Edexcel GCE Biology Unit 4 6BI04 June 2013

Describe how does the sequence of bases in a DNA molecule would be used to form the primary structure of a protein?

Hi guys just a last minute Q, hope u can help

Basically there's a few questions which I get stuck on such as discuss the validity of such statements for graphs and how to interpret the graph to pick a valid statement etc... Does anyone have any advice on how to go about these Qs and how to interpret the graphs ?? Any help is appreciated :smile:

Reply 282

Sravya

Original post by bubblegummer

Describe how does the sequence of bases in a DNA molecule would be used to form the primary structure of a protein?

1. idea of sequence of bases {forming the
genetic code / determines the amino acid
sequence} ;
2. idea that one triplet codes for an amino
acid;
3. ref to (DNA) acting as a template ;
4. reference to transcription OR detail of
transcription e.g. DNA unzips, mRNA
synthesis ;
5. idea that mRNA moves from nucleus to
cytoplasm / eq ;
6. reference to translation OR detail of
translation e.g. role of ribosome, codonanticodon
interaction ;
7. idea that tRNA carries an amino acid ;
8. ref to formation of peptide bonds between
amino acids ;
9. idea that primary structure is the
{sequence /order / eq} of amino acids ;
10.comment on post-transcriptional
modification of mRNA (between
transcription and translation)e.g. removal
of introns, splicing

Reply 283

Sravya

Original post by MBSSA

Hi guys just a last minute Q, hope u can help

Basically there's a few questions which I get stuck on such as discuss the validity of such statements for graphs and how to interpret the graph to pick a valid statement etc... Does anyone have any advice on how to go about these Qs and how to interpret the graphs ?? Any help is appreciated :smile:

In terms of validility usually the graph doesnt have enough data..also the graph never tells you about any other vairbales effecting it

Reply 284

MBSSA

Thanks!

Posted from TSR Mobile

Reply 285

Helena Kennedy

Difference between validity and reliability ? :smile:

Reply 286

amber109

3

(c) Suggest reasons for each of the following.
(i) DNA polymerase from human sources is not suitable for use in a PCR
machine.
(ii) Species of plants cannot be identified from woody (xylem) material using PCR
and DNA profiling.

(edited 10 years ago)

Reply 287

nukethemaly

OP

11

Original post by amber109

(c) Suggest reasons for each of the following.
(i) DNA polymerase from human sources is not suitable for use in a PCR
machine.
(ii) Species of plants cannot be identified from woody (xylem) material using PCR
and DNA profiling.

i) human sources can't take the extreme temperatures used in the PCR machine since the enzyme denatures
ii) because xylem contains dead cells.

Reply 288

nukethemaly

OP

11

Original post by Helena Kennedy

Difference between validity and reliability ? :smile:

I'm not too certain but validity is how recent the data is and reliability is what the source is and how many repeats etc were done, and when it was peer reviewed did other scientists find the same results etc.

Reply 289

nukethemaly

OP

11

Original post by Sravya

Does anyone have any advice for last minute revising..have done all the past papers twice should i just go through the syllabus?

I would suggest reading through the textbook, and spec, and making a list of all the definitions you find (these are easy marks), and going through ALL the core practicals in depth. Also might be worth practising calculations involving trophic levels etc.

Reply 290

bubblegummer

Original post by amber109

(c) Suggest reasons for each of the following.
(i) DNA polymerase from human sources is not suitable for use in a PCR
machine.
(ii) Species of plants cannot be identified from woody (xylem) material using PCR
and DNA profiling.

(i) DNA polymerase can only function at human temperature of 37 degrees, the temperature in PCR machine is too high and will denature the enzyme.

(ii). xylem vessel is a dead cell and it does not have nucleus and thus no DNA is present so it cannot be detected

Reply 291

bubblegummer

Original post by Sravya

1. idea of sequence of bases {forming the
genetic code / determines the amino acid
sequence} ;
2. idea that one triplet codes for an amino
acid;
3. ref to (DNA) acting as a template ;
4. reference to transcription OR detail of
transcription e.g. DNA unzips, mRNA
synthesis ;
5. idea that mRNA moves from nucleus to
cytoplasm / eq ;
6. reference to translation OR detail of
translation e.g. role of ribosome, codonanticodon
interaction ;
7. idea that tRNA carries an amino acid ;
8. ref to formation of peptide bonds between
amino acids ;
9. idea that primary structure is the
{sequence /order / eq} of amino acids ;
10.comment on post-transcriptional
modification of mRNA (between
transcription and translation)e.g. removal
of introns, splicing

thank you!! :3

Reply 292

anaab.naeem

Looking at the past few papers, me and my friend came up with what we think will come in the paper tomorrow as:
-TB
-Photosynthesis
-Non-specific response
-Possible Gel electrophoresis
-Succession
-Speciation
-Abiotic and Biotic factors

Reply 293

nukethemaly

OP

11

Describe that data can be extrapolated to make predictions, that these are used in models of future global warming, and that these models have limitations. (spec point 19)

Anyone?

Reply 294

bethanyfish

12

Original post by anaab.naeem

Looking at the past few papers, me and my friend came up with what we think will come in the paper tomorrow as:
-TB
-Photosynthesis
-Non-specific response
-Possible Gel electrophoresis
-Succession
-Speciation
-Abiotic and Biotic factors

Non-specific came up spread over a few questions about histamine and introns in January

Reply 295

MarshmallowBob

Is anyone struggling with the time?

Reply 296

Musanna

anyone with the pdf file for cgp rev guide??? :frown:

Reply 297

bubblegummer

i am slightly confused here... Are the introns in the post-transcriptional process removed or spliced? and are exons spliced as well? i thought splicing means joining them together.

Reply 298

MarshmallowBob

Original post by Sravya

CGP book and do all of the past papers again!

The cgp guide doesnt have anything about lymphocytes :s-smilie:

Reply 299

MarshmallowBob

Original post by bubblegummer

i am slightly confused here... Are the introns in the post-transcriptional process removed or spliced? and are exons spliced as well? i thought splicing means joining them together.

Isnt splicing the process by which the introns are removed, and the exons are joined to from an mRNA strand?

Edexcel GCE Biology Unit 4 6BI04 June 2013

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