1) When 10ug of an enzyme (MW 50,000) is added to a reaction mixture containing its substrate at a concentration one hundred times the Km, it catalyzes the conversion of 75umol of substrate into product in 3 min. What is the enzyme's turnover number?

2) You want to load 15g of protein in 10L into one of the 12% polyacrylamide gel well. The protein needs to be in 1X buffer and in a total volume of 0.100 ml. You are given a 4.5 mg/ml protein solution, a 20X sample buffer, and distilled water. How much of each would you mix together to make required volume?

3) The Km of an enzyme of an enzyme-catalyzed reaction is 6.5uM. What substrate concentration will be required to obtain 45% of Vmax for this enzyme?

Indicators are weak acids. Explain why we don’t see a buffer curve for them in the titration of the acids? What is it that makes methyl orange different from phenolphthalein (as an indicator)? How would one decide on an indicator to use for a given titration?

Discuss the following enzymes: hexokinase, pyruvate dehydrogenase, ATP synthase and phosphofructokinase.

-How do these enzymes interact with their substrates and catalyze reactions?

-What is unique about each type of enzyme and why are each of the enzymes suited to the specific reactions which they catalyze including major points of regulation (enzyme catalysis, the mechanism of interaction of enzymes with their substrates and the effect of regulators/inhibitors on enzymes)?

-What is the organization of the active site for each enzyme? Are any of these enzymes considered cellular motors? Why?

50 units of protein A are required per cell to establish a wild-type phenotype. A single wild-type allele of gene A produces 40 units of enzyme per cell. Which of the following statements is true regarding the wild type allele. Select ALL that apply.

The AseI restriction enzyme recognizes the sequence ATTAAT. Which of the following prokaryotic genomes will on average yield thelargest fragments after cutting with this enzyme?

Place the events listed below in the correct chronological order for protein synthesis.

A protein is produced

Genome in nucleus

Ribosome adds an amino acid to a growing amino acid chain

Gene copied as mRNA

tRNA anticodon binds to mRNA codon

mRNA joins ribosome

A mutation replaces the original amino acid, leucine, with threonine in a large protein. The altered protein still functions, but less efficiently. What amino acid might replace leucine but with less effect on protein functions? What amino acid might replace leucine but with even a worse effect on the how the protein functions?

a) less effect if lysine; worse if alanine

b) less effect if methionine; worse if lysine

c) less effect if methionine; worse if alanine

d) less effect if glutamate; worse if lysine

e) less effect if lysine; worse if methionine

In general, if p is the number of predictor variables and k is the number of groups for the outcome variable in a DA, how many different discriminant functions can be obtained to differentiate among
groups? (This question assumes that the X predictor variables have a determinant that is nonzero; that is, no individual Xi predictor variable can be perfectly predicted from scores on one or more other X
predictor variables.)

The following sequence represents the DNA template strand of a gene.

3′-TAC TGT GTC TCC CAC CGA ACT-5′

nucleotide number 1 21   

a. What is the mRNA transcribed from this sequence?

b. What is the amino acid sequence translated from the mRNA?

c. If there is a transition at nucleotide #7, what is the amino acid sequence?

d. What type of mutation is this (choose from frameshift, missense, nonsense, silent)?

e. If there is a transversion at nucleotide #6, what is the amino acid sequence (start with the original sequence, there is more than 1 correct answer)?

f. What type of mutation is this (choose from frameshift, missense, nonsense, silent)?

g. If there is a transition at nucleotide #10, what is the amino acid sequence (start with the original sequence)?

h. What type of mutation is this (choose from frameshift, missense, nonsense, silent)?