Chem/Phys (AAMC 2) Flashcards
Proteasomes
a protein complex in cells containing proteases; it breaks down proteins that have been tagged by ubiquitin.
Proteasomes are protein complexes which degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Enzymes that help such reactions are called proteases.
lysosomes
One of the key organelles involved in digestion and waste removal is the lysosome. Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria. Lysosomes are like the stomach of the cell
found in animal cells, are the cell’s “garbage disposal.” The digestive processes take place in these, and enzymes within them aid in the breakdown of proteins, polysaccharides, lipids, nucleic acids, and worn-out organelles.
apoptosis
Apoptosis is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, chromosomal DNA fragmentation, and global mRNA decay.
covalent attachement
includes chemical reactions such as amine, aldehyde, and thiol coupling reactions.
Energy of Photon
E=hf
E= hc/λ,
h= planack’s constant= 6.62 × 10 −34 J ∙ s
λ=wavelength
c= speed of light=3 × 10 8 m/s.
The concentration of enzyme for each experiment was 5.0 μM. What is kcat for the reaction at pH 4.5 with NO chloride added when Compound 3 is the substrate?
A.2.5 × 10–2 s–1
B.1.3 × 102 s–1
C.5.3 × 103 s–1
D.7.0 × 105 s–1
The fact that the rate of product formation did not vary over time for the first 5 minutes implies that the enzyme was saturated with substrate. Under these conditions, kcat = Vmax/[E] = (125 nM/s)/5.0 μM = 2.5 × 10–2 s–1
Absorption of ultraviolet light by organic molecules always results in what process?
A.Bond breaking
B.Excitation of bound electrons
C.Vibration of atoms in polar bonds
D.Ejection of bound electrons
B.Excitation of bound electrons
The half-life of a radioactive material is:
the time it takes for half of all the radioactive nuclei to decay into their daughter nuclei.
Peptide Bond
A peptide bond is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 of one alpha-amino acid and N2 of another, along a peptide or protein chain
A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). This is a dehydration synthesis reaction (also known as a condensation reaction), and usually occurs between amino acids.
Based on the relative energy of the absorbed electromagnetic radiation, which absorber, a peptide bond or an aromatic side chain, exhibits an electronic excited state that is closer in energy to the ground state?
A.An aromatic side chain; the absorbed photon energy is higher.
B.An aromatic side chain; the absorbed photon energy is lower.
C.A peptide bond; the absorbed photon energy is higher.
D.A peptide bond; the absorbed photon energy is lower.
B.An aromatic side chain; the absorbed photon energy is lower.
B because aromatic side chains absorb in the near UV region of the electromagnetic spectrum, which has longer wavelengths, and hence lower energy, than peptide bonds. Because the energy of the photon matches the energy gap between the ground and the excited state, this implies that the aromatic side chain has more closely spaced energy levels.
Kinase
a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the substrate gains a phosphate group and the high-energy ATP molecule donates a phosphate group.
phosphoryl transfer from kinases comes from the___ phosphate of ATP.
γ‐phosphate of ATP
all kinases require an Mg2+‐nucleotide complex as one substrate. Protein kinases catalyse the transfer of the γ‐phosphoryl group of ATP (see also : Adenosine Triphosphate) to the hydroxyl group of a serine, threonine or tyrosine side‐chain, or to the nitrogen atom of a histidine, of a protein substrate.
A patient puts on a mask with lateral openings and inhales oxygen from a tank as shown.
What phenomenon causes static air to be drawn into the mask when oxygen flows?
A.Doppler effect
B.Venturi effect
C.Diffusion
D.Dispersion
B.Venturi effect
he answer to this question is B because oxygen pressure is the sum of the oxygen static pressure P and the oxygen flow pressure ρv2/2. In the area of the mask openings, Pair = P + ρv2/2, thus Pair > P. Air enters the mask because the static pressure of the air is larger than the static pressure of the oxygen in flow. This is the Venturi effect, and the mask is called the Venturi mask.
What causes duplex DNA with a certain (A + T):(G + C) ratio to melt at a higher temperature than comparable length duplex DNA with a greater (A + T):(G + C) ratio?
A.Stronger van der Waals forces of pyrimidines
B.Stronger van der Waals forces of purines
C.Increased π- stacking strength
D.Reduced electrostatic repulsion of phosphates
C.Increased π- stacking strength
The answer to this question is C. G–C base pairs form stronger π-stacking interactions than A–T base pairs, thereby creating the most thermal stability. This disparity has often been used to explain the increased melting temperature of DNA rich in GC content.
What are the structural features possessed by storage lipids?
A.Two fatty acids ester-linked to a single glycerol plus a charged head group
B.Three fatty acids ester-linked to a single glycerol
C.Two fatty acids ester-linked to a single sphingosine plus a charged head group
D.Three fatty acids ester-linked to a single sphingosine
B.Three fatty acids ester-linked to a single glycerol
The answer to this question is B because triacylglycerols are neutral storage lipids. They consist of three fatty acids ester-linked to a single glycerol.
