BSCI170: Metabolism and Enzymes

notes from 10/20 + 10/22

What is metabolism, and what are it’s functions?

total chemical reactions of an organism

• Maintains stability of the cell

• Provides building blocks for the synthesis of new cellular materials

• Highly organized and controlled

What are nutrients, and give some examples

supply of monomers needed for cell growth

• Examples of nutrients: CHNOPS

What are metabolic pathways, and what are their characteristics?

Metabolic pathways: series of interconnected reactions that convert a starting substrate into a product

• Can be linear or cyclic

What is anabolism, and give an example

Anabolism: biosynthesis; uses energy to build molecules

• Dehydration synthesis is anabolic

• energy is consumed

What is catabolism, and give an example

Catabolism: digestive; releases energy to break down molecules

• Hydrolysis is catabolic

• energy is released

ATP hydrolysis turns ATP into…

ATP → ADP + p_i 

• Catabolic

• You make energy by breaking ATP bc there is a lot of potential energy stored in the bonds

Why is ATP so important?

phosphate groups are very electronegative. As you add more phosphate groups, the bonds become increasingly unstable. Adding the third phosphate group allows it to break off easily, thus releasing energy

Naming of Phosphate groups in ATP

Alpha: phosphate group closest to the adenosine

Beta: 2nd closest

Gamma: 3rd closest

What is kinetic energy

energy of movement

potential energy

stored energy of objects

chemical energy

potential energy stored within chemical bonds

Gibbs Free Energy equation

ΔG = ΔH - TΔS

What is thermodynamics

study of energy and energy transfer involving physical matter

1st law of thermodynamics

energy of the universe is constant (energy can transferred and transformed but it cannot be created or destroyed)

2nd law of thermodynamics

 the state of entropy of the entire universe, as an isolated system, will always increase over time (in energy transfer, some amount of energy is lost as heat)

High entropy equals…

high disorder = low energy

Low entropy equals…

low disorder = high energy

Gibbs free energy equation: ΔH

total energy in the system (enthalpy)

Gibbs Free energy Equation: ΔG

ΔG = change in free energy

Gibbs Free Energy Equation: ΔS

ΔS = amount of energy lost to entropy from the system’s total energy change

Gibbs Free Energy Equation: T

T = absolute temperature

ΔG of ATP

= -7.3kcal/mol

Exergonic reactions havea + or - ΔG

•  Reactions that release energy have a negative ΔG

  • Spontaneous: No energy inputted

  • Catabolic: breaks down molecules (this is how cells provide the energy needed for endergonic reactions)

Endergonic reactions have a + or - ΔG

Reactions that absorb energy have a positive ΔG

• Energy is inputted

• Anabolic: makes  molecules

What is activation energy E_a

 the amount of energy needed for a reaction to start

• Impacts reaction rate

What is reaction rate?

measures how fast the reaction happens

• Dependent on: temperature, concentration, and activation energy

what are catalysts

 enzymes that lower activation energy

What are substrates

reactants/starting molecules

• Enzymes bind to the active site of the substrate

• Substrate changes shape once enzymes bind to it

Enzymes are…

• Highly specific: they have a specific shape that allows them to only bind with a specific substrate

• Reusable: can use them for reactions over and over again

• Used in small amounts

• Can be more than just proteins

What is the induced fit model?

 each enzyme has a specific shape (lock) that allows a substrate (key) to fit and bind at the active site

Denaturation of enzymes:

• temperature

• pH

• concentration

Denaturation of enzymes: Temperature graph

optimal temp

Denaturation on Enzymes: pH

optimal pH

Denaturation of Enzymes: Substrate concentration

max concentration