Deck 13: Translation and Proteins

Question 1

The secondary structure of a protein includes _.

A) gamma and delta
B) disulfide bridges
C) hydrophobic clusters
D) alpha and gamma
E) a -helix and fi -pleated sheet

Answer 1

E

Question 2

Draw and label the spatial and polarity relationships among the following translational components: ribosome (small and large subunits), growing polypeptide chains, amino acid attachment to tRNA, mRNA, codon, and anticodon.

Answer 2

Question 3

Side groups of amino acids are typically classified under which of the following?

A) primary, secondary
B) linear, circular
C) alpha, omega
D) long, short
E) polar, nonpolar

Answer 3

E

Question 4

During translation, which triplets signal chain termination?

Question 5

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?

Question 6

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

A) several different enzymes may be involved in the same step in a biochemical pathway
B) the role of a specific gene is to produce a specific enzyme
C) genetic recombination occurred in Neurospora
D) prototrophs will grow only if provided with nutritional supplements
E) more than one codon can specify a given amino acid

Question 7

The primary structure of a protein is determined by _.

A) hydrogen bonds formed between the components of the peptide linkage
B) pleated sheets
C) the sequence of amino acids
D) a series of helical domains
E) covalent bonds formed between fibroin residues

Question 8

Which of the following are among the major components of prokaryotic ribosomes?

A) 12S rRNA, 5.8S rRNA, and proteins
B) 16S rRNA, 5S rRNA, and 23S rRNA
C) lipids and carbohydrates
D) 18S rRNA, 5.8S rRNA, and proteins
E) 16S rRNA, 5.8S rRNA, and 28S rRNA

Question 9

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

A) valine instead of glutamic acid in the sixth position
B) frameshift substitutions
C) trinucleotide repeats
D) glutamic acid replacing valine in the first position
E) extensive amino acid substitutions

Question 10

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.)

A) 500
B) 3
C) 100
D) 300
E) 1800

Question 11

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?
a() a frameshift mutation in the heterozygous state
b() a deletion of a significant proportion of ribosomal genes (rDNA)

Question 12

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

A) operator proteins
B) repressor proteins
C) hydrophilic proteins
D) structural proteins
E) enzymes

Question 13

The term peptidyl transferase relates to _.

A) elongation factors binding to the large ribosomal subunit
B) base additions during mRNA synthesis
C) discontinuous strand replication
D) peptide bond formation during protein synthesis
E) 5' capping of mRNA

Question 14

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?

Question 15

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

Question 16

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

A) E. coli and yeast
B) E. coli and humans
C) Neurospora and Drosophila
D) Drosophila and humans
E) All of the answers listed are correct.

Question 17

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.

Question 18

What are polyribosomes?

Question 19

A short segment of an mRNA molecule is shown below. The polypeptide it codes for is also shown: 5' -AUGGUGCUGAAG : methionine -valine -leucine -lysine
Assume that a mutation in the DNA occurs so that the fourth base (counting from the 5' end) of the messenger RNA now reads A rather than G. What sequence of amino acids will the mRNA now code for? (You do not need a copy of the genetic code to answer the question.)

A) methionine -methionine -leucine -lysine
B) methionine -lysine -leucine -lysine
C) methionine -valine -leucine -lysine
D) methionine -leucine -leucine -lysine
E) methionine -valine -methionine -lysine

Question 20

The following drawing represents simultaneous transcription and translation in E. coli.
Answer the questions below the drawing. The arrow gives the direction of the RNA polymerase.
a() Is the letter A nearer the 5' or the 3' end of the molecule?
b() Is the letter B nearer the 5' or the 3' end of the molecule?
c() Is the letter C nearer the 5' or the 3' end of the tRNA molecule?
d() What is the "S" value for the large rRNA that is closest to the letter D?
e() Which terminus (N or
C) of the growing polypeptide chain is nearer to the letter E?

Question 21

rDNA is the portion of a genome that is involved in the production of ribosomal RNA.

Question 22

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?

Question 23

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

Question 24

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

Question 25

What is the general ethnic distribution of the sickle -cell gene?

Question 26

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

Question 27

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

Question 28

Given the following table:
where numbers 1 through 4 indicate four supplements that must be added to sustain growth of the organism, determine a possible metabolic pathway that would give the results seen for the four mutant strains, A through D.

Question 29

When a metabolic block occurs in a biochemical pathway, it is common for the amount of the substance immediately prior to that block to increase.

Question 30

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

Question 31

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

Question 32

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?

Question 33

What is the expected proportion of offspring with sickle -cell anemia if both partners are heterozygous for the sickle -cell anemia gene?

Question 34

A procedure that is often used to separate molecules by using their molecular charges is called _.

Question 35

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

Question 36

Prokaryotic and eukaryotic ribosomes are structurally and chemically identical.

Question 37

Assuming that an amino acid sequence is 250 amino acids long, how many different molecules, each with a unique sequence, could be formed?

Question 38

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

Question 39

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

Question 40

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.

Question 41

Sickle -cell anemia is caused by the absence of the alpha chain of hemoglobin.

Question 42

The secondary structure of a protein is dependent on polar interactions among the side chains of the amino acids.

Question 43

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

Question 44

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