Chapter 5: Energy and Life Flashcards
1
Q
Energy
A
- The ability to do work
- Kinetic energy: motion
- Potential energy: stored energy
2
Q
Thermodynamics
A
- The study of energy or heat changes
3
Q
Chemical reactions
A
- Making and breaking of chemical bonds
4
Q
1st Law of Thermodynamics
A
- Energy cannot be created or destroyed
- Energy flows in one direction and some of that energy is dissipated as heat
5
Q
2nd Law of Thermodynamics
A
- Entropy: measure of the degree of disorder in a system
6
Q
Substrate (reactants)
A
- Starting molecules of a chemical reaction
7
Q
Products
A
- Molecules at the end of a reaction
8
Q
Endergonic reactions
A
- product contains more energy than reactants
- require input of energy
- not spontaneous
9
Q
Exergonic reactions
A
- produces products that contain less free energy than that produced by original reactants
- release energy
- can be spontaneous
10
Q
Activation energy
A
- initial input of energy needed to start reaction, break bonds
11
Q
Catalysis
A
- lowers the activation energy of a reaction
12
Q
Enzymes
A
- catalysts used by cells to perform particular reactions
- usually proteins but can be nucleic acids
13
Q
Induced fit model
A
- active site + reactant binding site = puzzle piece fit
14
Q
Biochemical pathway
A
- catalyzed reactions occur together in sequence
15
Q
Effect of temperature on enzymes
A
- as temp increases, reaction rate increases
- but, if temp gets too high, enzyme denatures and loses its shape and function
- optimal range for humans is 35-40° C
16
Q
Effect of pH on enzymes
A
- optimal range for humans is 6-8
- except for stomach which is pH 2
17
Q
Allosteric enzymes
A
- cells can control enzymes by altering their shape
- allosteric enzymes are affected by the binding of signal molecules
18
Q
Feedback inhibition
A
- a form of enzyme inhibition where the product of a reaction acts as a repressor
19
Q
Competitive inhibition
A
- binding of inhibitor to active site prevents reaction from occurring
- e.g., Lipitor
20
Q
Noncompetitive inhibition
A
- inhibitor reduces activity of enzymes
- e.g., certain antibiotics
21
Q
ATP
A
- Adenosine triphosphate
1. A sugar
2. An adenine nucleotide
3. A chain of 3 phosphate groups (energy is stored between the phosphate groups, they have same charge and don’t want to be near each other)
22
Q
How is energy released from ATP?
A
- When the endmost phosphate group is broken off an ATP molecule
23
Q
Equation for ATP breakdown
A
ATP –> ADP + Pi + energy
24
Q
Coupled reactions
A
- occur when exergonic reactions are used to pay for the initiation of endergonic reactions
25
Q
Oxidation-reduction reactions
A
- redox reactions
- electrons pass from atoms or molecules to one another
- involve transfer of energy because the electrons retain their potential energy
