Question

Help please? I'll fan and medal :)


1. Which of the following sequences is an example of a point mutation of the DNA sequence -A-A-G-T-G-C-?

*-A-A-A-T-G-C-
*-A-A-G-U-G-C-
*-G-T-A-G-A-A-C-
*-A-A-G-G-T-C-

I don't get this question like at all, but my best guess is the last choice, even though I'm sure it's wrong. Any help is appreciated :)

Answer 1

You have
A A G T G C
as your given sequence
if you have point mutation in this sequence
you would expect ONE OF THE LETTERs/bases to be DIFFERENT from what is your original sequence
meaning if your original one is
AAGTGC
then your point mutated would be
ACGTGC
if you take close look, you can see that second A from your original sequence is replaced by C here and the rest is exactly same

Answer 2

notice one more thing. the talk in the question is about DNA
so U (Uracil) is NOT one of DNA bases
it belongs to RNA bases
so you can straightaway eliminate the choice having U in the sequence

Answer 3

also in notice number of bases given in your sequence
if you are given 6 bases as it is in this q
then mutation has to occur WITHIN these 6 bases
meaning ONE of the 6 bases is to be replaced by other base, in other words mutated

addition to these 6 bases
or removal of one of the 6 bases is a different type of mutation
its called 'frameshift mutation'
if base is removed 'framshift delition'
if base/s added 'framshift addition'