Bio/Biochem Flashcards
What is a clathrin?
Clathrin is a protein that plays a major role in the formation of coated vesicles.
Coat-proteins, like clathrin, are used to build small vesicles in order to transport molecules within cells.
Creates a lattice.
What is nuclear localization signal or sequence (NLS)?
A nuclear localization signal or sequence (NLS) is an amino acid sequence that ‘tags’ a protein for import into the cell nucleus by nuclear transport. Typically, this signal consists of one or more short sequences of positively charged lysines or arginines exposed on the protein surface.
Epilepsy in motor seisures bc of massive synchronous firing. The excitation spreads from small focus are to a larger area of the cortex. A drug to work against epilepsy would be effective if it did?
A. increase the neuron firing threshold
B. increase extracellular sodium concenentration
C. shorten depol stage
D. decreases axon permiability to negative ions
A. increase neuron firitn threshold
This would reduce the firing in the beginning in the epileptic focus. When you increase the threshold required, you decrease the chance of individual neurons firing thus lowering the chance for overfiring.
When concentrated urine is produced, what part of the kidney will the glomerula filatrate have the highest concentration?
in the medullary portion of the collecting duct bc it is the last part as it exits the kidney, which comes after the cortical portion.
Which approach does NOT measure Na+K+ATPase activity?
A. measuring the rate of ATP hydrolysis
B. measureing the change in ion concentration within liposome
C. measuring free energy of the ion transport
D. measuring the rate of ADP production
C. measuring free energy of the ion transport
When measuring activity, you only look at kinetics NOT thermodynamics. Since free energy is a therm quantity, it cannot measure kinetics.
Voltage gated vs. ion gated channels
Ca2+ channel is an ion chanel
voltage gated channels open and close based on changes on the memrane potential
Neurotrasmitter attaches to ligand gated channel on the post synaptic neuron.
How does a transcription factor work?
It binds to the DNA and recruits RNA polymerase to transcribe the DNA sequesnce of interest.
Why isnt orienthine found in proteins even though it is an AA?
There is no codon for it in the genetic code. It can still form peptide bonds but there is no code for it.
- What happens after 2-3 hours of starvation?
- What happens after 10 hours?
- stored glycogen in liver breaks down to glucose
- Adrenal gland produces glucocorticoids once stored glycogen reserves are low. Glucocorticoids will break muscle protein from skeletal muscle to increase serum glucose levels.
Where does post-translational modification, in which a translated polypeptide cleaved to a mature protein, happen ?
In the endomembrane system, which includes golgi, endoplasmic reticulum and lysosomes.
What are the differing characteristics of a fast and slow twich muscle fiber?
slow:
- red fibers (red due to oxygenated blood cells)
- high amounts of mitochondria due to ability to recycle O2
- can maintain long periods of excerice
Fast:
- white (due to high amount of Ca+ sarcoplasmic reticulum)
- low levels of mit
- good for sprints, explosive power and use of ATP at highest lever
What cause Ca2+ to reenter the sarcoplasmic reticulum after muscle contraction?`
Active transport driven by ATP hydrolysis. (against its concentration gradient)
What is the composition of E coli membrane?
75% protien and 25% phospholipid
What is ΔG= -RTln(Keq) when Keq= 1
ΔG=0 bc ln (1)=0
the reaction is thermoneutral thus the reaction does not require/produce ATP to proceed
What makes a sphingolipide?
The virus mentioned is HIV
What is the dependent and independent variable in the following experiment
Dependent: what you measure = Retinol fleuresence
Independent Variable: what you change/ condition = STRA 6and LRAT condition
Below question
Uncompetitive inhibitor alters both Km and Vmax with the same ratio, thus no change in slope
