Final Exam Review Flashcards
What is meant by a membranes transition temperature?
Membrane lipids go from a liquid crystal to a crystalline gel (or vice versa).
How will the transition temperature of a membrane be affected if the amount of unsaturated lipids is increased?
Fluidity will increase and the transition temperature will decrease.
What property of integral membrane proteins allow them to remain embedded in a lipid bilayer?
They have a Transmembrane Domain (TMD) made up of hydrophobic amino acids.
How many ATPs are required to transport 10 K+ ions into the cell?
It takes 1 ATP to import 2 K+, therefore you will need 5 ATPs.
Explain how proton gradients are used in mitochondria in chloroplasts.
Mitochondria: The electrochemical proton gradient across the inner mitochondrial membrane is used to drive ATP synthesis in the critical process of oxidative phosphorylation.
Chloroplasts: The proton gradient functions as an intermediate storage of the harvested light energy and drives ATP synthesis as protons pass across the membrane through the chloroplast ATP synthase.
How can Green Fluorescent Protein (GFP) be used to track the movement of membrane proteins?
If you add GFP to N or C terminus of protein of interest; i.e. make a fusion protein.
What are the major morphological differences between rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER)?
RER has ribosomes on surface, while the SER do not.
What are the major differences in the functions of smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER)?
RER are important for co-translational import, while SER have enzymes which are important for detoxification or storing Ca+.
How are proteins selectively moved from one compartment to another?
Vesicular transport!
A toxin from toadstools called garafraxin, when added to nervse cells, prevents Na+ ion movement from higher to lower concentrations. A possible explanation for this might be:
a) the toxin enters and blocks Na+ channels.
b) garafraxin binds acetylcholine and changes membrane potential.
c) garafraxin antagonizes the ligand that activates Na+ channels.
d) the toxin deactivates the sodium/potassium ATPase pump.
e) both ‘a’ and ‘c’ could be correct.
e) both ‘a’ and ‘c’ could be correct. (add explanation TBD)
Transition of a plasma membrane from a liquid crystal state to a crystalline gel state…?
a) occurs more readily at higher temperatures.
b) requires cholesterol.
c) is aided by phospholipid bilayers embedded with glycoprotein.
d) is favoured when there are more saturated lipids.
e) does not occur in mitochondria inner membranes (IMM)
d) is favoured when there are more saturated lipids. (explanation TBD)
Where in chloroplasts and mitochondria are the highest concentration of protons found?
In the thylakoid lumen and intermembrane space, respectively.
Where is cytochrome c protein normally found?
Cytochrome C is normally found in the mitochondria’s intermembrane space.
What does it mean when cytochrome c is present in the cytoplasm?
When cytochrome c is present, the cell will begin apoptosis.
The N-terminus of an integral membrane protein is in the rough endoplasmic reticulum (RER) lumen. If green fluorescent protein (GFP) is fused to the N-terminus of this protein, which is destined for the plasma membrane, which side of the plasma membrane will glow green?
The extracellular side (explanation TBD)
Where does all protein synthesis initiate?
ribosomes
What are three lines of evidence which support the endosymbiont theory?
Mitochondria and chloroplasts…
1. Have double membranes.
2. Have prokaryotic-type ribosomes.
3. Have their own genomes (circular).
(also, mitochondria inner membrane (IMM) has cardiolipin).
(also, mitochondria & chloroplasts divide by fission, like bacterias).
Which of the following statements regarding the intrinsic pathway of apoptosis are not correct?
a) it can be triggered by hypoxia
b) BAX protein binds to the mitochondria inner membrane.
c) cytochrome c leaks out into the cytosol.
d) executioner caspases are activated
e) nuclear lamins break down.
b) BAX protein binds to the mitochondria inner membrane. (explanation TBD)
Describe the co-translation process for a protein destined for the endoplasmic reticulum (ER) lumen?
Cotranslational translocation occurs when membrane-bound ribosomes insert growing nascent polypeptide chains directly into an ER translocation pore.(explanation tbd)
A mutation in the gene encoding the BiP chaperone protein might:
a) cause the Golgi complex to form incorrectly.
b) produce Transport Vesicles with no ribosomes.
c) cause ER lumen proteins to exit the cytosol.
d) redirect COP II coated vesicles to the ER.
e) result in mis-folded proteins in the ER lumen.
e) result in mis-folded proteins in the ER lumen. (explanation tbd)
What is the initial energy source that drives ATP production via photophosphorylation?
Light!
Which of the following properties represent a difference between prokaryotic and eukaryotic cells?
a) the presence of a membrane-bound nucleus.
b) the presence of membranes consisting of lipid bilayers.
c) the presence of ribosomes to produce proteins.
d) the presence of DNA
e) susceptibility to viruses
a. the presence of a membrane-bound nucleus (explanation tbd)
The synthesis of a plasma membrane receptor protein begins…
a) on free ribosomes in the ER lumen.
b) between the mitochondrial IMM and OMM.
c) on free ribosomes in the cytoplasm.
d) inside the ER translocon.
c) on free ribosomes in the cytoplasm.
COP I and COP II proteins…
a) are synthesized in the ER lumen.
b) direct vesicle traffic in opposite directions .
c) move cargo vesicles from ER to the cis-Golgi Network (CGN).
d) are excreted from the cell.
e) integrate into the Extracellular Matrix (ECM).
b) direct vesicle traffic in opposite directions.
