Protein Structure
Name the four components attached to an alpha carbon in an amino acid.
What are the amino group, carboxy group, hydrogen, and side chain (R group)?
Name the two types of inhibitors to enzymes.
What are competetive and noncompetitive inhibitors?
This property of a molecule determines whether it can freely cross the phospholipid bilayer.
What is its polarity/charge? (Also its size)
Which side of the Golgi faces the ER? What is the other side called?
What is the cis Golgi? What is the trans Golgi?
What three types of interactions help proteins fold?
elecrtostatic attractions, van der Waals attraction, hydrogen bonds
A cell has plenty of the final product in a metabolic pathway. Why would you want to inhibit an enzyme near the beginning of the pathway?
It will prevent the cell from unnecessarily making more of a product it already has enough of.
Rank these from most likely to least likely to cross the membrane freely: glucose, oxygen gas, Na+.
oxygen gas, glucose, Na+
What are the three enzymes involved in the building of the lipid bilayer in the endoplasmic reticulum?
What are scramblase, flippase, and floppase?
A vesicle is traveling from the ER towards the Golgi. Which coat protein complex helps form this vesicle?
What is COPII?
True or False: The geometry of an alpha helix allows it to be a channel.
FALSE! Alpha helix are wrapped too tightly and do not act as a channel.
An inhibitor binds to an enzyme, causing it to change shape. What kind of inhibitor is this? Where does it bind?
What is a noncompetitive inhibitor? Somewhere other than the active site.
What are two ways that you can increase fluidity in phospholipid membranes?
What are adding more unsaturated fatty acid tails (double bonds) and shortening length?
To remain floating in the ER lumen, what kind of transfer sequence is needed?
What is an N-terminal start sequence and no stop sequences?
Which proteins assist the vesicle in fusing with the target membrane? Where are these proteins located?
What are v-snares and t-snares? V-snares are located on the vesicle and t-snares are located on the target membrane.
A protein is exposed to conditions that will disrupt hydrogen bonds but don't break covalent bonds. Which levels of protein structure will be disrupted?
A protein is inactive until a phosphate group is added to it. What type of enzyme would be responsible for activating it?
What is a kinase?
Cholesterol stiffens the membrane, and if the temperature is cold it'll prevent the membrane from stiffening up.
Name the two types of modifications that can occur to proteins in the ER?
What are forms disulfide covalent bonds and glycosylation?
Does the coating come off during vesciular transport? If so, when?
Yes the coating comes off after the vesicle pinches off from the membrane and before the vesicle docks and fuses with its target membrane.
Name an amino acid sequence that would form a beta barrel.
NP-P-NP-C-NP-P (alternating hydrophobic and hydrophillic amino acids)
This is what happens when only one ubiquitin is added to a protein.
What is protein regulation? (Change in protein function)
Why do phospholipids form a spontaneous bilayer in water, but cholesterol and SDS don't?
Because of their GEOMETRY! Phospholipids have two tails and have a cylinder-like shape, while SDS has only one tail and a cone shape.
This is a soluble ER-resident protein and forms disulfide covalent bonds.
What is protein disulfide isomerase (PDI)?
A vesicle is leaving the Golgi and heading to an early endosome. Name all of the proteins involved in the vesicle budding off of the membrane.
Adaptin, clathrin, and dynamin.