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Author Topic: VCE Biology Question Thread  (Read 3570919 times)  Share 

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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #12990 on: September 24, 2020, 10:40:07 am »
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Hi Guys!!!

In a ACED 2018 Exam in multiple choice it asks During translation:
and the answer is The ribosome reads mRNA 5’ to 3’. I didn’t pick this answer because although I know mRNA is 5‘ to 3’ I didn’t know ribosomes can read?

Also is simple diffusion slower than active transport? Thanks :)

EDIT: didn’t wanna double post, but in transcription is it necessary to say that “DNA molecule unwinds and is separated” and that “complementary RNA bases are added to a new molecule of mRNA”? I never say this in my answer but this company exam does......what’s vcaas accepted definition?

Is the repressor  protein in lac operon a transcriptional factor?
« Last Edit: September 24, 2020, 11:37:59 am by Coolgalbornin03Lo »
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12991 on: September 24, 2020, 11:26:05 am »
+2
Hi Guys!!!

In a ACED 2018 Exam in multiple choice it asks During translation:
and the answer is The ribosome reads mRNA 5’ to 3’. I didn’t pick this answer because although I know mRNA is 5‘ to 3’ I didn’t know ribosomes can read?
Yeah ribosomes read the strand from 5' to 3' in codons. So the ribosome reads codon by codon, and then a tRNA with a complementary anticodon come and bring a corresponding amino acid.

Also is simple diffusion slower than active transport? Thanks :)
I would think that it's faster as it doesn't require energy and it is a natural movement of a mass of molecules
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darkz

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Re: VCE Biology Question Thread
« Reply #12992 on: September 24, 2020, 11:50:19 am »
+5
Also is simple diffusion slower than active transport? Thanks :)

Yep, active transport would be faster than simple diffusion. If you think about it, active transport is forcing molecules into another compartment (e.g. you throwing a ball into another room) whereas simple diffusion is simply just flowing slowly into another compartment, also with bidirectional movement (e.g. a ball slowly rolling into another room).

Edit: well actually thinking about it, would depend on a variety of factors e.g. concentration of solute we're considering etc. e.g. at high concentrations simple diffusion might be faster since active transport would become saturated?

EDIT: didn’t wanna double post, but in transcription is it necessary to say that “DNA molecule unwinds and is separated” and that “complementary RNA bases are added to a new molecule of mRNA”? I never say this in my answer but this company exam does......what’s vcaas accepted definition?

Personally, I'd include it as at the end of the day, it's all about minimising risk.

Is the repressor  protein in lac operon a transcriptional factor?

Yes, any factor which modifies the rate or functioning of transcription would be termed a transriptional factor.
« Last Edit: September 24, 2020, 11:56:08 am by darkz »
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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #12993 on: September 24, 2020, 02:09:13 pm »
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Thanks darkz !!

With deviant cell behaviour and cancer- does the cell become immortal before accumulating mutations or does the cell accumulate mutations before becoming immortal?
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darkz

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Re: VCE Biology Question Thread
« Reply #12994 on: September 24, 2020, 02:20:43 pm »
+2
Thanks darkz !!

With deviant cell behaviour and cancer- does the cell become immortal before accumulating mutations or does the cell accumulate mutations before becoming immortal?

The cell would accumulate mutations before becoming immortal i.e. mutations in let's say, the gene controlling for the production of apoptosis initiating factors/receptors could lead to immortality.
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12995 on: September 24, 2020, 02:45:57 pm »
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Heyyy! Do we need to mention the direction in which RNA polymerase moves during transcription? Is it 3' to 5' or 5' to 3'? Different sources say different things!
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-Lilac-

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Re: VCE Biology Question Thread
« Reply #12996 on: September 24, 2020, 03:13:08 pm »
+1
Heyyy! Do we need to mention the direction in which RNA polymerase moves during transcription? Is it 3' to 5' or 5' to 3'? Different sources say different things!

RNA polymerase moves from the 3' end of the template towards the 5' end. I don't think you need to specify that exactly, but make sure to mention that the complementary strand is synthesized in the 5' --> 3' direction (which itself implies that RNA pol itself must be moving 3'-->5'). 
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #12997 on: September 24, 2020, 03:21:32 pm »
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Thank you! Why do primers always bind to the 3' end?
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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #12998 on: September 24, 2020, 03:37:15 pm »
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With hardy Weinberg how do you remember that p is dominant and q is recessive

Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #12999 on: September 24, 2020, 03:42:02 pm »
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Thank you! Why do primers always bind to the 3' end?

I thought they bind either side of the gene of interest? As in one on the 3 prime end of one strand and on the 3 prime end of another strand? Because before anneal stage the DNA has disassociates  into single strands?

Maybe it’s because the template strand is 3’ to 5’?

EDIT: since you said primers I assumed we were talking about PCR, but I looked back at the previous comments and You were talking About transcription before. If this is still transcription,, there’s no primers and RNA polymerase reads the template strand 3’ to 5’ because the template strand is 3’ to 5’, and as a result pre-mRNA is complementary 5’-3’.


« Last Edit: September 24, 2020, 03:47:11 pm by Coolgalbornin03Lo »
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homeworkisapotato

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Re: VCE Biology Question Thread
« Reply #13000 on: September 24, 2020, 03:52:27 pm »
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I thought they bind either side of the gene of interest? As in one on the 3 prime end of one strand and on the 3 prime end of another strand? Because before anneal stage the DNA has disassociates  into single strands?

Maybe it’s because the template strand is 3’ to 5’?

EDIT: since you said primers I assumed we were talking about PCR, but I looked back at the previous comments and You were talking About transcription before. If this is still transcription,, there’s no primers and RNA polymerase reads the template strand 3’ to 5’ because the template strand is 3’ to 5’, and as a result pre-mRNA is complementary 5’-3’.

Thank you! I was talking about PCR sorry for not clarifying
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-Lilac-

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Re: VCE Biology Question Thread
« Reply #13001 on: September 24, 2020, 04:06:30 pm »
+3
I thought they bind either side of the gene of interest? As in one on the 3 prime end of one strand and on the 3 prime end of another strand? Because before anneal stage the DNA has disassociates  into single strands?

Maybe it’s because the template strand is 3’ to 5’?

EDIT: since you said primers I assumed we were talking about PCR, but I looked back at the previous comments and You were talking About transcription before. If this is still transcription,, there’s no primers and RNA polymerase reads the template strand 3’ to 5’ because the template strand is 3’ to 5’, and as a result pre-mRNA is complementary 5’-3’.

Yep, PCR uses forward and reverse primers. The primers are on the 3' ends of the strands as DNA polymerase synthesizes a new strand in the 5'–3' direction.

Transcription does not require the use of primers as RNA polymerase can initiate RNA synthesis without them. In contrast, DNA polymerase cannot initiate DNA synthesis without a primer as it requires a free 3′-OH group to extend from.

With hardy Weinberg how do you remember that p is dominant and q is recessive


I used to remember this by thinking that since q is a more rare letter than p it means recessive which is also rarer.
« Last Edit: September 24, 2020, 04:11:10 pm by -Lilac- »
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Re: VCE Biology Question Thread
« Reply #13002 on: September 24, 2020, 04:29:58 pm »
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does anyone here know a good way of remembering/ explaining 3' and 5' strands like i relearned it a hundred times but i keep mixing them up. which way is downstream? do i even need to know?
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-Lilac-

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Re: VCE Biology Question Thread
« Reply #13003 on: September 24, 2020, 09:13:52 pm »
+5
does anyone here know a good way of remembering/ explaining 3' and 5' strands like i relearned it a hundred times but i keep mixing them up. which way is downstream? do i even need to know?


Is there anything specific you are having problems with? Transcription, translation or replication etc???

As you know, the DNA strands run anti-parallel to each other.

DNA replication always results in daughter strand synthesis in the 5' - 3' direction. The lagging strand is also synthesized discontinuously as it is formed away from the replication fork.

5' AAATTTCCC 3' (leading strand)
      <---------- 5'
5' ----> 5' ---->
3' TTTAAAGGG 5' (lagging strand)

Transcription by RNA pol will also occur in the 5' - 3' direction.

5' AAATTTCCC 3' (coding strand)
5' -------------> (mRNA)
3' TTTAAAGGG 5' (template strand)

mRNA is then read by the ribosome from the 5' to the 3'.

Regarding upstream and downstream, this usually refers to where a point in the sequence is relative to a gene on the coding strand. I don't think you need to know this for VCE though.

5' AAATTTCCC 3' (coding strand)
3' TTTAAAGGG 5' (template strand)

For example, let's say our gene sequence is ATTTC (bold). Then we can say that the AA towards the 5' end is upstream of the gene and the CC towards the 3' end is downstream of the gene. You will often hear promotors referred to as upstream, as they are located before the coding sequences towards the 5' end of the coding strand.
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Coolgalbornin03Lo

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Re: VCE Biology Question Thread
« Reply #13004 on: September 24, 2020, 10:23:05 pm »
+3
does anyone here know a good way of remembering/ explaining 3' and 5' strands like i relearned it a hundred times but i keep mixing them up. which way is downstream? do i even need to know?

Just remember that mRNA is 5’ to 3’. It’s the key to everything. By remembering only that:

We know the template strand is 3’ to 5’ as RNA polymerase reads it and mRNA is complementary.

Coding is 5’ to 3’ bc you know opposite of template.

And the anticodons = 3’ to 5’ like the template strand :)
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