Question

Using the chart, which of the following point mutations will cause the most harmful effect on an individual?

IMAGE LINK:
https://www.connexus.com/content/media/507563-892011-13429-PM-509994576.png

A. The sequence reads AUU; a change in the second base from U to C
B. The sequence reads CGA; a change in the first base from C to A
C. The sequence reads UGU; a change in the third base from U to A
D. The sequence reads UUA; a change in the first base from U to C and a change in the third base from A to G

Answer 1

Look at what each base corresponds to on the chart. For instance, D shows that UUA matches with Leucine and changing the first base from U to C makes it CUA which is also Leucine! So if this point mutation occurred, the same exact protein would be produced from the sequence! So you know that D is wrong, see if you can eliminate 2 more by the same way.

Answer 2

is it B? A ends up on threonine, B lands on arginine and C lands on stop.

Answer 3

Nope, I think you're reading it wrong. The letters on the sides help you find what code you're looking for easier. So the left column says that everything to the right of it starts with that letter, for instance.

CGA codes for Arginine and only Arginine. But, there is more than one way to code for Arginine, such as AGA also codes for Arginine. DNA is read out in sets of 3 that code for 1 amino acid.

Look at the page and notice how in the first column you have Phenylalanine listed twice next to UUU and UUC? See how both of those three letter codes produce the exact same amino acid? This is part of why DNA is so good at what it does. If there was a mess up in the DNA code of UUU that changed it to UUC, your body would still code for the same amino acid!

But what the hell are amino acids? They're the building blocks of proteins which make up your body. So if the code changed and started making different things, that's where mutants come from! Hopefully that explains it a little better, I can try to help you more if you need it.

Answer 4

C. The sequence reads UGU; a change in the third base from U to A

cytosine to stop
pre-termination of polypeptide

Answer 5

Exactly. Putting in a different amino acid in can mess up the protein, but completely cutting the chain of amino acids in mid-production can cause a much larger loss of information.

Answer 6

Thanks so much, I've never been good at biology so thanks for explaining it to me!! :)

Answer 7

So it's C where it stops. That's bad?