MCB 150 exam 3 mastering biology answers – Flashcards
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Which of the following classes of lipids is synthesized in the Golgi apparatus?
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**Glycolipids
Phospholipids
Cholesterol
Ceramide
Triglycerides
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The cis-Golgi:
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a. prevents the retrograde transfer of proteins from the Golgi to the RER.
b. is the cellular location where stop transfer sequences are attached to transmembrane proteins.
c. is the portion of the Golgi apparatus from which fully modified proteins are directed to their final destinations.
d. is physically continuous with the trans-Golgi.
**e. is the portion of the Golgi apparatus closest to the RER and nucleus.
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Which one of the following cellular processes is most likely to happen in the Golgi?
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Translation on membrane bound ribosomes
Synthesis of membrane phospholipids
**Synthesis of sphingomyelin
Synthesis of ceramide
N-linked glycosylation
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You are working late in lab and discover that the labels you put on a TEM of a Golgi apparatus have rubbed off. How can you determine which face of the Golgi is the cis face?
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a. The cisternae farthest from the RER is the cis face.
b. The cis face of the Golgi is always fused with the RER.
c. The cis face of the Golgi is always fused with the nucleus.
d. There is always an ERGIC closest to the cis face.
**e. Vesicles leaving the ER are typically smaller than vesicles leaving the Golgi, so the side of the Golgi receiving small vesicles is the cis face.
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A mannose-6-phosphate group is a chemical signal which directs a protein displaying it to which one of the following locations?
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A lysosome
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Which of the following statements about the Golgi is/are correct? Choose all that apply.
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Answers:
a. The majority of metabolism of Golgi in plants is due to cell wall polysaccharide biosynthesis.
b. Vesicles can move from one layer of the Golgi stack to another by budding and fusion.
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Which of the following statements about secreted proteins is/are correct? Choose all that apply.
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answers:
a. Secreted proteins are synthesized on membrane-bound ribosomes, not free cytosolic ribosomes.
b. Secreted proteins that are constitutively expressed are exported as they are prepared, as opposed to being released as a response to a signal.
c. Secreted proteins are likely to have received N-linked glycosylation in the rough ER.
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Which of the following statements about lipid processing is/are correct? Choose all that apply.
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answers:
a. Sphingomyelin is a phospholipid made in the Golgi.
b. Glycolipids are sugar molecule(s) attached to a membrane lipid.
c. Ceramide can be made into either sphingomyelin or a glycolipid depending on what enzyme encounters ceramide first.
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Which of the following statements about lysosomes is incorrect?
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a. The hydrolysis of ATP to ADP helps maintain the pH of the lysosome by means of proton transfer.
b. If a lysosome encounters a molecule that it cannot digest, it is possible that it may fill with that material and rupture.
c. They can degrade macromolecules such as proteins, carbohydrates, and lipids.
d. Lysosomes function in phagocytosis and autophagy.
**e. They must maintain a pH of 7 in order to function properly.
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In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?
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on the inside surface of the vesicle
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In which one of the following compartments will mannose-6-phosphate receptors most likely be found?
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A late endosome
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Which one of the following statements about lysosomes is correct?
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a. The function of most lysosomal enzymes can be lost without observable medical consequences.
** b. Lysosomes can be used to degrade intracellular material as well as material taken into the cell from the extracellular environment.
c. There is a lower concentration of protons in a lysosome than in the matrix of a mitochondrion.
d. The pH in a lysosome is altered by pumping protons across the lysosomal membrane using an electron transport chain.
e. Only proteins, nucleic acids, and polysaccharides are degraded in a lysosome.
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How is a cell protected from degradation by acid hydrolases? Choose all that apply.
a. Each cell contains only one lysosome, which limits potential damage from acid hydrolases.
b. Acid hydrolases are optimally active at a pH lower than what is found in the cytoplasm.
c. Acid hydrolases only degrade foreign proteins and DNA.
d. Acid hydrolases are sequestered away from the cytoplasm by a lipid bilayer membrane.
e. Acid hydrolases only degrade molecules containing a mannose-6-phosphate, which allows them to break down only what is targeted for degradation.
answer
1. Acid hydrolases are optimally active at a pH lower than what is found in the cytoplasm.
2. Acid hydrolases are sequestered away from the cytoplasm by a lipid bilayer membrane.
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Approximately how many types of lysosomal storage disorders are there?
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Approximately the same as the number of acid hydrolases
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Which of the following characteristics distinguishe(s) a lysosome from a late endosome? Choose all that apply.
a. Lysosomes do not contain acid hydrolases, while late endosomes do.
b. Lysosomes has proton pumps in its membrane, while late endosomes do not.
c. Fewer (if any) mannose-6-phosphate receptors will be found in a lysosome compared to a late endosome.
d. A lysosome has a lower pH than a late endosome.
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1. Fewer (if any) mannose-6-phosphate receptors will be found in a lysosome compared to a late endosome.
2. A lysosome has a lower pH than a late endosome.
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Which of the following statements about lysosomes is/are correct? Choose all that apply.
a. Autophagosomes form in the cytosol around old or broken down organelles; later, the autophagosome fuses with a lysosome.
b. All eukaryotes have lysosomes to carry out the recycling needs of a cell.
c. Lysosomes release the monomeric building blocks (like amino acids and nucleotides) into the cell.
d. Resident lysosomal proteins display a mannose-6-phosphate group during their production which targets them to a late endosome.
e. Lysosomes are acidic because of the effect of the hydrolases on the organellar pH.
f. If one of the many types of acid hydrolases found in the lysosome is nonfunctional, a lysosomal storage disease can develop.
answer
1. Autophagosomes form in the cytosol around old or broken down organelles; later, the autophagosome fuses with a lysosome.
2.Lysosomes release the monomeric building blocks (like amino acids and nucleotides) into the cell.
3. Resident lysosomal proteins display a mannose-6-phosphate group during their production which targets them to a late endosome.
4. If one of the many types of acid hydrolases found in the lysosome is nonfunctional, a lysosomal storage disease can develop.
