Question

A point mutation can cause: a. A frame shift mutation
b. A missense mutation
c. A nonsense mutation
d. All of the above
e. A and C

Answer 1

A point mutation is when one incorrect nucleotide is substituted for the nucleotide that should be there. For example, in the sequence TTTTT, the incorrect substitution TTATT would be a point mutation...

Answer 2

so its B?

Answer 3

since it would just change which amino acid is coded for

Answer 4

I agree - missense it is. :)

Answer 5

well then what would the frame shift be? is it when the a nucleotide is deleted?

Answer 6

A frame shift is an insertion or a deletion. Look at the three letter (i.e., codon) sentence:

THE RED CAT SAT

Then insert a letter at random (D, second place, first word) (and note that deleting a letter at random would have the same effect) and still chop it up by thee letter blocks:

TDH ERE DCA TSA T

And it's nonsense. That is a frameshift mutation.

Answer 7

ahh okkk... now that makes sense. so frame shift is adding or removing nucleotide not multiples of 3, which will cause a shift. and a missence is just replacing a nucleotide with another one

Answer 8

Exactly. ;)

Answer 9

Actually, the point mutations (i.e., missense mutations) are often relatively benign. Very little if any biologic impact. (Sometimes single point mutations do have a big affect and some classic and very serious diseases result from it).

The reason being that more than one codon codes for the same amino acid - so sometimes there is a mutation but the new code still codes for the same amino acid. Or it does affect which amino goes where, but the new amino acid has no real effect on what the protein actually does.

Whereas insertion/deletion mutations (often called in-del mutations) obviously entirely mess up all the amino acids in the rest of the protein. And are much worse, always result in a non-functioning protein, and much more often cause diseases.

It's interesting stuff. ;)

Answer 10

ooh ok. yea very cool learning about this! thanks anyway!