Question 1

Characteristics of the mammalian translocon include all EXCEPT:

Accepted Answer

A)  sec61 complex at the core. 
B)  transmembrane protein-conducting channel. 
C)  BiP carries out ATP-dependent protein folding. 
D)  composed of a single transmembrane spanning (TMS) protein. 
E)  all are true. 
A)  sec61 complex at the core. 
B)  transmembrane protein-conducting channel. 
C)  BiP carries out ATP-dependent protein folding. 
D)  composed of a single transmembrane spanning (TMS) protein. 
E)  all are true. D

Question 2

Nascent (newly formed) proteins are often assisted in folding and ____ by a family of helper proteins known as ____.

Accepted Answer

A)  unfolding; molecular principals 
B)  refolding; molecular principals 
C)  refolding; molecular chaperones 
D)  unfolding; molecular chaperones 
E)  unfolding; amyloids 
A)  unfolding; molecular principals 
B)  refolding; molecular principals 
C)  refolding; molecular chaperones 
D)  unfolding; molecular chaperones 
E)  unfolding; amyloids C

Question 3

The information for folding each protein into its unique three-dimensional architecture resides within its ____.

Accepted Answer

A)  primary structure 
B)  amino acid content 
C)  content of hydrophobic amino acids 
D)  content of basic amino acids 
E)  none are true 
A)  primary structure 
B)  amino acid content 
C)  content of hydrophobic amino acids 
D)  content of basic amino acids 
E)  none are true A

Question 4

Eukaryotic secretory proteins are synthesized and translocated via the endoplasmic reticulum. Order the following sequence of events for this process.
A.signal sequence removeD.
B.glycosylation in the ER lumen.
C.signal sequence synthesis on ribosomes.
D.SRP binds signal sequence and subsequently binds SRP-receptor.
E.ribosome dissociates.

Accepted Answer

A)  A, C, E, B, D 
B)  C, D, A, B, E 
C)  C, A, D, B, E 
D)  A, C, B, D, E 
E)  C, B, D, E, A 
A)  A, C, E, B, D 
B)  C, D, A, B, E 
C)  C, A, D, B, E 
D)  A, C, B, D, E 
E)  C, B, D, E, A

Question 5

Discuss the structure of the chaperonin GroES-GroEL complex found in E. coli.​

Accepted Answer

​In the GroES-GroEL complex, GroEL is a

Question 6

The appropriate sequence for ubiquitination of proteins to be degraded is:
A.multiple ubiquitinations may occur on a protein substrate,
B.ubiquitin-protein ligase (E3) transfers ubiquitin to free amino groups on the protein,
C.E3 selects a protein for degradation by the nature of the N-terminal amino acid,
D.ubiquitin-carrier protein (E2) picks up ubiquitin,
E.ubiquitin-activating enzyme (E1) attaches via ATP-dependent formation of thioester bond to C-termini of ubiquitin,

Accepted Answer

A)  A, C, B, D, E 
B)  E, D, A, B, C 
C)  D, E, C, A, B 
D)  C, E, D, B, A 
E)  E, D, C, B, A 
A)  A, C, B, D, E 
B)  E, D, A, B, C 
C)  D, E, C, A, B 
D)  C, E, D, B, A 
E)  E, D, C, B, A

Question 7

In the proteosomes, the 19S cap acts as a ____ complex for the recognition and selection of ____ proteins for ____ by the 20S proteosomes core.

Accepted Answer

A)  hydrolysis; unfolded; disposal 
B)  regulatory; unfolded; disposal 
C)  hydrolysis; ubiquitinylated; degradation 
D)  regulatory; ubiquitinylated; degradation 
E)  all are true 
A)  hydrolysis; unfolded; disposal 
B)  regulatory; unfolded; disposal 
C)  hydrolysis; ubiquitinylated; degradation 
D)  regulatory; ubiquitinylated; degradation 
E)  all are true

Question 8

The ribosome and the ____ form a common conduit for transfer of the nascent protein through the ____ membrane.

Accepted Answer

A)  translocon; endoplasmic reticulum 
B)  signal sequence; plasma 
C)  EF-G; endoplasmic reticulum 
D)  chaperonin; plasma 
E)  all are true 
A)  translocon; endoplasmic reticulum 
B)  signal sequence; plasma 
C)  EF-G; endoplasmic reticulum 
D)  chaperonin; plasma 
E)  all are true

Question 9

All are correct statements regarding the protein degradation process involving ubiquitin EXCEPT:

Accepted Answer

A)  The modified protein is degraded by an ATP-dependent protease complex. 
B)  The ubiquitin binding to the protein to be degraded leads to a novel branched protein. 
C)  The ubiquitin is covalently attached to a cysteine residue in the protein to be degraded. 
D)  Three additional proteins (E1, E2, and E3) are involved in the ligation of ubiquitin to the protein. 
E)  Ubiquitin is a highly conserved protein. 
A)  The modified protein is degraded by an ATP-dependent protease complex. 
B)  The ubiquitin binding to the protein to be degraded leads to a novel branched protein. 
C)  The ubiquitin is covalently attached to a cysteine residue in the protein to be degraded. 
D)  Three additional proteins (E1, E2, and E3) are involved in the ligation of ubiquitin to the protein. 
E)  Ubiquitin is a highly conserved protein.

Question 10

The primary function of Met-aminopeptidase is to:

Accepted Answer

A)  cleave large inactive pro-proteins. 
B)  remove leader peptides after translocation. 
C)  transfer a Met to the C-terminal end for translocation. 
D)  remove invariable Met and introduce N-terminal diversity. 
E)  all are true. 
A)  cleave large inactive pro-proteins. 
B)  remove leader peptides after translocation. 
C)  transfer a Met to the C-terminal end for translocation. 
D)  remove invariable Met and introduce N-terminal diversity. 
E)  all are true.

Question 11

In E. coli, ____ bound to large ribosomal subunits facilitates transfer to ____ to bind ____ residues, thus avoiding non-productive folding.

Accepted Answer

A)  chaperonin; trigger factor; H-binding 
B)  trigger factor; DnaK; hydrophobic 
C)  DnaK; Hsp70; ionic 
D)  Hsp70; chaperonin; hydrophilic 
E)  all are true 
A)  chaperonin; trigger factor; H-binding 
B)  trigger factor; DnaK; hydrophobic 
C)  DnaK; Hsp70; ionic 
D)  Hsp70; chaperonin; hydrophilic 
E)  all are true

Question 12

Which of the following is responsible for Alzheimer's disease?

Accepted Answer

A)  polyglutamine aggregates 
B)  neurofibrillary tangles of polymeric microtubule-binding protein tau 
C)  extracellular deposits of amyloid-β and intracellular neurofibrillary tangles of microtubule-binding protein tau 
D)  mutation in the huntingtin gene 
E)  none of the above 
A)  polyglutamine aggregates 
B)  neurofibrillary tangles of polymeric microtubule-binding protein tau 
C)  extracellular deposits of amyloid-β and intracellular neurofibrillary tangles of microtubule-binding protein tau 
D)  mutation in the huntingtin gene 
E)  none of the above

Question 13

In a protein targeted for destruction, ubiquitin is most commonly attached to a _____ residue, forming a/an ______ bond between ubiquitin and the targeted protein.

Accepted Answer

A)  Ser; ester 
B)  Lys; amide 
C)  α-amine group of the N-terminal amino acid if the particular residue is Arg, Lys, His, Phe, Tyr, Trp, Leu, Asn, Gln, Asp or Glu; amide 
D)  Glu; acid anhydride 
E)  Cys; thioester 
A)  Ser; ester 
B)  Lys; amide 
C)  α-amine group of the N-terminal amino acid if the particular residue is Arg, Lys, His, Phe, Tyr, Trp, Leu, Asn, Gln, Asp or Glu; amide 
D)  Glu; acid anhydride 
E)  Cys; thioester

Question 14

Proteolytic cleavage has been shown to be involved in all of the following processes EXCEPT:

Accepted Answer

A)  inactivation of regulatory enzymes. 
B)  elimination of the N-terminal Met residue. 
C)  activation of zymogens. 
D)  elimination of signal sequences after the protein has reached its proper location. 
E)  digestion of dietary proteins. 
A)  inactivation of regulatory enzymes. 
B)  elimination of the N-terminal Met residue. 
C)  activation of zymogens. 
D)  elimination of signal sequences after the protein has reached its proper location. 
E)  digestion of dietary proteins.

Question 15

Which of the following proteins would be commonly ubiquitinated and thus degraded by the proteasome?

Accepted Answer

A)  proteins with Met as the N-terminal amino acid 
B)  proteins with short sequences rich in Pro, Glu, Ser and Thr 
C)  proteins with short sequences rich in Trp, Thr, and Phe 
D)  proteins having a C-terminal Cys for the formation of a thioester bond with ubiquitin 
E)  none of the above 
A)  proteins with Met as the N-terminal amino acid 
B)  proteins with short sequences rich in Pro, Glu, Ser and Thr 
C)  proteins with short sequences rich in Trp, Thr, and Phe 
D)  proteins having a C-terminal Cys for the formation of a thioester bond with ubiquitin 
E)  none of the above

Question 16

Discuss the functions of HtrA proteases.​

Accepted Answer

HtrA proteases are a class of proteins i

Question 17

Discuss the significance of proteolytic cleavage in post-translational processing.​

Accepted Answer

​First, proteolytic cleavage introduces

Question 18

Explain how the amino acids at the amino terminus determine the susceptibility of proteins to degradation through the ubiquitin pathway.​

Accepted Answer

The E3 subunit of the ubiquitin pathway

Question 19

​Explain how mitochondrial preproteins are imported into the mitochondria.

Accepted Answer

Once synthesized, mitochondrial preprote

Question 20

What does Hsp (as in Hsp60) stand for?

Accepted Answer

A)  helical stabilizing protein 
B)  hydrophobic sequestering protein 
C)  heat shock protein 
D)  high-histidine subunit protein 
E)  none of the above 
A)  helical stabilizing protein 
B)  hydrophobic sequestering protein 
C)  heat shock protein 
D)  high-histidine subunit protein 
E)  none of the above

Exam 31: Completing the Protein Life Cycle: Folding, Processing, and Degradation

Characteristics of the mammalian translocon include all EXCEPT:

Nascent (newly formed) proteins are often assisted in folding and ____ by a family of helper proteins known as ____.

The information for folding each protein into its unique three-dimensional architecture resides within its ____.

Discuss the structure of the chaperonin GroES-GroEL complex found in E. coli.​

In the proteosomes, the 19S cap acts as a ____ complex for the recognition and selection of ____ proteins for ____ by the 20S proteosomes core.

The ribosome and the ____ form a common conduit for transfer of the nascent protein through the ____ membrane.

All are correct statements regarding the protein degradation process involving ubiquitin EXCEPT:

The primary function of Met-aminopeptidase is to:

In E. coli, ____ bound to large ribosomal subunits facilitates transfer to ____ to bind ____ residues, thus avoiding non-productive folding.

Which of the following is responsible for Alzheimer's disease?

In a protein targeted for destruction, ubiquitin is most commonly attached to a _____ residue, forming a/an ______ bond between ubiquitin and the targeted protein.

Proteolytic cleavage has been shown to be involved in all of the following processes EXCEPT:

Which of the following proteins would be commonly ubiquitinated and thus degraded by the proteasome?

Discuss the functions of HtrA proteases.​

Discuss the significance of proteolytic cleavage in post-translational processing.​

Explain how the amino acids at the amino terminus determine the susceptibility of proteins to degradation through the ubiquitin pathway.​

​Explain how mitochondrial preproteins are imported into the mitochondria.

What does Hsp (as in Hsp60) stand for?

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, Tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Enzymeskinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Nitrogen Acquisition and Amino Acid Metabolism

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

The Reception and Transmission of Extracellular Information

Filters

Nascent (newly formed) proteins are often assisted in folding and by a family of helper proteins known as .

Discuss the structure of the chaperonin GroES-GroEL complex found in E. coli.

In the proteosomes, the 19S cap acts as a complex for the recognition and selection of proteins for by the 20S proteosomes core.

The ribosome and the form a common conduit for transfer of the nascent protein through the membrane.

In E. coli, bound to large ribosomal subunits facilitates transfer to to bind residues, thus avoiding non-productive folding.

In a protein targeted for destruction, ubiquitin is most commonly attached to a _ residue, forming a/an __ bond between ubiquitin and the targeted protein.

Discuss the functions of HtrA proteases.

Discuss the significance of proteolytic cleavage in post-translational processing.

Explain how the amino acids at the amino terminus determine the susceptibility of proteins to degradation through the ubiquitin pathway.

Explain how mitochondrial preproteins are imported into the mitochondria.