AAMC 4 - Bio/Biochem Flashcards
What does cytochrome P450 do?
It oxidizes its substrates.
Cytochrome P450 acts as monooxygenases, where an oxygen atom is inserted into a substrate (the drug of interest), thereby resulting in the oxidation of the substrate.
A defining characteristic of proteins that act as transcription factors (such as STAT5b) is that they:
A. can dimerize.
B. can phosphorylate other proteins.
C. contain a DNA binding domain.
D. are present within the nucleus of the cell.
C. contain a DNA binding domain.
AAMC: The defining characteristic of a transcription factor is that it has a DNA-binding domain that allows it to bind to regulatory nucleic acid sequences in a gene to alter transcription.
Jack Westin: Transcription factors contain a DNA binding domain and through this binding, they can control the rate of transcription of genetic information from DNA.
Where does fatty-acid oxidation (beta-oxidation) occur?
In the mitochondria
What is the rate-limiting enzyme of fatty-acid oxidation?
Carnitine acyltransferase I
Bacteriophages were labeled with radioactive phosphorous (32P) and sulfur (35S). The labeled bacteriophages were then allowed to infect their host cells. At the end of the experiment, the 32P label was found only inside the host cells and the 35S label was found only outside the host cells. This experiment shows that:
A. bacteriophages consist only of DNA and protein.
B. only DNA, not protein, can enter the host cell.
C. only protein, not DNA, can enter the host cell.
D. both DNA and protein can enter the host cell.
B. only DNA, not protein, can enter the host cell.
32P and 35S incorporate into DNA and proteins, respectively. Thus, the results of the experiment indicate that only the bacteriophage DNA enters the cell, not proteins.
A researcher measures the concentration of CO2(aq) in a solution at equilibrium. Which additional quantity must be measured in order to calculate the Henry’s Law constant kH for the gas?
A. Atmospheric pressure
B. Volume of the solvent
C. Partial pressure of the gas
D. Vapor pressure of water
C. Partial pressure of the gas
The Henry’s Law constant kHrelates thesolubility of a gasSto thepressure of that gasPg above the solution and is written as:
S = kH•Pg
Therefore, in addition to the concentration of CO2(aq) in a solution at equilibrium, the partial pressure of the gas Pg must be measured.
Describe Henry’s Law
The Henry’s Law uses the constant kHto relate thesolubility of a gasSto thepressure of that gasPg above the solution and is written as:
S = kH•Pg
What is the relationship between partial pressure of a gas above a solution and solubility of the gas in that solution?
As partial pressure of the gas above solution increases, solubility of the gas in solution increases.
The Henry’s Law uses the constant kHto relate thesolubility of a gasSto thepressure of that gasPg above the solution and is written as:
S = kH•Pg
In what order does aminoacyl-transferase transfer tRNA on a ribosome?
A → P → E
What technique is used to measure transcription levels (mRNA levels)?
RT-PCR
RT-PCR is used to measure transcription/mRNA levels
What technique is used to measure the levels of DNA?
Quantitative PCR
What technique is used to measure translational levels of a protein?
Western Blot
At physiological pH, what is the net charge of the nuclear localization sequence (NDAFEITKRC)?
A. –1
B. 0
C. +1
D. +2
B. 0
At physiological pH, the nuclear localization sequence of MYOD1 (NDAFEITKRC) contains three positively charged amino acids (K, R, and the N-terminal amino acid) and three negatively charged amino acids (D, E, and the C-terminal amino acid). Therefore, the net charge of this sequence at physiological pH is zero.
The nuclear localization sequence of NDAFEITKRC contains how many potential phosphorylation sites?
A. None
B. One
C. Two
D. Three
B. One
There are three amino acids that are phosphorylated in eukaryotes: serine (S), threonine (T), and tyrosine (Y).
The nuclear localization sequence of MYOD1 (NDAFEITKRC) contains one threonine (T) that can potentially be phosphorylated.
Which technique separates proteins independently of their charge?
A. Native PAGE
B. Gel filtration chromatography
C. Ion exchange chromatography
D. Isoelectric focusing
B. Gel filtration chromatography
AAMC: Gel filtration chromatography separates protein only on the basis of their size.
Jack Westin: In gel filtration chromatography, proteins as separated based on size. As the solution travels down the column some smaller particles get stuck in the pores. The larger molecules simply pass by the pores because they are too large to enter the pores.
