Chapter 6 Flashcards
Explain the 1st and 2nd laws of thermodynamics
1st Law: The energy of the universe is constant. Energy can be transferred and transformed, but it cannot be created or destroyed. The first law is also known as the principle of conservation of energy.
2nd Law: Every energy transfer or transformation increases the entropy of the universe.
Explain the usefulness of free energy
It helps in a systems stability and equilibrium. It can help a cell do endergonic reactions.
What is free energy?
The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. The change in free energy of a system (ΔG) is G final state - G initial state. It can be calculated by the equation ΔG = ΔH – TΔS, where ΔH is the change in enthalpy (in biological systems, equivalent to total energy), T is the absolute temperature, and ΔS is the change in entropy.
Distinguish between exergonic and endergonic reactions
Exergonic reaction: A spontaneous chemical reaction, in which there is a net release of free energy. Energy released, spontaneous.
Endergonic reaction: A nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings. Energy required, nonspontaneous.
Describe the function of ATP in the cell
ATP powers cellular work such as chemical work, transport work, and mechanical work.
How does ATP power a cellular process?
By energy coupling (Exergonic reactions such as ATP —> ADP, that have a negative change in free energy that can be used to maintain or increase order in a system by being coupled with reactions that have a positive free energy change.
List the three components of ATP and identify the major class of macromolecules to which it belongs
Sugar Ribose Adenine (nitrogenous base) 3 phosphate groups - Nucleotides. So in simpler terms: ribose, adenine, and phosphate. And belongs to nucleotides.
Describe the energy profile of an enzyme catalyzes reaction. (Include activation energy (EA), free energy change (delta G) and transition state.
Study graph on mind map for this.
Describe the functions of enzymes in biological systems
San enzyme catalyzes a reaction by lowering the activation energy barrier, enabling the reactant molecules to absorbs enough energy to reach the transition state, even at moderate temperature. This eliminates the need to use heat to speed up the reaction because high temperatures can also denature proteins and kill cells.
Explain the relationship between enzyme structure and enzyme specificity.
The specificity of an enzyme is dependent upon the structure of the enzyme.
Example of enzyme catalyzes reaction: Sucrose or hydrogen peroxide
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Why would a reaction not proceed?
There is an inhibitor, low concentration of substrate, or if the enzyme isn’t present at all along with many other things.
Explain the induced fit model of enzyme function and describe the catalytic cycle of an enzyme.
In the induced fit model of enzyme-substrate binding, the shape of the active site of the unbound enzyme is not the exact complement of the shape of the substrate. However, the enzyme does bind to the substrate. After binding of the enzyme to the substrate is initiated, a conformational change in the shape of the active site which results in a new shape of the active site that is complementary to the shape of the substrate.
Also, study mind map for catalytic cycle part of the question.
Explain how enzyme activity can be regulated by or controlled by environmental conditions, cofactors, enzyme inhibitors, and allosteric regulation.
Environmental factors such as temperature and pH levels effect enzyme activity. If the temperature is too cold then not enough collisions (not enough kinetic energy) will occur between the substrate and the enzyme so the reaction it catalyses will be slow. If the temperature is too hot the enzyme will be denatured which means the hydrogen bonds on the active site will break changing the shape of it and no longer allowing substrates to bind. The same with pH levels, it can change the charge of the enzyme which prevents the substrate from binding.
Some enzymes need additional components to show full activity, these are known as cofactors an example of a cofactor is metal ions.
There are two types of enzyme inhibitors one which binds directly to the active site, preventing the substrate from binding and another which binds to another part of the enzyme but still changes its shape not allowing the substrate to bind.
What is an competitive inhibitor?
A substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics.
