Chapter 3: Flashcards
(11 cards)
If a protein A has a pI of 4.5, protein B has a pI of 6, and protein C has a pI of 9.5, - at what pH would protein A be obtained through electrophoresis?
a. 2.5
b. 3.5
c. 4.5
d. 5.5
5.5 - Proteins will move in electrophoresis, when the pH of the is greater/smaller than the pI of a protein.
If the pH is lower than pI (acidic), there will be lots of H+ - so the protein/H+ complex will be attracted to the negatively change anode and move toward it. If the pH is greater than the pI (basic), it will be opposite.
We chose 5.5, because we are trying to isolate protein A alone - and now alongside B and C.
When isoelectric point is equal to pH in electrophoresis, what will occur?
The protein will become neutral and stop moving.
What is the function of sodium dodecyl sulfate (SDS) in SDS-PAGE?
a. SDS stabilizes the gel matrix, improving resolution during electrophoresis.
b. SDS solubilizes proteins to give them uniformly negative charges, so separation can be based purely on size.
c. SDS raises the pH of the gel, separating multiunit proteins into individual subunits.
d. SDS solubilizes proteins to give them uniformly positive charges, so separation is based purely on pH.
B - SDS will bind proteins and give them all a negative charge, so that proteins must now be separated by size rather than charge or pH.
Which of the following is not involved in cell migration:
a. Dynein.
b. Flagella.
c. Actin.
d. Centrioles.
d - centrioles.
Define dynein and its function:
A motor protein that is associated with microtubules, that has two head with one always remaining attached. Dynein are involved in the sliding motion of flagella and cilia, as well as vesicle transport in the cell. This will always transport vesicles toward the negative end of the microtubule.
Define kinesin and its function:
A motor protein that is associated with microtubules, that has two head with one always remaining attached. Kinesins are involved in aligning chromosomes during metaphase, and depolymerizing microtubules during anaphase. This will also do vesicle transport, with vesicles always moving toward the positive end of the microtubule.
Define actin and its functions:
Actin is a protein that makes up microfilaments, that serve as the thin filament in the myofibril cross bridge. This is the most abundant protein in eukaryotic cells. Acting has a positive/negative end, allowing motor proteins to move unidirectionally along it.
Define tubulin and its functions:
Tubulin is the protein that makes up microtubules, and is needed to provide structure, chromosome seperation, and intracellular transport using motor protein (kinesin and dynein). Has a positive and negative end to allow motor proteins to move along it.
Which of the following proteins is most likely to be found extracellularly:
a. Tubulin.
b. Myosin.
c. Collagen.
d. Acting
`C - collagen.
Hormones are found in the body in very low concentrations, but tend to have a strong effect. What type of receptors are hormones most likely to act on?
a. Ligand-gated ion channels.
b. Enzyme-linked receptors.
c. G protein coupled receptors.
d. B and C.
e. A, B, and C.
B - Enyzme linked receptors.
C - G protein coupled receptors.
For a ligand in small concetration to cause a larger effect, it must use a second messenger system to create a cascade. Both enzyme-linked receptors and G protein coupled receptors will utilize secondary messengers, while ligand-gated ion channels will not.
