Deck 14: Translation and Proteins

Question 1

What is the name of the protein that helps fold other proteins into their final and functional form?

A)ubiquitin
B)flippase
C)proteasomes
D)chaperone
E)collagen

Answer 1

D

Question 2

Which of the following is true regarding the tRNA structure?

A)The nucleotides found in a tRNA molecule can only be adenine,uracil,guanine,and cytosine.
B)The anticodon is found at the 3' end of the tRNA molecule.
C)A tRNA molecule that has an amino acid attached to it is called a charged tRNA.
D)An amino acid binds to the 5' end of the tRNA molecule.
E)The tRNA binds to an mRNA's codon at the variable loop.

Answer 2

C

Question 3

A mutation in EF- Tu would have a DIRECT effect on which part of translation?

A)The next tRNA would not be able to enter the A site of the ribosome.
B)The peptide bond formation would be blocked.
C)The polypeptide would form,but translation termination would be blocked.
D)The small and large subunits would not bind.
E)Translocation would be directly blocked.

Answer 3

A

Question 4

A bacterium's large subunit is 60S and its small subunit is 40S.What is the size of the ribosome containing both subunits?

A)100S
B)120S
C)70S
D)20S
E)80S

Question 5

During initiation in bacterial translation,a particular mutation causes the premature binding of the large ribosome subunit to the small ribosome subunit.Which component of initiation is not working properly?

A)IF3
B)Shine- Dalgarno sequence on the mRNA
C)IF1
D)IF2
E)Ribosome's E site

Question 6

Often point mutations can cause a protein to be made that differs in just one amino acid.Which of the following changes is most likely to cause the greatest change in protein function?

A)a mutation that replaces an asparagine with a glutamine
B)a mutation that replaces a valine with an isoleucine
C)a mutation that replaces a proline with an aspartic acid
D)a mutation that replaces a glutamic acid with an aspartic acid
E)a mutation that replaces a serine with a cysteine

Question 7

The protein shown below provides an example of which level of protein folding?

A)tertiary
B)pentenary
C)quaternary
D)primary
E)secondary

Question 8

The primary structure of a protein is determined by_________ .

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

Question 9

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

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

Question 10

All of the following are examples of posttranslational modifications,EXCEPT_________ .

A)The N- terminal amino acid is often removed or modified.
B)Polypeptide chains can be cleaved to produce a shorter and functional polypeptide.
C)Individual amino acid residues are sometimes modified,such as adding a phosphates,acetyl,or methyl groups can be added.
D)Polypeptides can be degraded and then reassembled to produce entirely different sequenced polypeptides.
E)Prosthetic groups,such as metals or vitamins,can be added.

Question 11

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

Question 12

X- ray crystallography has revealed and confirmed many details about the ribosome.All of the following are such details,EXCEPT_________ .

A)the distance the tRNA must travel between the E,P,and A sites is considered to be relatively short
B)rRNAs are more likely than proteins to be the catalytic molecule of the ribosome
C)the ribosome is a dynamic structure that changes during its different functional states
D)rRNA in the ribosome is in direct contact with the different loops of the tRNA molecule
E)the wobble hypothesis is further supported

Question 13

The term peptidyl transferase relates to_________ .

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

Question 14

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

A)3
B)900
C)1800
D)100
E)300

Question 15

Creutzfeldt- Jakob,Huntington,Alzheimer,and Parkinson disease are all characterized with which part of protein synthesis?

A)initiation
B)N- terminal modification
C)elongation
D)termination
E)protein folding

Question 16

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

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

Question 17

If humans had 25 amino acids instead of 20 amino acids then how many aminoacyl tRNA synthetases would humans have?

A)25
B)3
C)20
D)75
E)4

Question 18

Translation in bacterial and eukaryotic cells has many similarities,but there are also several key differences.Which of the following is one of those differences that is seen in eukaryotes?

A)Eukaryotes use the 5' G- cap and Poly- A- tail on their mRNAs to initiate translation.
B)Eukaryotes only require one release factor that recognizes all three stop codons.
C)Translation and transcription are coupled.
D)Eukartyotic mRNA contains a Shine-Dalgarno sequence that increases the efficiency of translation.
E)Eukaryotic ribosomes are smaller with fewer proteins and RNA molecules.

Question 19

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

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

Question 20

What signals termination of translation in bacteria?

A)a tRNA specific to the stop codon enters the ribosome's A site
B)EF- Tu and EF- G
C)RF1 and RF2
D)the stop amino acid is attached to the growing peptide chain
E)ribozymes

Question 21

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 contain 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 22

Three major types of RNAs are mRNA,rRNA,and tRNA.For each of the conditions below,predict the conseque terms of the population of proteins being synthesized in a particular cell and the effects on individual proteins.
a)An acridine dye-induced mutation adds or deletes single bases in DNA)leads to an mRNA for one protein- producing gene.The condition is heterozygous in the involved cell.
b)A deletion homozygous)that removes approximately half of the rRNA genes.

Question 23

Consider the roles of IF1,IF2,and IF3 during translation.Predict what the effect would be if IF1,IF2,and IF3 were mutated.

Question 24

The accompanying drawing represents simultaneous transcription and translation in E.coli.The direction of the RNA polymerase is given by the arrow.
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 25

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

Question 26

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 27

Provide five reasons why translation is more complex in eukaryotes compared to bacteria.

Question 28

What are polyribosomes and why are they important?

Question 29

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

Question 30

Given the accompanying table:
Supplement 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

Question 31

Sickle- cell anemia is caused by a mutation that changes the second nucleotide of the codon from GAG to GUG.This results in a change of the amino acid from glutamic acid to valine.If the mutation affected the third nucleotide of the codon and changed GAG to GAU then the amino acid would change from a glutamic acid to aspartic acid.Would you predict this change to have the same effect?

Question 32

The problem below relates to the synthesis of several intermediates in the citric acid cycle,which is essential in the production of ATP through aerobic respiration.A set of experimental results relating the growth +)of Neurospora on several media is given in the table.Based on the information provided,present the biochemical pathway for the substances oxaloacetate,fumarate,malate,and succinate,and the locations of the metabolic blocks produced by the various strains.

Question 33

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? Explain.

Question 34

Explain why a eukaryotic mRNA that has begun to be degraded from the 3' end,but still has its complete coding region intact is not efficiently translated.

Question 35

Describe the structure of a tRNA molecule.Your answer should include a list of five important sites on the tRNA and two reasons why tRNA's modified bases are important.

Question 36

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

Question 37

Modular portions of a protein that fold into stable conformations with specific functional capabilities are referred to as_________ .

A)protein domains
B)protein subunits
C)protein quaternary structures
D)protein chaperones
E)protein secondary structures

Question 38

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

Question 39

Sickle- cell anemia is caused when one nucleotide is changed to another nucleotide in the hemoglobin gene.How does this one small change cause the life- threatening disease of sickle- cell anemia?

Question 40

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

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

Question 41

The diseases bovine spongiform encephalopathy and Creutzfeldt-Jakob disease are caused by what kind of protein? How does this protein cause these diseases?

Question 42

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 43

List at least three posttranslational modifications known to occur as a newly synthesized protein matures.

Question 44

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