Genetics Answers

Deduce and explain the effects of mutations:

a) in the operator, so that the repressor is no longer able to bind.

b) in lacI, so that the repressor is no longer synthesized.

c) in the promoter, so that RNA polymerase no longer binds.

d) in lacI, so that the repressor no longer binds to lactose.

e) in lacY that causes transcription to terminate in the middle of the gene.

f) location unknown, which prevents the lac mRNA from being degraded. 

Why can't normal hydrogen bonding with nitrogenous bases of DNA occur when the molecule is in duplex/helix form?

The ability to taste a bitter chemical, phenylthiocarbamide (PTC), is

due to a dominant gene. Use T and t to symbolize the two alleles of this gene.

A lawyer sets out to prove that a child with type A blood is the son of a man with type B blood and a mother with type AB blood. Determine if it is possible for the man to be the father. Is he definitely the father?

a. Test cross method

b. Genotypic Ratio

c. Phenotypic ratio

A) A cross was made between pure breeding plants differing in two  

characters (colour and shape of seed) and the progenies were inter-crossed  

to produce F2 population. Four types of phenotypes; yellow round (1108),  

yellow wrinkled (382), green round (366) and green wrinkled (140) were  

observed in F2. Use the chi-square test to determine if these results are  

due to independent assortment.

B) Explain prophase and metaphase stages of mitosis

Choose the correct completion.

The correct development of the sense of smell is controlled by the action of two genes, A and M; the absence of at least one dominant allele for each of the two genes causes insensitivity to odors in the unborn child. What is the probability that the first child of the following couple will be affected by this disorder?

AaMm X AAmm

to. 0%

b. 12.5% c. 25% d. 50%

In garden peas, green pod color is dominant over yellow pods. Also, round seed shape is dominant over wrinkled seed. Cross-fertilization was done between a pea that is homozygous dominant for pod color with heterozygous round shape and another pea that is heterozygous for both pod color and seed shape. Determine the genotypic ratio and phenotypic ratio of the offspring.

 Instruction: Analyze each genetic problem. Answer what is asked for. Show complete solution.

1. A cross between a black cat and a tan cat results in a tabby A tabby cat is crossed with a tan cat.

• What is the pattern of inheritance in this example? (1 point)
• What ratio of the offspring will have tabby fur? Tan fur? Black fur? (3 points answer; 4 points Punnett square)

1. In the n the early 1940s, famed entertainer Charlie Chaplin was taken to court in a paternity case brought by his former protege, Joan Berry. Berry was 23 and Chaplin 54, and she alleged that he was the father of her newborn baby, Carol Ann. Charlie Chaplin’s blood type was already on record as type AB. The mother of the child had type A and her child had type O

• Complete a Punnett square for the possible cross of Charlie and the (4 points)
• The judge ruled in favor of the mother and ordered Charlie Chaplin to pay child support costs of the child. Was the judge correct in his decision based on blood typing evidence? Explain why or why (3 points)

Genetic cross for two grey mice where the offspring are grey,white and black

PART 1: Read and analyze the following genetic problem. Answer what is being asked. Show complete solution (Genotypes of P, Punnet Square and GR, PR). (10 points)

Criteria:

Genotypes of P = 2 pts 

Punnet Square = 4 pts 

GR, PR = 4 pts

TOTAL = 10 pts

• In garden peas, green pod color is dominant over yellow pods. Also, round seed shape is dominant over wrinkled seed. Cross-fertilization was done between a pea that is homozygous dominant for pod color with heterozygous round shape and another pea that is heterozygous for both pod color and seed shape. Determine the genotypic ratio and phenotypic ratio of the offspring.