General Chemistry Flashcards
Under what conditions do experimenters generate a Michaelis-Menten plot?
- Constant enzyme concentration
- Increasing substrate concentration
Plot reaction velocity v. substrate concentration
What is indicated by a small Km v a large Km
Small - high binding affinity
Large - low binding affinity
What is catalytic efficiency and what does it predict?
The efficiency of an enzyme in converting substrate –> product
Recall that kcat describes speed of an individual enzyme (higher speed, better efficiency - want this to be large)
Recall that Km describes the affinity of the enzyme for the substrate (lower Km, better efficiency)
Catalytic efficiency = kcat/ Km
What is the difference in how vmax and Km are depicted on a Lineweaver-Burk plot
Seen as the reciprocal
What happens to Vmax and Km in each of the types of inhibition?
Competitive Same Increases Active
Uncompetitive Decreases Decreases Allosteric
Mixed Decreases Increases or decreases Allosteric
Noncompetitive Decreases Same Allosteric
Why does Vmax remain the same and Km increase in competitive inhibition?
Inhibitor binds to the enzyme’s active site – prevents the substrate from binding – effect of inhibitor can be decreased by increasing the concentration of substrate – same Vmax can be reached but binding affinity decreases (Km increases because more substrate is required to reach the same effect)
Where does the inhibitor bind in uncompetitive inhibition and what is the effect of adding more substrate?
Selectively binds to the ES complex – adding more substrate doesn’t help achieve Vmax therefore Vmax decreases (cannot get the same effect) – Km also decreases (as inhibitors bind ES complex, there is less uninhibited complex – Le Chatlier’s Principle – need to replenish the lost ES complex)
What must occur in order for a zymogen to become a functional enzyme??
Must be cleaved e.g trypsinogen –> trypsin
What is the most common form of feedback regulation??
Negative feedback – enzyme’s product or a product further down the pathway inhibits the enzyme, decreasing flux through the pathway
Describe the concept of cooperativity using hemoglobin
Hemoglobin contains four identical subunits that bind one oxygen molecule each – once one subunit binds oxygen the next subunit is much more likely to also bind another oxygen subunit
Can be described by Hill coefficient
<1 Negative cooperativity – binding of substrate to the first subunit makes the binding of substrate to the second subunit less likely
> 1 Positive cooperativity – binding of substrate to the first subunit makes the binding of substrate to the second subunit more likely
=1 No effect
What determines the element that a specific atom is?
The number of protons – its atomic number
Why do the repelling positive charges of the nucleus not rip it apart?
Because of the strong nuclear force – attractive nuclear force that holds protons and neutrons together
What is the difference between diamagnetic and paramagnetic atoms
Diamagnetic – all paired electrons – do not interact strongly with magnets
Paramagnetic – unpaired electrons – strongly affected by nearby magnetic fields – do not possess a permanent magnetic charge
Describe the periodic trends of
Electronegativity
Ionization energy
Electron affinity
Zeff
Increases upward and across the periodic table
Increases upward and across the periodic table (second ionization energy is significantly higher)
Increases upward and across the periodic table
Zeff – increases across a row
what does a
