Unit 4: Endoplasmic Reticulum, Golgi Complex and Lysosomes - Practice Quiz

1 Which type of vesicle commonly carries proteins and lipids from the ER to the Golgi complex?

2 What is a major function of the endoplasmic reticulum in lipid transport?

3 Which feature distinguishes rough ER from smooth ER?

4 Which type of ER is especially involved in detoxification and lipid synthesis?

5 The endoplasmic reticulum is best described as a:

6 What directs many newly synthesized proteins to the ER?

7 Which particle recognizes an ER signal sequence on a newly forming protein?

8 Proteins entering the ER are commonly synthesized by ribosomes attached to the:

9 What is one important function of molecular chaperones in the ER?

10 Which covalent bond can help stabilize the folded structure of a protein in the ER?

11 What usually happens to a protein that fails to fold correctly in the ER?

12 The Golgi complex is made up mainly of a stack of flattened membrane sacs called:

13 Which Golgi face receives transport vesicles from the ER?

14 Which Golgi face is closest to the plasma membrane and sends materials toward their destinations?

15 Glycosylation is the process of adding which type of molecule to a protein?

16 What is one important result of protein glycosylation in the Golgi?

17 The trans-Golgi network is mainly involved in:

18 Which destination can receive proteins packaged by the Golgi apparatus?

19 Lysosomes contain enzymes that primarily function in:

20 The interior of a lysosome is usually:

21 A newly synthesized secretory protein leaves the rough ER in a transport vesicle. Which coat protein is most directly associated with vesicle formation for transport from the ER to the Golgi?

22 A pancreatic cell produces large amounts of digestive enzymes for secretion. Which ER specialization would be especially abundant in this cell?

23 What would most likely happen if the signal recognition particle could not bind the signal sequence of a nascent secretory protein?

24 A mutation prevents formation of disulfide bonds in a protein that normally functions in the extracellular environment. Which ER process is directly impaired?

25 A transport vesicle carrying a newly synthesized lysosomal enzyme arrives at the Golgi. Which Golgi region should it reach first?

26 A glycoprotein receives carbohydrate modifications as it moves from the cis face toward the trans face of the Golgi. What does this illustrate?

27 A lysosomal hydrolase lacks its normal mannose-6-phosphate tag. Which outcome is most likely?

28 Why can lysosomal enzymes digest cellular materials without normally digesting the cytosol?

29 During autophagy, a damaged mitochondrion is enclosed in a double-membrane autophagosome. What must happen next for its contents to be degraded?

30 A cell treated with a drug that blocks COPII function accumulates newly synthesized secretory proteins in the ER. Which process is directly blocked?

31 A liver cell increases its ability to detoxify lipid-soluble drugs. Which cellular change would most directly support this function?

32 A membrane protein contains a hydrophobic stop-transfer sequence. What is the usual consequence during ER targeting?

33 A misfolded ER protein is repeatedly recognized by chaperones and eventually degraded in the cytosol. Which pathway is involved?

34 If vesicles moving from the trans-Golgi network were prevented from budding, which event would be most directly affected?

35 A Golgi enzyme is experimentally relocated from the medial cisterna to the trans-Golgi network. What is the most likely effect?

36 A membrane protein destined for the plasma membrane is transported from the trans-Golgi network in a secretory vesicle. What is required for delivery to the cell surface?

37 A mutation disrupts the lysosomal proton pump. Which result is most likely?

38 A macrophage engulfs a bacterium into a phagosome. Which event enables enzymatic destruction of the bacterium?

39 A lipid synthesized on the cytosolic leaflet of the ER membrane becomes distributed to both leaflets. Which process best explains this redistribution?

40 A soluble ER resident protein is accidentally transported to the Golgi. Which feature can help retrieve it back to the ER?

41 A secretory protein has an N-terminal signal peptide that is cleaved during translocation. A mutation prevents SRP from binding the signal peptide but does not alter the translocon. What is the most likely immediate consequence?

42 A membrane protein contains an internal hydrophobic signal-anchor sequence whose positively charged residues are more abundant on its N-terminal side. Which topology is most likely produced by the positive-inside rule?

43 A cell expresses a mutant cargo receptor that binds soluble ER proteins but cannot interact with COPII coat components. Which defect is expected?

44 Which alteration would most directly impair anterograde ER-to-Golgi transport while preserving the ability of COPI vesicles to retrieve escaped ER-resident proteins?

45 A steroid-producing cell is experimentally induced to increase synthesis of membrane phospholipids and detoxification enzymes but not secreted proteins. Which structural adaptation is most likely?

46 Why can rough ER and smooth ER be considered functionally continuous despite their different microscopic appearances?

47 A secretory protein repeatedly exposes hydrophobic regions and fails to achieve its native conformation. Which response most directly links this defect to ER quality control?

48 A mutation eliminates the ER retrieval sequence of a soluble chaperone but leaves its folding activity intact. What is the most likely cellular effect?

49 A cell is treated with a drug that blocks formation of disulfide bonds in the ER but does not inhibit peptide-bond synthesis. Which class of protein is most selectively affected?

50 A Golgi-resident enzyme is found predominantly in the cis-Golgi, while another is found predominantly in the trans-Golgi. Which model best explains this distribution?

51 If COPI-dependent retrograde traffic between Golgi cisternae is strongly reduced, which outcome is most likely before widespread organelle disorganization?

52 A glycoprotein reaches the Golgi with a high-mannose N-linked oligosaccharide. Which processing sequence is most plausible?

53 A lysosomal hydrolase is synthesized normally but lacks mannose-6-phosphate on its N-linked oligosaccharides. Which defect is most likely?

54 A mutation removes a luminal cysteine from a Golgi glycosyltransferase but leaves its catalytic residues intact. Why could glycosylation still be defective?

55 A soluble lysosomal enzyme binds its sorting receptor in the trans-Golgi network. What event normally promotes release of the enzyme from the receptor after delivery?

56 A membrane protein destined for the plasma membrane contains a cytosolic sorting motif that recruits clathrin adaptors at the trans-Golgi network. What is the most likely consequence of mutating this motif?

57 A lysosomal membrane protein is synthesized with a cytosolic tail that contains a tyrosine-based sorting signal. What is the primary significance of this signal?

58 A mutation reduces activity of the lysosomal V-type proton ATPase but does not alter lysosomal membrane permeability. Which change is expected first?

59 During macroautophagy, inhibition of lysosomal fusion with autophagosomes would most directly cause which phenotype?

60 A macrophage internalizes bacteria into phagosomes, but a defect prevents phagosome–lysosome fusion. Which result is most likely?