Exam 14: Translation and Proteins

Regarding the protein structure, how are β-pleated sheets arranged and stabilized?

Which protein class directly controls many of the metabolic reactions within a cell?

Assume that a base addition occurs early in the coding region of a gene. Is the protein product of this gene expected to have more or fewer altered amino acids compared with the original gene with a base deletion late in the coding region?

Describe the conceptual basis for constructing biochemical pathways using nutrient supplement experiments with Neurospora.

The following table presents the effect of different media on the growth response of tryptophan mutations in Salmonella typhimurium (+ = growth, - = no growth).

		Medium Supplemented with
Strain	No Supplement	IGP	AA	IN	TRY
trp-8	-	+	+	+	+
trp-2	-	+	-	+	+
trp-3	-	-	-	+	+
trp-1	-	-	-	-	+

(a) Construct the biochemical pathway for the compounds IGP, AA, IN, and TRY based on these data. (b) Place strains of bacteria (mutations) in the appropriate steps in the pathway. (c) In bacteria it is often possible to make partial diploid strains. Assume that a diploid strain was made containing the complete genomes of the trp-2 and trp-1 strains. Would this diploid strain be able to grow on the unsupplemented medium? Explain your answer.

The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. In comparing the normal β chain with the β chain in sickle cell hemoglobin, what alteration is one likely to find?

Describe each of the following parameters that relate to the structure and function of tRNA: (a) four functional domains (b) Wobble hypothesis

A protein is 300 amino acids long. Which of the following could be the number of nucleotides in the section of DNA that codes for this protein? (Remember: DNA is double-stranded.)

The ribonucleic acid components known to exist in eukaryotic ribosomes are the following: 5.8S, 18S, 28S, and 5S.

Knowing that the base sequence of any given messenger RNA is responsible for precisely ordering the amino acids in a respective protein, present two mechanisms by which intrinsic properties of mRNA may regulate the "net output" of a given gene.

In what ways do the amino acid side chains interact to influence protein function?

Nutritional mutants in Neurospora can be "cured" by treating the medium with substances in the defective metabolic pathway. What determines whether the mutant strain (auxotroph) is "cured" by a particular substance?

Electrophoretic separation of HbA from HbS is based on a difference in their ________.

The primary structure of a protein is composed of the sequence of amino acids in that protein.

The one-gene:one-enzyme hypothesis emerged from work on which two organisms?

Describe the basic structure of normal adult hemoglobin and the abnormality observed in sickle-cell hemoglobin.

What is the structure of fetal hemoglobin (HbF)?

Below are several phenomena relating to protein structure. Clearly describe each phenomenon, the conditions under which each occurs, and the probable influence each has on protein structure. (a) hydrophobic interactions (b) hydrogen bonds (c) disulfide bridges

Which class of protein functions primarily by lowering the energy of activation during a reaction?

The primary structure of a protein is determined by ________.