Genetics Answers

The following fragments were obtained after digestion of a sequence using restriction enzymes: 5.3 kb, 2.1 kb, 6.8 kb, 3.6 kb, 1.1 kb, 2.2 kb. Order the fragments, moving from the fastest migration to the slowest migration on a gel. Which two fragments may be difficult to isolate on a gel? Why? Sketch the resulting gel after running the fragments on it. Assume that the fragments were all run in one lane. Label the positions of the positive and negative electrodes. 

Tay-Sachs disease is an inherited disease that is caused by a recessive allele. If a man and his wife, who are both carriers, have three children, what is the probability of each of the following? Show your calculations and give your answers as fractions.

a) All their three children do not have the disease.

d) At least one child is phenotypically normal without the disease.

b) One or more of their three children have Tay-Sachs disease.

c) All three children have the Tay-Sachs disease.

1. You are a Geneticist employed by Thato Biotech Pty Ltd in a criminal case, which could not be solved due to the integrity of DNA used as evidence. You are requested to ascertain the integrity of DNA evidence. You decided to resuspend the purified DNA in a volume of 100uL of double-distilled nuclease-free sterile water. You then diluted 10uL of the DNA sample to a total volume of 100uL with water quality for spectrophotometric analyses. On measuring the absorbance of this diluted sample at 230, 260, and 280nm she obtained the following readings:

A280nm= 0.494; A260nm = 0.364; A230nm= 0.191

a) What is the DNA concentration of the 100uL aliquot, in 3 significant figures

b) How much total DNA was purified by the procedure?

c) Is this DNA pure? If yes, how do you know? if not, what is the most likely contaminant?

d) if this DNA was contaminated with salts what would you expect in the absorbance readings?

e) If DNA was contaminated with RNA, how would you purify your DNA?

If height were entirely genetically controlled, what concordance would you expect between monozygotic twin pairs?

A cross was made between pure breeding plants differing in two characters (colour and shape of seed) and the progenies were intercrossed to produce F2 population. Four types of phenotypes; yellow round (1200), yellow wrinkled (386), green round (372) and green wrinkled (144) were observed in F2. Use the chi-square test to determine if these results are due to independent assortment 

explain why mismatch repair is the more important for the accuracy of DNA Replication

Discuss what happens when an individual with 17 chromosomes mates with an individual of the same species with 16 chromosomes.

Can Nonsense mutation be reversed by hydroxylamine? Why or why not?