re the enzymes for the utilization of lactose synthesized? At a crossroads: Poin

Question

re the enzymes for the utilization of lactose synthesized? At a crossroads: Point mutations vs Frameshift mutations Now that we understand the genetic code and how proteins are made, we are prepared to better understand how mutations can have an effect on normal cell processes. While there are other types of mutations, we will concern ourselves with the two most common-point shift mutations and frameshift mutations. (1) What is a point mutation? (2) Using the genetic code and tryptophan and serine as examples, explain how a point mutation in the DNA could have a dramatic effect on the sequence of a protein, or may not have an effect on the sequence of a protein at all, (3) What is a frameshift mutation? (4) Which is more likely to have a significant effect on the synthesis of a protein, a single point mutation or a single frameshift mutation within the coding sequence? Why? Page 6 of 6 1278 words English (US) : : 20 F6 esc F1 F2 F3 F4 FS

Explanation / Answer

1)Point mutation- In point mutation, in a DNA sequence a single nucleotide will change. This can be a deletion or an insertion or change of a single nucleotide.

2)Lets take the example of serine amino acid.

serine (UCA)- UCU (serine)

here the last nucleotide base is changed, but the amino acid remain the same. This will call a silent mutation , where the single nucleotide changes have no effect on protein.

UCA (ser)-CCA (proline)

UGG (tryp)-UCG (serine)

here, UCA is changed by a single nucleotide change U to C and the amino acid serine is changed to proline. This is an example of misssense point mutation. Whereas, a single nucleotide change of G to C in tryptophan will make serine.

UCA ( Ser)-UAA (stop)

UGG (tryp)-UAG (stop)

here amino acid serine is changed to stop codon by changing a nucleotide C to A. Tryptophan amino acid is changd to stop codon by replacement of G nucleotide with A.

3)Frameshift mutation- During frameshift mutation, when there will be change by a single nucleotide deletion or addition in DNA sequence it will change the way how we are reading frame of the sequence.

for eg. if we take a DNA sequence- CGG CAA GTT

                        amino acid sequence- arginine-glutamine-valine

now , if there is one T nucleotide is added in middle of the sequence

                                                      CGG T CAA GTT

it will change the reading frame to -CGG TCA AGT T

the amino acid now will be read as -      arginine-serine-serine          

this way frame shift mutation will change the reading frame as well as how the amino acids are read.

4) a point mutation usually will change a partcular amino acid. But a frameshift mutation will produce alternative reading frame of the DNA. So, a frameshift mutation will have more significant effect on how a protein is synthesizing.

Related Questions

Navigate

• Browse (All)
• Browse R
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.