4 Flashcards
- State two laws of Thermodynamics.
1 Energy is neither created or destroyed, but can be transformed from one form to another. The total amount of energy in the universe is constant. #2 When energy is converted from one form to another, the amount of useful energy decreases.
Define energy
The ability to do work
Define Entropy
The loss of complexity or orderliness and useful energy results in an increase in randomness, disorder and less useful energy. Entropy is a measure of this randomness.
Define Kinetic energy
Energy being used to do work. Ex. Light, sound, movement of atoms and molecules, muscle contraction
Define Potential energy
Stored energy availble to do work. Ex. Chemical energy (stored in bonds), concentration gradient.
- Explain endergonic reaction with an example.
Metabolic reactions that require a net input of energy and potential energy is less in reactants than is products. Ex. Co2 and H2o combine to make glucose which has more energy than co2 and h2o. Photosynthesis
- Explain exergonic reaction with examples.
Metabolic reactions that end with a net release of energy and potential energy is more in reactants than in products. Ex. Breakdown of glucose to carbon dioxide and water. Cd and h2o contain less energy than glucose. Cellular respiration.
What are coupled reactions?
Simultaneous reactions in which the exergonic reactions provide the energy that drives the endergonic reaction.
- What is activation energy?
Minimum amount of energy needed to get a reaction started.
- List the factors that contribute to the enzyme substrate specificity?
Complementary shape, charge and hydrophilic/hydrophobic characteristics are responsible for this specificity
What are enzymes?
Biological catalyst - accelerate a chemical reaction without being consumed. Speed biochemichal reactions by lowering activation energy. Most are proteins, some are RNA
- List the factors that have an effect on enzyme activity.
Temperature, Ph, H bonds (hold enzymes in 3d shape)
- Define metabolic pathway
A series of chemical reactions catalyzed by enzymes and are connected by their intermediates
Define Anabolic pathway
The series of chemical reactions that constructs or synthesizes molecules from smaller units, usually requiring input of energy (ATP) in the process.
Define Catabolic pathway
A sequence of degradative chemical reactions that break down complex molecules into smaller units, usually releasing energy in the process
Define Cyclic pathways
A series of chemical reactions in which the final product is used in the first reaction.
- Explain the mechanisms by which enzyme activity is regulated to control the cells metabolism.
Negative feedback: In noncompetetive inhibition, a sustance binds to an allosteric site changing the enzymes shape. A competetive inhibitor blocks the enzymes active sit. Positive feedbck: A product activates the pathway leading to its own production.
- Understand “redox” reactions
Redox reactions link an exergonic process with an endergonic one. An electron donor would undergo an oxidation reaction, losing energy because this is an exergonic reaction. The molecule simultaneously gaining this electron would be reduced in an ender
- What is electron transfer chain?
Groups of proteins embedded in membranes involved in shuttling electrons. Each protein accepts an electron from the molecule before it and passes it to the next releasing energy in each step. Photosynthesis and cellular respiration.
- Define cofactors
Metal ions or small organic molecules (not protein) that are necessary for enzyme function. (vit and min)
Define coenzyme
Organic cofactors. They carry chemical groups/atoms/electrons from reaction to another in metabolic pathways. (NADH, NAD+)
Activation energy
Initial energy required in a reaction for the reactants to become products. Ender and exergonic need activation energy.
Transition state
Activation energy acts on the bonds of the reactants forcing a change. This change brings on the transition state where the bonds on the reactant molecule reach the breaking point and the reaction will run spontaneously to product.
Coupled reactions
Release and store energy in ATP. Potential energy is released when the endmost phosphate group is removed by hydrolysis (exergonic reaction.) Released energy drives an endergonic reaction.
Phosphorylation
Cell uses ATP as energy source by transferring phosphate group. 1. Presence of phosphate may energize target molecule making it more likely to bond with other targets. 2. Change shape of target molecule (muscle contraction).
