Exam 2 Flashcards
Metabolism
Sum of all chemical reactions in an organism.
Thermodynamics (first two laws)
- Energy can’t be created or destroyed. - It is transferred between forms.
- Energy transfer always increases entropy - Never perfect transfer of energy.
Spontaneous reactions release _____ energy.
Free.
Free energy - The energy of a system that can be used to do work.
Nonspontaneous vs spontaneous reactions
Reactions that do not release free energy. - nonspontaneous
A spontaneous process occurs without the need for a continual input of energy from some external source, while a nonspontaneous process requires such.
Endergonic - nonspontaneous
Exergonic - spontaneous
Endergonic Reactions
Require an input of free energy. Nonspontaneous. Creates more products than reactants. Ex: photosynthesis. (positive change of Gibbs free energy).
If a reaction is endergonic, ATP can be used by an enzyme to power the reaction.
Exergonic Reactions (provide example as well)
Release free energy. Spontaneous. More reactants than products. Ex: ATP hydrolysis. (negative change of Gibbs free energy)
ATP/ADP
ATP is the most commonly used cellular “energy molecule”. ATP has much more free energy than ADP and P. ATP can be hydrolyzed. ADP and P can undergo dehydration synthesis to make more ATP.
What does ATP do?
ATP powers reactions in a cell that increase order and/or are endergonic (non-spontaneous).
ATP phosphorylates transport proteins.
ATP binds noncovalently to motor proteins and then is hydrolyzed.
ATP hydrolysis.
ATP hydrolysis is a chemical reaction that breaks a phosphate bond on ATP, a molecule that stores and supplies energy in cells.
What makes an enzyme function different than other enzymes?
Their shape and molecular properties.
Enzymes hold onto substrates using weak forces. The interaction can change the shape of the enzyme.
Ways that stabilize the transition state of enzymes:
Bending the substrate(s)
“Micro conditions” of a reaction
Aligning two substrates next to each other in the correct orientation.
Activation Energy
All reactions require some energy to go.
Enzymes reduce the activation energy of a reaction by bending substrates, positioning them next to each other.
Denaturation
Enzymes are held together by weak bonds that can be broken easily by heat or other changes to the environment. Temperature, PH, osmolality, and other conditions can denature enzymes.
How is aerobic respiration powered?
Eating and breathing.
Oxygen is a reactant in breaking down food, CO2 is a waste product and is exhaled.
Is food being broken down exergonic or endergonic?
Is energy to convert adp and p to atp exergonic or endergonic?
exergonic
endergonic
Photosynthesis vs cellular respiration
opposite chemical reactions that transform energy from one form to the other
Photosynthesis
Uses H2O and CO2 with light energy to build glucose.
6CO2 becomes reduced and 6H2O becomes oxidized.
Fixes carbon which can be used to build organic molecules.
Plants, protists (algae), bacteria.
Cellular Respiration
Cellular respiration uses O2 and glucose to generate ATP and leaves CO2 and H2O.
Oxidizes glucose and reduces oxygen
Oxidizing Reactions
Reactions that remove hydrogen (and electrons)
Reducing Reactions
Reactions that add hydrogen (and electrons)
Redox Reactions
reducing/oxidizing reactions. These reactions are complementary, one gets reduced the other gets oxidized.
NAD+
Glucose becomes oxidized while NAD+ becomes reduced in several steps of cellular respiration.
What is cellular respiration?
A metabolic process that builds ATP from ADP and P.
Cellular Respiration breakdown into 3 stages
Glycolysis
Citric acid cycle
Oxidative phosphorylation
Glycolysis
Splits glucose into pyruvate and generates a small amount of ATP.
Splits sugar into 2 pyruvate molecules and generates 2 ATP and 2 NADH.
Citric Acid Cycle
Completes the breakdown of glucose and generates a small amount of ATP (and a lot of NADH).
Oxidative Phosphorylation
Uses NADH and O2 to phosphorylate ADP into ATP.
Phosphorylate - Introduce a phosphate group into a molecule or compound.
Glycolysis Steps
1.) Uses 2 ATP to phosphorylate glucose.
2.) The double phosphorylated 6 carbon intermediate is split
3.) Oxidizes the phosphorylated 3 carbon molecule to produce NADH
4.) Generates 4 ATP molecules.
Pyruvate Oxidation
Moves pyruvate into the mitochondria and converts it into acetyl CoA.
Citric Acid Cycle Steps
1.) Acetyl is added to Oxaloacetate making a 6 carbon sugar.
2.) Two carbons are released as CO2, and 2 NADH are produced. (Carbon is released, NADH is produced)
3.) Redox reactions regenerate oxaloacetate.
Where is most of the ATP made during cellular respiration generated?
Oxidative phosphorylation