Lecture 1 Flashcards
Bond Strength
Energy needed to break a bond
Covalent bonds vs Non covalent?
Covalent bonds are 1000X stronger
How are covalent bonds broken?
By chemical reactions
Why are macromolecules made up of covalent bonds?
Crowded cell environment and aqueous environment means the molecules must stay intact
99% of the cell is made up of ?
C, N, H, O
0.9% of the cell is made up of ?
Mg, P, S, Cl, Na, K, Ca
What are chemical groups?
Ex. Methyl, Hydroxyl, Carboxyl, Carbonyl
These come together to make macromolecules
Why do molecules in our cells rely on carbon ?
- Carbon can form four covalent bonds with other atoms
- When carbons bind to other carbons they can form various shapes which means various functions
- Form organic compounds
What is an organic compound?
Carbon based compounds that are found in an aqueous environment
Four main types of carbon compounds?
- Sugar
- Amino Acid
- Fatty Acid
- Nucleotide
What are the uses of organic molecules ?
- Used as monomers to create polymers
- Energy sources (covelent bonds store energy for metabolic pathways)
Macromolecule of each organic molecule?
Amino acid —– Protein
Sugar —– Polysaccharide
Nucleotide —– Nucleic Acids (DNA + RNA)
Fatty Acids —- Fats + membrane lipids
What makes up the majority of the chemicals in a cell and what are its two functions?
Protein
1. Gives shape to the cell
2. Main functional unit (ex. enzymes)
Covalent vs non Covalent bonds in terms of flexibility?
Covalent : Allow rotation and allow the macromolecule to have multiple conformations
Non-covalent: Do not allow free rotation, the macromolecule is contrained to one shape
Living cells vs Non living
Living cells = create and maintain order by performing never ending chemicalc reactions
Non-living cells = Tend to greater disorder
Anabolic Reaction + Example
Reaction that requires energy to make a macromolecule
Ex. Condensation. This reaction is energetically unfavorable and causes the release of H2O
Catabolic Reaction + Example
Reaction that is energetically favourable and is th ebreaking of covelent bonds that releases energy
Ex. Hydrolysis. Water is added to a molecule to break the covalent bonds
Second Law of Thermodynamics?
In an isolated system the degree of disorder always increases
“Spontaneous reaction”
Larger entropy
What is Entropy?
Amount of disorder
Large entropy = Large disorder
Are cells isolated systems ?
No, the cell is made up of the cell + the external environment. Which means total entropy increases within the cell + external environment
How do cells generate order?
Cells undergo chemical reactions within them to generate order. These reactions release heat which causes the external environment of the cell to be disordered
Where does heat come from in cells?
When macromolecules are broken down in cells(catabolic), heat is released into the environment unless it is needed for the creation of more macromolecules within the cell
First law of thermodynamics?
Energy can be converted from one form to another but it cannot be created or destroyed
Describe first law of thermodynamics in terms of humans and plants?
Plants convert light energy into chemical energy through photosynthesis which creates covalent bonds in glucose. Humans then use that chemical energy to create macromolecules.
Enthalpy (H)
Amount of energy that can be released from chemical bonds
Negative Enthalpy?
Spontaneous and energetically favourable reaction
Gibbs Free Energy Equation
Delta G = delta H - T(deltaS)
High temperature and increased disorder means?
Spontaneous reaction if T(delta S) is greater than delta H. More disorder means a loss of free energy
WHat do enzymes do ?
Lower the activation energy of a chemical reaction, this helps speed up the reaction lowers delta G
How do enzymes affect energetically unfavourable reactions?
They cannot force these reactions to occur and therefore enzymes do not affect the reaction
Coupling of reactions in cells?
- Food moelcules are broken down into their organic compounds (catabolic) this releases energyy
- This energy is then used by anabolic reactions such as by reactions to create more macromolecules in the cell
Most used activated energy carrier?
ATP
Where is energy stored in ATP ?
THe three phosphate bonds
Steps of an ATP driven reaction?
- Activation : ATP adds a phosphate onto one of the reactants to create a high energy intermediate
- Condensation: The high energy intermediate interacts with the other reactant to form a covalent bond and release the inorganic phosphate
Acetyl CoA?
Another type of energy carrier that carries energy in a thioester bond
Equilibrium?
When the reactants and products of a reaction are present in concentrations where they tend to stay relatively constant and the net flow of both reactions is constant
Describe how equilibrium is reached?
Ex. IF delta G from Y to X is negative then conversion from Y to X will be spontaneous occur often. Conversion from X to Y will occur less. However eventually there will be so much X that the rate at which molecules of Y are converted to X and molecules of X to Y will be equal
Oxidation vs Reduction?
Oxidation: Removal of electrons from an atom (partially positive)
Reduction: Addition of electrons from an atom (partially negative)
Hydrogenation?
When a molecule is reduced it usually always also picks up a hydrogen
Electron carriers?
NADH and NADPH (these are reduced)
