Enzymes & Feedback Inhibition
Speeding up reactions, without being consumed by the reaction.
Ions! (Molecules that are charged, or very polar).
This part of the lipid interacts with water and is hydrophilic.
What is the head?
New phospholipids are synthesized primarily in this organelle's membrane.
What is the smooth ER (endoplasmic reticulum)?
This is the role of the BLM protein.
Unwinds double stranded DNA to repair the DNA.
In feedback inhibition, this molecule regulates the pathway. (The starting substrate, the middle product, or the final product. )
This property of a molecule determines whether it can freely cross the phospholipid bilayer.
What is its polarity/charge? (Also its size)
Name the four parts of a phospholipid.
What are the hydrophillic head, phosphate group, glycerol, and fatty acid tails?
This enzyme helps move newly synthesized lipids between the sides of the bilayer in a random, unspecified way.
What is scramblase?
This protein is responsible for removing phosphate groups.
What is phosphotase?
This binds to the active site of an enzyme, so that it cannot bind to the substrate.
Competitive inhibitor.
Give an example of a molecule that could freely cross a phospholipid bilayer.
These type of fatty acid tails have a double bond, causing a kink in the chain.
What are unsaturated fatty acid tails?
The ER sends new lipids to ____, then the Golgi sends new lipids to the ______.
What are the Golgi and then the plasma membrane?
These molecules regulate the BLM protein.
Post-translational modifications: phosphorylation, ubiquitination, sumoylation
If the final product of a pathway decreases, what would you expect to happen to the inhibition of the pathway.
Inhibition would decrease, allowing the pathway to become more active so more product could be made.
Rank these from most likely to least likely to cross the membrane freely: glucose, Oxygen gas, Na+.
Oxygen gas, glucose, Na+
Name which of the two would have greater fluidity: 15 C with 1 double bond or 17 C with 0 double bonds. Why?
15 C with 1 double bond would be more fluid (because it is shorter with more double bonds/kinks).
This enzyme moves specific phospholipids to the exterior side of the bilayer.
What is floppase?
What is degradation?
1. Orients two molecules together to encourage a reaction between them.
2. Creating partial charges that favor a reaction.
3. Changing orientation of bonds, favoring a reaction.
A student says "Water can cross the phospholipid bilayer very easily because it is a small molecule." Is this true and why?
When temperatures drop, this molecule in animal cell membranes prevent the cell from stiffening up.
In the first step of lipid formation, enzymes always add new lipids to this side of the bilayer.
What is the cytosolic side?
This is the role of both mono ubiquitination and mono sumoylatioin.
Protein regulation (changing functions of proteins).