcription (in synthesis of proteins) is basically gene expression where the DNA is used to make mRNA, which then goes on to make proteins.
In summary:
DNA replication: DNA-> DNA
Transcription: DNA-> mRNA

[gameboy99]

Thanks Hightide for the explanation.
If it is possible, could somebody write up a step-by-step process of what happens in cell replication including okazaki fragments because I am totally confused. 
Thanks

[plsbegentle]

Thanks Hightide for the explanation.
If it is possible, could somebody write up a step-by-step process of what happens in cell replication including okazaki fragments because I am totally confused. 
Thanks

I'm gonna give u a general process:
-So for DNA to be replicated, the double helix must be unzipped and this is done by DNA helicase.
5' ACTGAAAA 3'
unzipped by DNA Helicase
3' CGACTTTT 5'
-Subsequently a primer (a single stranded RNA segment) is synthesized AT THE 3 PRIME END of the DNA strand, so the primer is  the 5' and the DNA strand is the 3'. ( this is very important)!! This is done by the enzyme DNA/RNA primase.
3' ACTGAAAA 5'
5'TGA-primer

              AAAA 5'
5' CGACTTTT 3'

-Then the enzyme DNA polymerase ( NOT RNA poly, do not get confused) will synthesis the new base sequence starting from the primer end. DNA polymerase can ONLY synthesize the strand in the 5 prime to 3 prime direction. The top strand is called "leading strand".
- The bottom strand however has a problem because it has to be synthesised in the 3 prime to 5 prime direction. as mention before DNA poly. can only do 5-3 prime. What it does instead, it synthesises small fragments called Okazaki fragments backwards, therefore we call this the "lagging strand.
3'            AAAA 5' <---------DNA polymerase cant synthesise 3 prime to 5 prime
5' CGACTTTT 3'   
-Lastly DNA ligase will join all the strands together and replace the RNA primer with the correct nucleotide ( A replaces U).
DNA replication in a nut shell

[gameboy99]

Thanks for the explanation makes sense.

[instax101]

Hey guys,
I was just wondering if any people had the Unit 3 TSSM 2014 Biology Exam Answers as I seem to have misplaced it.

Thanks

[Hayley_turnham]

is the Bey2 gene and OCA2 gene for eye colour linked? They are both on chromosome 15 so does this imply that they are linked?

[blacksanta62]

Yes. Linked genes are alleles which are in close proximity to each other on the same chromosome. Was this something that you just searched on google?

[Hayley_turnham]

Thanks
Yeah I did. google was just confusing me a little bit cause there are so many different genes involved in producing eye colour and they all do different things

[blacksanta62]

There are so many genes and alleles which are involved in the same thing. Some people I know hate dihybrid crosses, lol, I should show them trihybrid crosses . but yeah, things like height are determined by many different genes.

[Hayley_turnham]

hahaha trihybrid crosses are even better :')
okay thanks heaps!!