Urgent question

Hi there
I have a really quick urgent question

  • When describing unlinked genes do we say that they are genes far apart on the same chromosome or different chromosomes?
    Also just to confirm two chromatids make up one chromosomes right?

  • The question asked was to discuss the advantages of multiple alleles?

My answer: Multiple alleles are advantageous to a population because it increases the combination of alleles that can appear together in a gamete. Multiple alleles also increase the variety of recombinants in the population. These two factors increase genetic variation in a population. Having multiple alleles also reduces the chance that two harmful recessive alleles will come together so if inbreeding does occurs multiple alleles reduce the chance of harmful genetic conditions occurring.

Marking schueldes : The advantages of multiple alleles within a species means more phenotypes are expressed and therefore more different
phenotypes can respond to natural selection pressures and
increases the chances of survival of species (especially if
environmental conditions change)

To get E for this question induvial must discusses advantages of multiple
alleles to a species.
What grade would my answer get?
P.S this is from the 2019 Genetic Variation question Q3 d

Hi there

There seems to be a slight confusion here.
Unlinked genes are genes that are NOT on the same chromosome.

Linked genes are genes that are found on the SAME chromosome.
If the genes are FAR apart, they are more likely to experience a crossing over event and thus go through recombination.
If the genes are close, they are less likely to get separated via crossing over, thus they get INHERITED together (hence, decreasing genetic diversity in a population).

However, (you don’t need to know this far - uni level stuff) since recombination events are calculated as a probability event, if genes go through a recombination event, unless we have a large enough sample size to calculate the observed frequency, there are two possibilities:

  • the genes are LINKED, but FAR APART … hence they get separated via CO
  • the genes are UNLINKED.

Not quite. A chromatid is a chromosome that has gone through DNA replication. (Therefore, each half is an exact copy)

Your answer would most likely be awarded an M (if there there was an M opportunity somewhere there. For the E, it would seem that you need to link your discussion to the expression of the phenotype allowing the species to better respond to a changing environment (because there is a chance some/few of the individuals would have a variation of an adaptation that helps them with the changed environment), hence giving the species (or population) and overall survival advantage.

Your answer indicates you are on the right track!
On a side note, every time you see a Natural Selection question, don’t forget to mention the [adaptation] provides the individual with a survival advantage, hence it will be more likely to survive, reproduce and “pass on that beneficial alleles”. Overall increasing the frequency of that beneficial allele.

Hope that helps!