1 mark bio question please help

please help

wtf what exam board is that on

please help

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4^3
4 Different nitrogenous Bases
3 Codons in each amino acid

Thanks! But wait 4 diff nitrogenous bases and 3 bases in each amino acid --> base 1 can one of 4 diff bases, base 2 can have one of 4 diff bases and base 3 can have 1 of four diff bases so 4 x 4 x4 = 64 right?

Also, can you help with this one too will massively appreciate!! Dont quite understand the wording of the question

Thanks! But wait 4 diff nitrogenous bases and 3 bases in each amino acid --> base 1 can one of 4 diff bases, base 2 can have one of 4 diff bases and base 3 can have 1 of four diff bases so 4 x 4 x4 = 64 right?

Also, can you help with this one too will massively appreciate!! Dont quite understand the wording of the question

The main idea is, you have 64 different codons, so how come you get only 20 amino acids, not 64? Several codons can code for one amino acid and some are stop/start codons.

Thanks! But wait 4 diff nitrogenous bases and 3 bases in each amino acid --> base 1 can one of 4 diff bases, base 2 can have one of 4 diff bases and base 3 can have 1 of four diff bases so 4 x 4 x4 = 64 right?

You’re correct on you 4x4x4=64 that’s jut another way of wording it to get to the same place.

As regards the other 44 combinations, you must think of how the genes work. You’ll need something to start the transcription process such as a start codon and you’ll need one to stop it such as a stop codon.

What you may also know is that there is only one start codon (AUG) which codes for methionine while there are three different stop codons. The reason for this being a further reason for the rest of the seemingly redundant code. In the even of a mutation such of any variety there are a few possibilities. It can shift the reading frame, it can have no effect or it can change the effect. So to have three stop codons ensures the likelihood of a stop codon being read even post mutation.

Moreover, the seemingly redundant code is present as combinations which may also produce varying amino acids. Most amino acids are coded for by a variety of triplet combinations and this increases the likelihood of the correct amino acid being produced even if there is a mutation. Please see attached picture to compound your knowledge.

Thanks! Sure, this makes sense but what I am specifically confused about is their wording of "In theory, this would need only 20 different base combinations." Isn't it meant to be 20 different codon combinations cause base is just a single unit in the codon. There are 20 amino acids so 20 different codons? I understand the rest just the wording of the bold bit doesn't make sense
Could you please kindly lemme know your thoughts?

Thanks a lot!! This make much sense.
but what I am specifically confused about is their wording of "Twenty different amino acids are commonly used for protein synthesis.In theory, this would need only 20 different base combinations." Aren't they meant to say 20 different codon combinations cause base is just a single unit in the codon. There are 20 amino acids so 20 different codons? I understand the rest just the wording of the bold bit doesn't make sense
Could you please kindly lemme know your thoughts?

A codon is a three letter segment of code and as I said, 20 different base combinations means twenty different codons each made of a different combination of bases. So in this case base combinations is synonymous with codon.
EG:
ACT and CGC are two different base combinations

Essentially no they have worded it fine. A codon is a triplet if bases however it is the bases themselves that vary not the codons.

For example if I was to say (using the picture above as reference) that UCU coded for serine I would be saying that the single codon UCU codes for serine OR the combination of bases UCU codes for serine. It is the collective organisation of the bases which varies to produce the amino acid not the codon. The codon is simply a result of the triplet complex.

There are 20 individual codons however 20 different codon combinations would result in a different overall protein. 20 different base combinations are what result in the production of one single amino acid which varies.

Say our chain was as so:

Met-Ser-Ser-Asp-Ala-Val-Gly-Gly-UGA

To change the codons of say our second amino acid we could still have serine. If we changed the base however it could result in production of a different amino acid.

Ohhhhhh right thank you so much for making this clear!!!!