Chapter 6,7 Enzymes And Metabolism Flashcards
(28 cards)
Metabolism
Sum total of all chemical reactions that occur within a living organism
Chemical reaction
Process in which one or more substance are changed to other substances
Reaction is reservable
ATP can drive a reaction in a desired direction
Catalysts can be used to speed up the rate of reaction
Energy
The ability to promote change
Kinetic energy
Associated with movement
Potential energy
Energy that a substance possesses because of its structure or location
Glucose - it can potentially be oxidized to CO2 and water
Thermodynamics
Study of energy interconversions
First Law of thermodynamics
Energy cannot be created or destroyed
Second law of thermodynamics
Transfers of energy, or transformation of energy, increases the entropy of a system
Gibbs free energy
H = G+ TS
Spontaneous Reactions
Occurs with out an additional input of energy
The change in free energy (G) that occurs as a result of a chemical reaction can be used to determine if a reaction is spontaneous
Evaluating free energy change
G < 0 negative free energy
G > 0 positive free energy
Exergonic
Releases free energy spontaneous
Endergonic
Requires addition of free energy from the environment
Does not proceed spontaneously
Cellular respiration
Glycolysis
Involves the breakdown of glucose
Can occur in the presence of oxygen equals aerobic, or in the absence of oxygen equals an anaerobic
10 steps can be grouped into three phases
Energy investment, cleavage, energy liberation
Yields 2 NADH and 4 ATP , 2 Pyruvate
Happens in cytosol
Phases of glycolysis
1. Energy investment
2 ATP hydrolyzed
Phosphates from these ATP are used to convert the glucose to fructose - 1,6 bisphosphate over three sequential reactions
Phases of glycolysis
2. Cleavage
Fructose 1,6 bisphosphate (6C) is cleaved into two molecules of glyceraldehyde -3- phosphate (3 carbon each)
Three phases of glycolysis
3. Energy liberation
Two glyceraldehyde -3-phosphate molecules are broken down into two Pyruvate molecules
Produces 2 NADH and 4ATP
Breakdown of Pyruvate
In eukaryotes, Pyruvate is transported to the mitochondria matrix
Broken down by the enzyme complex called pyruvate dehydrogenase
For each Pyruvate
One molecule of CO2 is removed
Remaining Acetyl group is attached to coenzyme to create acetyl CoA
NADH is made
Citric Acid Cycle
Metabolic cycle
Particular molecules enter the cycle while others leave
Citric acid cycle
Acetyl group is removed from Acetyl CoA and attached to oxaloacetate (4C) to form citrate (6C)
Series of 8 steps produces 2 CO2, 3NADH, 1FADH2, 1 GTP (used to make 1 ATP)
Oxaloacetate is regenerated and starts the cycle again of Acetyl CoA is available
Oxidative Phosphorylation
6 CO2, 4ATP, 10 NADH AND 2FADH2
Turn oxidative phosphorylation, high energy electrons are removed from NADH and FADH2 to make more ATP by phosphorylation of ADP
Typically requires oxygen
Electron Transport Chain
A group of protein complexes and small organic molecules embedded in the inner mitochondrial membrane
Accept and release electrons
Transfers are redox reactions
Oxygen
The electron transport chain is also called the respiratory chain
Oxygen that we breathe is used in the process as the final electron acceptor
In the last step, electrons are transferred from cytochrome oxidase to molecular oxygen