ENDOMEMBRANES EXAM QUESTIONS WITH CORRECT
ANSWERS 100% VERIFIED
What are the three major subdivisions of the Endomembrane system? - Correct Answers -Secretory pathway -Lysosomal pathway -Endocytic pathway How do proteins travel through the endomembrane system? - Correct Answers -Proteins only enter through the start of each pathway, (never from the middle) and never leave pathway until they have reached their destination What are 3 types of protein that enter the endomembrane system upon translation? - Correct Answers 1. Proteins destined for secretion
- Plasma membrane proteins
- Proteins that are destined to be endomembrane resident proteins
What type of proteins does the rough endoplasmic reticulum synthesize? - Correct Answers Proteins destined for secretion, lysosomes, or membranes True or false: the cytosolic surface of the ER have ribosomes - Correct Answers True: these ribosomes are responsible for synthesizing proteins for import into the ER What does the smooth endoplasmic reticulum synthesize? - Correct Answers Lipids and steroids Where do newly synthesized proteins exit the ER? - Correct Answers The transitional ER (where two types of ER meet) How do proteins stay in the ER? - Correct Answers Proteins that stay in the ER have a ER retention signal (KDEL or HDEL sequence based on amino acids) at carboxyl ends -Even if they get out of the ER into the cis cisternae of the Golgi their ER targeting signal gets them sorted into vesicles and brings them back into the ER What is retrograde movement? - Correct Answers Backward movement (from trans to cis) of vesicles 1 / 2
What is the unfolded protein response? - Correct Answers Production of chaperone proteins and the expansion of the ER to promote proper folding and processing triggered by misfolded proteins in the ER lumen What proteins are part of membranes? - Correct Answers Proteins inserted into membranes (only partially translocated) are destined for the ER, membranes of another organelle, or the plasma membrane These proteins stay within the membrane once they are inserted into the ER membrane What proteins are not part of membranes? - Correct Answers Proteins that are soluble and completely translocated into membrane Destined for secretion or transfer to lysosomes Never part of membrane Where does translation of proteins occur? - Correct Answers On free ribosomes Which ribosomes becomes attached to the ER? - Correct Answers The ribosomes that produce proteins for export What are some properties of proteins that signal ER entry? - Correct Answers -8+ hydrophobic amino acid residues -helps maintain that portion of the polypeptide within the ER and involved in translocation What is the fate of abnormally folded proteins? - Correct Answers May be retained by chaperone molecules so they can be refolded or sent to the proteasome for degradation What is required for proteins to cross membranes? - Correct Answers (1) Membrane must contain a specialized protein channel that recognizes and transports particular proteins across membranes and (2) proteins must contain a specific signal sequence that interacts with a receptor protein part of the transport channel How are cells targeted to a specific location? - Correct Answers (1) each protein contains information in amino acid sequences that serve as an address (2) There is a specific protein receptor that corresponds to each type of targeting signal
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