Question 1

Which of the following processes has proteolytic cleavage been shown to be involved with?

Accepted Answer

A) inactivation of regulatory enzymes 
B) elimination of disulfide bridges 
C) activation of zymogens 
D) elimination of large protein sequences after the protein has reached its proper location 
A) inactivation of regulatory enzymes 
B) elimination of disulfide bridges 
C) activation of zymogens 
D) elimination of large protein sequences after the protein has reached its proper location C

Question 2

Which of the following receives partially folded protein intermediates during chaperone-dependent folding?

Accepted Answer

A) chaperonin 
B) Hsp40 
C) Hsp60 
D) Hsp70 
A) chaperonin 
B) Hsp40 
C) Hsp60 
D) Hsp70 A

Question 3

Which of the following,together with signal recognition particles,deliver the nascent protein chain to specific membrane complexes that mediate integration into and across the membrane?

Accepted Answer

A) signal receptors 
B) translocons 
C) Golgi 
D) ribosomes 
A) signal receptors 
B) translocons 
C) Golgi 
D) ribosomes A

Question 4

Which of the following types of sequences is required for proteins to remain embedded in the ER membrane with their C-termini on the cytosolic face of the ER?

Accepted Answer

A) translocator 
B) leader 
C) translocational 
D) stop-transfer 
A) translocator 
B) leader 
C) translocational 
D) stop-transfer

Question 5

Which of the following does NOT occur during ubiquitination degradation of proteins?

Accepted Answer

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 C-terminal amino acid. 
D) Ubiquitin-carrier protein (E2)picks up ubiquitin. 
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 C-terminal amino acid. 
D) Ubiquitin-carrier protein (E2)picks up ubiquitin.

Question 6

Eukaryotic secretory proteins are synthesized and translocated via the endoplasmic reticulum.Which of the following steps is part of this process?

Accepted Answer

A) signal sequence phosphorylation 
B) glycosylation in the ER lumen 
C) signal sequence addition 
D) ribosome assembly 
A) signal sequence phosphorylation 
B) glycosylation in the ER lumen 
C) signal sequence addition 
D) ribosome assembly

Question 7

Mitochondrial pre-sequences are positively charged amphipathic sequences retained in the unfolded stage.With which of the following molecular chaperones do they associate?

Accepted Answer

A) Hsp40 
B) Hsp70 
C) chaperonin 
D) Hsp90 
A) Hsp40 
B) Hsp70 
C) chaperonin 
D) Hsp90

Question 8

Which of the following is a highly conserved protein that is involved in protein degradation?

Accepted Answer

A) Met-aminopeptidase 
B) ubiquitin 
C) degradase 
D) peptidyl transferase 
A) Met-aminopeptidase 
B) ubiquitin 
C) degradase 
D) peptidyl transferase

Question 9

Which of the following ribosomal bound molecule helps avoid non-productive protein folding during transfer to DnaK?

Accepted Answer

A) chaperonin 
B) trigger factor 
C) Hsp40 
D) Hsp70 
A) chaperonin 
B) trigger factor 
C) Hsp40 
D) Hsp70

Question 10

Which of the following is a characteristic of Hsp90 chaperones?

Accepted Answer

A) They comprise more than 20% of total cytosolic proteins in eukaryotes. 
B) Their action depends on cyclic binding and hydrolysis of GTP. 
C) They direct proteins toward degradation pathways. 
D) Their major purpose is conformational regulation of signal transduction molecules. 
A) They comprise more than 20% of total cytosolic proteins in eukaryotes. 
B) Their action depends on cyclic binding and hydrolysis of GTP. 
C) They direct proteins toward degradation pathways. 
D) Their major purpose is conformational regulation of signal transduction molecules.

Question 11

Which of the following contains the information required for proper protein folding?

Accepted Answer

A) the primary structure 
B) the amino acid content 
C) the content of hydrophobic amino acids 
D) the content of basic amino acids 
A) the primary structure 
B) the amino acid content 
C) the content of hydrophobic amino acids 
D) the content of basic amino acids

Question 12

Which of the following is a characteristic of chaperonin?

Accepted Answer

A) formed of 3 stacked rings of subunits 
B) allows folding to proceed in a unprotected environment 
C) small,cylindrical protein complexes 
D) sequesters partially folded proteins 
A) formed of 3 stacked rings of subunits 
B) allows folding to proceed in a unprotected environment 
C) small,cylindrical protein complexes 
D) sequesters partially folded proteins

Question 13

Which of the following is the primary function of Met-aminopeptidase?

Accepted Answer

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

Question 14

Which of the following is the proper sequence for transport of inner mitochondrial membrane proteins?

Accepted Answer

A) TOM;TIM23 
B) SAM;TOM;TIM22 
C) TOM;TIM22 
D) SAM;TOM;TIM23 
A) TOM;TIM23 
B) SAM;TOM;TIM22 
C) TOM;TIM22 
D) SAM;TOM;TIM23

Question 15

Which of the following amino acids in a protein targeted for destruction is most commonly the receptor for ubiquitin?

Accepted Answer

A) Ser 
B) Lys 
C) Asn 
D) Tyr 
A) Ser 
B) Lys 
C) Asn 
D) Tyr

Question 16

Which of the following is a characteristic of protein translocation systems?

Accepted Answer

A) Translocons passively move proteins across the membrane. 
B) Proteins to be translocated are made as preproteins containing distal blocks of amino acid sequences that act as sorting signals. 
C) Membranes involved in translocation have specific protein receptors exposed on their cytosolic faces. 
D) Pre-proteins are maintained in a tightly folded,translocation-competent conformation through interaction with molecular chaperones. 
A) Translocons passively move proteins across the membrane. 
B) Proteins to be translocated are made as preproteins containing distal blocks of amino acid sequences that act as sorting signals. 
C) Membranes involved in translocation have specific protein receptors exposed on their cytosolic faces. 
D) Pre-proteins are maintained in a tightly folded,translocation-competent conformation through interaction with molecular chaperones.

Question 17

Which of the following pairs forms a common conduit for transfer of the nascent protein through the endoplasmic reticulum membrane?

Accepted Answer

A) ribosome and translocon 
B) signal sequence and plasma membrane 
C) EF-G and endoplasmic reticulum 
D) chaperonin and plasma membrane 
A) ribosome and translocon 
B) signal sequence and plasma membrane 
C) EF-G and endoplasmic reticulum 
D) chaperonin and plasma membrane

Question 18

Which of the following statements concerning protein folding is correct?

Accepted Answer

A) The GroES protein serves as the cap for GroEL. 
B) The Hsp70 proteins bind to hydrophilic regions of the protein,thus preventing aggregation. 
C) The Hsp60 proteins are rarely known as chaperonins. 
D) The GroEL protein provides an environment that leads to possible aggregation. 
A) The GroES protein serves as the cap for GroEL. 
B) The Hsp70 proteins bind to hydrophilic regions of the protein,thus preventing aggregation. 
C) The Hsp60 proteins are rarely known as chaperonins. 
D) The GroEL protein provides an environment that leads to possible aggregation.

Question 19

Which of the following helper proteins assist nascent (newly formed)proteins to fold?

Accepted Answer

A) molecular chaperones 
B) transcription factors 
C) molecular principals 
D) amyloids 
A) molecular chaperones 
B) transcription factors 
C) molecular principals 
D) amyloids

Question 20

Which of the following is a characteristic of HtrA proteases?

Accepted Answer

A) chaperones at low temperatures 
B) ATP-dependent 
C) proteases at low temperatures 
D) bind folded proteins 
A) chaperones at low temperatures 
B) ATP-dependent 
C) proteases at low temperatures 
D) bind folded proteins

Exam 32: Completing the Protein Life Cycle: Folding, processing, and Degradation

Which of the following processes has proteolytic cleavage been shown to be involved with?

Which of the following receives partially folded protein intermediates during chaperone-dependent folding?

Which of the following,together with signal recognition particles,deliver the nascent protein chain to specific membrane complexes that mediate integration into and across the membrane?

Which of the following types of sequences is required for proteins to remain embedded in the ER membrane with their C-termini on the cytosolic face of the ER?

Which of the following does NOT occur during ubiquitination degradation of proteins?

Eukaryotic secretory proteins are synthesized and translocated via the endoplasmic reticulum.Which of the following steps is part of this process?

Mitochondrial pre-sequences are positively charged amphipathic sequences retained in the unfolded stage.With which of the following molecular chaperones do they associate?

Which of the following is a highly conserved protein that is involved in protein degradation?

Which of the following ribosomal bound molecule helps avoid non-productive protein folding during transfer to DnaK?

Which of the following is a characteristic of Hsp90 chaperones?

Which of the following contains the information required for proper protein folding?

Which of the following is a characteristic of chaperonin?

Which of the following is the primary function of Met-aminopeptidase?

Which of the following is the proper sequence for transport of inner mitochondrial membrane proteins?

Which of the following amino acids in a protein targeted for destruction is most commonly the receptor for ubiquitin?

Which of the following is a characteristic of protein translocation systems?

Which of the following pairs forms a common conduit for transfer of the nascent protein through the endoplasmic reticulum membrane?

Which of the following statements concerning protein folding is correct?

Which of the following helper proteins assist nascent (newly formed)proteins to fold?

Which of the following is a characteristic of HtrA proteases?

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

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Lipid Biosynthesis

Membranes and Membrane Transport

The Reception and Transmission of Extracellular Information

Enzymes Kinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Nutrition and the Organization of Metabolism

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Nitrogen Acquisition and Amino Acid Metabolism

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Synthesis and Degradation of Nucleotides

Recombinant Dna: Cloning and Creation of Chimeric Genes

DNA Metabolism: Replication, recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Post-Transcriptional Regulation of Gene Expression

Metabolic Integration and Organ Specialization

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