Chapter 8 Flashcards
Metabolism
All the chemical reactions in an organism
Catabolic pathways
-breakdown of molecules into smaller compounds.
-release the energy stored in complex molecules
Anabolic pathways
-Building smaller molecules into larger
- Require/absorb energy
Energy
capacity to cause change
Kinetic energy
the energy of motion
Thermal energy
Heat - the kinetic energy of randomly moving atoms or molecules.
Potential energy
Stored energy due to arrangement and placement. Ex: a ball at the top of a hill has high potential energy. Because of its position at the top of the hill, the ball can be push and will roll down.
Chemical energy
energy stored within bonds, which can be released to do work. Ex: The body breaks apart glucose, the energy released from breaking the bond is used by the body as energy.
First law of thermodynamics
Energy cannot be created or destroyed. It can be transformed.
Second law of thermodynamics
every energy transformation increases the entropy of the universe
Entropy
measure of disorder
Free energy
system’s energy available to perform work
Exergonic reactions
Energy is released
Endergonic Reaction
Energy is absorbed
ΔG
Free energy change
ΔH
change in Enthalpy
ΔS
Change in Entropy
Enzymes
Biological catalysts. They speed up metabolic reaction by lowering the activation energy (energy needed to start reaction)
Spontaneous
a reaction that occurs without an input of energy. Exergonic reactions are spontaneous
energy coupling
the use of exergonic processes to drive endergonic ones
Substrates
The substrate binds to the active site of the enzyme
Active site
a “pocket” found on the surface of the enzyme. Every active site has a specific substrate that can fit in it.
Induced fit
SIMPLY EXPLAINED: the active site “hugs” the substrate. The “hug” puts them closer together, making the enzyme work better.
Actual explanation: Interactions between substrates and active sites causes the enzyme to slightly change shape. This enhances the ability of the enzyme to catalyze the chemical reaction
Catalysis in the Enzyme’s Active Site
Some of the surrounding amino acids in the active site have side chains (R chains) that help turn the substrate into the product.
denaturing of enzymes
Each enzyme has certain environments that it works best in. Change in pH and temperature can denature the enzyme, meaning it changes its shape, decreasing its function.
MAIN FACTORS
-Temperature
-pH
-Chemicals
Cofactors
SIMPLE DEFINITION: Cofactors are helper molecules or ions that enzymes need to work properly
Actual definition: Cofactors are non-protein molecules or ions that assist enzymes in performing their catalytic functions
Coenzymes
organic cofactors ex. vitamins
Competitive inhibitors
Binds to the active site of an enzyme. Competes with substrate. Increasing the amount of substrate may overcome this type of inhibition.
Noncompetitive inhibitors
binds to another part of an enzyme, causing the enzyme to change shape, and the active site stops working.
Allosteric Regulation
Some enzymes have a site called the allosteric site. This is NOT the active site, it is an ADDITIONAL site on the enzyme.
An activator binds to the allosteric site to increase the enzyme’s activity, while an inhibitor binds to decrease or block the enzyme’s activity.
Why is allosteric regulation important?
Allosteric regulation turns the enzyme “on” and “off”. This regulates metabolic reactions, preventing too much or too little products from being produced.
cooperativity
SIMPLER DEFINTION: the binding of one molecules “unlocks” the other active sites on the molecule, increasing enzyme activity
ACTUAL DEFINITION: when one molecule binding to an enzyme makes it easier (or harder) for more molecules to bind, affecting how active the enzyme is.
Feedback inhibition
SIMPLE DEFINTION: product binds to enzyme, changing its shape, preventing the enzyme from creating more products. The prevents too many products being made.
ACTUAL DEFINITION: The end product acts as an allosteric inhibitor of an enzyme early in the metabolic pathway. This prevents overproduction.
ATP to ADP
In ATP, a phosphate breaks away, and ATP is now ADP. This releases 7.3 k/cal of energy to be used by the body to do work.
