Lily12333
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#1
Report Thread starter 3 years ago
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Hi saw this on the spec don't quite understand
explain simply how the structure of DNA affects the protein made
• describe how genetic variants may influence phenotype: a) in coding
DNA by altering the activity of a protein: and b) in non-coding DNA by
altering how genes are expressed.
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macpatgh-Sheldon
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#2
Report 3 years ago
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explain simply how the structure of DNA affects the protein made
ANS: you can talk about the four nitrogen bases (A, T, C & G), (+ about double helix) which base binds which, triplet code, its copying onto mRNA (transcription), then translation (brief mention of specific tRNA and degenerate nature of code) i.e. protein synthesis.

• describe how genetic variants may influence phenotype: a) in coding
DNA by altering the activity of a protein:
Read up how changing one nitrogen base (by deletion, addition or by substitution with the wrong base) can change the triplet code, and how this will make a different protein with different amino acid sequence - this can change phenotype (the physical features of a living thing e.g. hair colour OR short/long tail of a bird OR size of peas, etc by changing an enzyme (you know these are proteins) or a structural protein (one that makes up a part of the body).

and b) in non-coding DNA by
altering how genes are expressed.

Non-coding DNA is the part of the chain that starts or stops the reading of the code on DNA - it can be triggered on or off by different proteins (called transcription factors) so that a protein [that is coded for by the DNA) is either made OR not made, so a certain action may or may not take place (due to enzyme being made or not made, respectively).

I have tried to keep this simple for GCSE level, but if still struggling, ask away!

M
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