Exam 13: Translation and Proteins

Early in the 1900s,Sir Archibald Garrod studied a number of metabolic defects in humans.One particular disorder involved the inability to metabolize homogentisic acid.What is the name of this disorder?

Studies of Neurospora led to the ________ statement,whereas studies of human hemoglobin led to the ________ statement.

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

What are polyribosomes?

Proteins are composed of strings of nucleotides connected by 5'-3' phosphodiester bonds.

Considering the types of side chains on amino acids and their relationship to protein structure,where are the amino acids with hydrophobic side chains most likely to be located?

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

Three major types of RNAs are mRNA,rRNA,and tRNA.For each of the conditions below,predict the consequences in terms of the population of proteins being synthesized in a particular cell.What qualitative and quantitative changes,if any,are expected in the individual protein involved (if one is involved)and in the population of proteins in this cell?

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

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.

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.)

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

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.

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

Below is a set of experimental results relating the growth (+)of Neurospora on several media (MM = minimal medium).Based on the information provided,present the biochemical pathway and the locations of the metabolic blocks. $\text { Strain }$ $\quad$$\quad$$\quad$$\quad$$\quad$ $\text { Medium }$ + + s111 - + + t60 + + + s211 - - +

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

The following table presents the effect of different media on the growth response of tryptophan mutations in Salmonella typhimurium (+ = growth,- = no growth). $\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\text { Medium. Supplemented with }$ trp-8 trp-2 trp-3 trp-1 - - - - IGP AA IN TRY + + + + + - + + - - + + - - - + (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.

Much has been learned about the relationship between genes and gene products through the use of the mold Neurospora.What specific attributes make Neurospora a good organism for such studies?

By their experimentation using the Neurospora fungus,Beadle and Tatum were able to propose the far-reaching hypothesis that ________.