Genetics Answers

Which of these triplets represents the meaningless codon,illegible or final and does not carry information about any amino acid? 1) UAC  2) UCA  3)UAG  4)UUA

How many chromosomes are present in the “abnormal” karyotype: _

In pea plants, yellow seeds (Y) are dominant over green seeds (y), and rounded peas (R) are dominant over wrinkled peas (r).

Cross a plant that is heterozygous for both traits with a plant that is homozygous recessive for both traits. Draw a Punnet Square to show all possible offspring and determine the genotypic and phenotypic ratios.

A boy with colour blindness, has a mother with normal colour vision and a father with colour blindness. Did the boy inherit the gene for colour blindness from his mother or his father? Explain your answer to question 2a by using a Punnett square to identify the source of the colour blindness gene that was passed on to this boy.

Explain this type of heredity.

How the trp operon is 1) not expressed when trp concentrations are high; and 2) attenuated differently in the presence and absence of trp.

How many different kinds of F1 gametes, F2 genotypes, and F2 phenotypes would be expected from the following crosses:

(a) AA  X aa; 

(b) AA BB X aa bb;

(c) AA BB CC X aa bb cc?

(d) What general formulas are suggested by these answers?