Where a protein goes
1.[2p] Put these compartments in the order Palade's radioactive leucine passed through them.
Put these compartments in the order Palade's radioactive leucine passed through them.
Zymogen granules
Golgi
Rough endoplasmic reticulum
Condensing vacuoles
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a, b, c, d
2.[3p] Translating a secretory protein's mRNA without membranes gave a product slightly longer than the mature protein. What did that show?
Translating a secretory protein's mRNA without membranes gave a product slightly longer than the mature protein. What did that show?
The answer is: There is an extra amino-terminal sequence that is removed during transport into the endoplasmic reticulum
The answer is: There is an extra amino-terminal sequence that is removed during transport into the endoplasmic reticulum
The answer is: There is an extra amino-terminal sequence that is removed during transport into the endoplasmic reticulum
3.[2p] Adding microsomal membranes after translation is complete allows the protein to enter them just as well as adding them beforehand.
Adding microsomal membranes after translation is complete allows the protein to enter them just as well as adding them beforehand.
The answer is: False
4.[3p] Match each targeting signal to its destination.
Match each targeting signal to its destination.
A short run of basic residues, not cleaved
A positively charged amphipathic helix, cleaved on arrival
Serine, lysine and leucine at the far end
A hydrophobic sequence at the amino end, clipped off
No signal at all
the secretory pathway
the mitochondrial matrix
the cytosol
the nucleus
a peroxisome
Show the answer
A short run of basic residues, not cleaved: the nucleus A positively charged amphipathic helix, cleaved on arrival: the mitochondrial matrix Serine, lysine and leucine at the far end: a peroxisome A hydrophobic sequence at the amino end, clipped off: the secretory pathway No signal at all: the cytosol
5.[3p] Why is Anfinsen's conclusion, that sequence determines structure, incomplete as a description of folding in a cell?
Why is Anfinsen's conclusion, that sequence determines structure, incomplete as a description of folding in a cell?
The answer is: Folding cannot be an exhaustive search, and at 200 g per litre a partly folded chain is likely to aggregate before it finishes
The answer is: Folding cannot be an exhaustive search, and at 200 g per litre a partly folded chain is likely to aggregate before it finishes
The answer is: Folding cannot be an exhaustive search, and at 200 g per litre a partly folded chain is likely to aggregate before it finishes
6.[3p] What is the commonest cystic fibrosis mutation actually doing?
What is the commonest cystic fibrosis mutation actually doing?
The answer is: Producing a channel that would largely work, but which fails quality control and is destroyed before reaching the surface
The answer is: Producing a channel that would largely work, but which fails quality control and is destroyed before reaching the surface
The answer is: Producing a channel that would largely work, but which fails quality control and is destroyed before reaching the surface
7.[3p] Which observations support the endosymbiotic origin of mitochondria?
Which observations support the endosymbiotic origin of mitochondria?
Select all that apply
8.[2p] How many proteins does the human mitochondrial genome encode?
How many proteins does the human mitochondrial genome encode?
9.[3p] Why does chloramphenicol, an inhibitor of bacterial ribosomes, suppress human bone marrow?
Why does chloramphenicol, an inhibitor of bacterial ribosomes, suppress human bone marrow?
The answer is: Mitochondrial ribosomes are bacterial in type, so respiratory subunits made inside mitochondria are lost, and marrow is among the most demanding tissues
The answer is: Mitochondrial ribosomes are bacterial in type, so respiratory subunits made inside mitochondria are lost, and marrow is among the most demanding tissues
The answer is: Mitochondrial ribosomes are bacterial in type, so respiratory subunits made inside mitochondria are lost, and marrow is among the most demanding tissues