6. Metabolism Flashcards
Explain phototrophs vs. chemotrophs
phototroughs:
- obtain energy from the sun
chemotroph:
- obtains energy from chemical compounds
What is catabolism?
Chemical reactions that break down molecules into smaller units:
- produced ATP
Explain autotrophs vs. heterotrophs
autotrophs:
- obtains carbon from non-organic sources (Etc. CO2 -> glucose)
heterotrophs:
- obtains carbon from organic sources
What is anabolism?
Chemical reactions in metabolism that build molecules from smaller units
- Requires energy, usually in the form of ATP
which has more potential energy?
- ionic bonds
- covalent bonds
ionic bonds
but some covalent bonds C-C, C-H (prevalent in organic molecules) are weaker than other ones
Where is the energy in ATP stored?
between the chemical bonds of the three phosphates
What are the laws of thermodynamics?
- Law of conservation: energy is neither created nor destroyed
- Entropy always increases
- (not discussed) The entropy of a closed system of thermodynamic equilibrium approaches a constant as temperature approaches absolute zero
T/F: Heat is released in catabolism and consumed in anabolism
F
Heat is released for both catebolism and anabolism
What is Gibbs free energy
the amount of energy that is available to do work
What is the equation for the total amount of energy?
Total amount of energy = energy available to do work + energy lost to entropy
H = G + TS
T is the absolute temperature in kelvin
S is the energy lost to entropy
What is the equation for Gibbs free energy?
Gibbs = total amount of energy - energy lost to entropy
G = H - TS
T is the absolute temperature in kelvin
S is the energy lost to entropy
In an exergonic reaction what is the sign of G?
exergonic -> spontaneous
G is negative
In an endergonic reaction what is the sign of G?
endergonic -> not spontaneous
G is positive
What type of reaction is the hydrolysis of ATP?
exergonic
H2O -> OH goes to ADP and H goes to P
What is the five-carbon sugar in ATP?
ribose
What do enzymes do in a reaction?
it lowers the height of the activation energy barrier
What is energetic coupling?
when we pair an exergonic reaction and an endogonic reaction
What stage of the reaction is there the most free energy?
The transition state: between reactants and products
what is a substrate?
a reactant in a reaction catalyzed by an enzyme
Name 2 models for substrate and enzyme interaction
substrate fits into the enzyme via..
- lock and key model
- induced fit model (enzyme modes itself to fit the substrate)
What can increase/decrease the activity of an enzyme?
inhibitors and activators
What is negative feedback in a chemical reaction?
When the product of the reaction inhibits the reaction from occurring again
