If a mistake is made during the DNA replication of the protein insulin, how many molecules of insulin are?

Question

likely to contain an error.

All the molecules of insulin produced by one cell. Or All the molecules of insulin produced by the daughter cells that contain the mutation.

Answer 1

Your instructor doesn't know how to write questions.

But I know you can't get away with telling him or her this.

To answer this you need to know two things.

There are two copies of the insulin gene. If there's A mistake, then it's obviously just in one, as replication of these two genes is independent (on different chromosomes, even). Below I'll call these 'copy 1' and 'copy 2'.

When a replication mistake is made, one new copy is normal, one is mutant.

Here are the replicated DNA strands, with a * representing the error.

copy 1a -------------------
copy 1b -------------------

copy 2a -----------------
copy 2b ----------*------

Each cell gets, randomly divvied up, one of copy 1 and one of copy 2. So, one cell has two normal copies of insulin. The other gets a normal copy and an abnormal copy.

As another answerer said, a mutation doesn't necessarily mean a change to the protien. But let's assume that it does, to placate your instructor.

One half of the insulin molecules in one of the two daughter cells contains an error.

Answer 2

Well, this really depends. First, the copy of the gene from the other parent will be ok, so both those answers are off by 50%.

Second, a mutation in a DNA codon doesn't always change the amino acid it codes for. This is due to the redundancy of the genetic code: http://en.wikipedia.org/wiki/Codon#Degeneracy_of_the_genetic_code

Answer 3

All the insulin molecules would be defective from a cell with the defective insulin gene.