25 Questions
What is the point of intersection of the straight line with the curve?
The zero time-point
What is the slope of the straight line equivalent to?
V0
Why is the linear part of the curve used to obtain V0?
Because it represents the initial rate of absorption
What is the purpose of drawing a straight line through the linear part of the curve?
To determine V0
What is the relationship between the slope of the straight line and V0?
The slope is equal to V0
What is the standard concentration of substrates and products of a reaction?
1.0 M
Why is it convenient to refer to ΔG under a standard set of conditions?
Because it allows for comparisons between different reactions
What is the primary purpose of defining ΔG under standard conditions?
To compare the thermodynamic properties of different reactions
Under what conditions is ΔG typically defined?
When the substrates and products are at concentrations of 1.0 M
What happens to the equilibrium in the absence of bound substrate?
The equilibrium favors the T-state.
What is the significance of the standard concentration of 1.0 M?
It is a convenient reference point for comparison
What is the effect of substrate binding to every active site in the T-state?
The equilibrium shifts towards the R-state.
What is the relationship between the T-state and the R-state in the absence of bound substrate?
The T-state is favored over the R-state.
What is the role of substrate binding in the shift of the equilibrium?
It shifts the equilibrium towards the R-state.
What is the result of substrate binding to every active site in the T-state?
The equilibrium shifts towards the R-state.
What happens to the velocity of an enzyme-catalyzed reaction at high substrate concentrations?
It becomes independent of [S]
What is the significance of the maximum value of velocity at high substrate concentrations?
The enzyme is fully saturated with substrate
What is the relationship between velocity and substrate concentration at high [S]?
Velocity is independent of [S]
What is the purpose of Fig. 4a in the context of enzyme-catalyzed reactions?
To illustrate the relationship between velocity and [S]
What is the trend of velocity as substrate concentration increases?
It increases rapidly at first and then levels off
What is the main limitation of both models in describing allosteric binding?
They cannot satisfactorily describe the cooperative nature of allosteric binding of substrate to enzymes.
What can be said about the two models in terms of describing the mechanism of action of allosteric enzymes?
They are interchangeable and can be used to describe the mechanism of action of any particular allosteric enzyme.
What is the difference between the two models in describing the cooperative nature of allosteric binding?
Both models have limitations in describing the cooperative nature of allosteric binding.
What is the implication of both models being interchangeable in describing the mechanism of action of allosteric enzymes?
Both models can be used to describe the mechanism of action of any particular allosteric enzyme.
What is the common limitation of both models in describing allosteric enzymes?
They cannot describe the cooperative nature of allosteric binding of substrate to enzymes.
Study Notes
Standard Conditions for ΔG
- ΔG is often referred to under a standard set of conditions, where substrates and products of a reaction are present at concentrations of 1.0 M.
Determining V0
- V0 is obtained by drawing a straight line through the linear part of the curve, starting at the zero time-point.
- The slope of this straight line is equal to V0.
Velocity at High Substrate Concentrations
- At high substrate concentrations, the velocity tends towards a maximum value.
- The rate becomes independent of substrate concentration [S].
Allosteric Binding
- In the absence of bound substrate, the equilibrium favors the T-state.
- As substrate binds to every active site in the T-state, the equilibrium shifts towards the R-state.
Limitations of Models
- Neither model can satisfactorily describe the cooperative nature of allosteric binding of substrate to enzymes.
- Both models can be used interchangeably to properly describe the mechanism of action of any particular allosteric enzyme.
This quiz covers the standard conditions of ΔG, where substrates and products of a reaction are present at concentrations of 1.0 M. Understand the concept and its applications in chemistry.
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