Two different mutations are identified in a haploid stra...

Question

Two different mutations are identified in a haploid strain of yeast. The first prevents the synthesis of adenine by a nonsense mutation of the ade-1 gene. In this mutation, a base-pair substitution changes a tryptophan codon (UGG) to a stop codon (UGA). The second affects one of several duplicate tRNA genes. This base-pair substitution mutation changes the anticodon sequence of a tRNAᵀʳᵖ from

3′−ACC−5′ to 3′−ACU−5′

Do you consider the first mutation to be a forward mutation or a reversion? Why?

Accepted Answer

Hello everyone and welcome to today's video. So the impact of mutations in an organism may depend on the type of mutation. A specific sequence has undergone. So consider the following M R N A sequence. We have three prime U C U P, five prime, 23 prime C G A five prime. So what type of mutation is illustrated in the given sequence? As answer choice. A we have miss sense mutation as answer choice B we have a nonsense mutation. Answer choice C is a silent mutation and answer choice. These are non synonymous mutation. Now there is something that we need to understand about this change before we jump into our answer choices first, the M R N A, once it arrives to the ribosome is going to be red in the P five prime to three prime direction. So we want, if we want to understand the type of mutation that occurred, we need to flip these two M R N A sequences. So the first one is going to be five prime, you see U three prime, but the second one is going to be five prime A G C three prime. This is what we need to do if we want to understand the type of mutation that occurred. So the first one is going to code for sin, but the second one is also going to code for sin. So nothing really happened here. We still have the same amino acid. And when this happens, we say, or it is known as a silent mutation because there's really no effect on the protein from the mutation that occurred. And this is represented by answer choice CS mutation. I really hope this helped and I hope to see you on the next one.

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