5.4: Non-Mendelian Genetics

Question 1

What are linked genes? How are the predicted ratios different in linked genes?

Answer 1

Genes that are adjacent or close to each other on the same chromosome so meiosis crossing over wont separate them. (Opposite of independent assortment). This means that they will be 1:1:2 as opposed to 1:3:3:9

Question 2

If the recombination frequency is 15%, how far apart are the two genes?

Answer 2

Recombination frequency-lower numbers means that they are closer together. (above 50% means that they are not linked genes).

Question 3

If a male is affected with a sex-linked trait with unaffected parents, what are the genotypes of the parents?

Answer 3

The mother had an X linked trait.

Question 4

What type of sex-linked cross would result in a 2 normal females, 1 normal male, and 1 affected male?

Answer 4

The mother had one X linked recessive allele

Question 5

What is a polygenic trait?

Answer 5

When two or more genes can work together affect a single phenotypic characteristic (skin color).

Question 6

What organelles contain DNA? How does this support the endosymbiotic theory?

Answer 6

Mitochondria and plastids contain DNA. This supports the theory that prokaryotic cells originally were engulfed and were ancestors of the mitochondria.

Question 7

What would you look for in a pedigree to identify if the trait is autosomal or sex-linked?

Answer 7

If there are more males affected, then it can be sex linked. Also, half shaded female means they are carriers of a recessive sex linked allele.

Question 8

If a trait is found on the DNA in a chloroplast, what is the mode of inheritance?

Answer 8

Through the mother.

Question 9

What would you look for in a pedigree to identify if the trait is due to non-nuclear inheritance?

Answer 9

All would inherit the disease since it is located in the cell itself, so it does not matter the alleles present.