Bio98CLec1-25

What is the Central Dogma of Biology?

The Central Dogma of Biology describes the flow of genetic information from DNA to RNA to protein.

What are the four bases of DNA?

The four bases of DNA are deoxyadenosine (dA), deoxythymidine (dT), deoxyguanosine (dG), and deoxycytidine (dC).

What are the four bases of RNA?

The four bases of RNA are adenine (A), uracil (U), guanine (G), and cytosine (C).

What is the function of enzymes?

Enzymes are proteins that catalyze all chemical reactions.

What is the difference between hydrophilic and hydrophobic molecules?

Hydrophilic molecules are 'water-loving' and can interact with water, while hydrophobic molecules are 'water-fearing' and do not interact favorably with water.

What unusual property of water allows life to depend on it?

Water is the only substance on Earth that naturally exists in all three physical states: solid, liquid, and gas.

What is the relationship between Gibbs Free Energy change (DG) and spontaneity of a reaction?

If DG is negative, the reaction is spontaneous; if DG is positive, the reaction is non-spontaneous.

What are non-covalent interactions and their significance?

Non-covalent interactions are weaker, dynamic forces important for biological processes like DNA and protein interactions.

What is an amphipathic molecule?

An amphipathic molecule has both a hydrophilic (water-attracting) and a hydrophobic (water-repelling) part.

How do hydrophobic interactions occur?

Hydrophobic interactions occur due to the coalescence of non-polar molecules in water, driven by the stability of the surrounding water's hydrogen bonding.

What are the two laws of thermodynamics?

1. Energy cannot be created or destroyed

2. The entropy of the universe always increases.

Define covalent bonds in terms of strength.

Covalent bonds are strong bonds with energy ranging from 250-800 kJ/mol.

What is the role of ATP in metabolism?

ATP provides energy to drive unfavorable metabolic reactions.

Which type of non-covalent interaction is highly directional and involves fixed length?

Hydrogen bonds are highly directional and have a fixed length of 2.5Å - 3.5Å.

What effect does water have on hydrophobic molecules?

Water forms an ordered structure around hydrophobic molecules, making it energetically unfavorable for them to mix.

How does the concentration of reactants and products affect free energy (DG)?

DG can change based on the concentrations of the reactants and products, indicating the favorability of the reaction direction.

Name the four types of non-covalent interactions.

1. Charge-charge (ionic) interactions; 2. Hydrogen bonds; 3. Van der Waals forces; 4. Hydrophobic interactions.

What is meant by a process being spontaneous in relation to the equilibrium constant (Keq)?

If Keq > 1.0, the reaction moving to the right is favored, indicating that the products are favored over the reactants.

What defines a weak bond in biochemistry?

Weak bonds include non-covalent bonds, which typically have energies ranging from 0.4-250 kJ/mol.

What are ionic interactions?

Ionic interactions are non-directional and distance dependent, occurring between oppositely charged molecules or ions that can be either attractive or repulsive, with energy ranging from 6 to 250 kJ mol-1.

What are Hydrogen Bonds?

Hydrogen bonds are non-covalent interactions that occur between a hydrogen atom covalently bonded to a more electronegative atom (like oxygen or nitrogen) and another electronegative atom. These bonds are highly directional and typically have a fixed length of 2.5Å - 3.5Å.

What is the significance of hydrogen bonds in biology?

Hydrogen bonds are crucial for the structure and function of biomolecules, influencing protein folding, DNA base pairing, and the properties of water.

How do hydrogen bonds compare in strength to covalent bonds?

Hydrogen bonds are significantly weaker than covalent bonds, generally with energies ranging from 2 to 10 kJ/mol.

What factors influence the strength of hydrogen bonds?

The strength of hydrogen bonds is influenced by the electronegativity of the atoms involved and the environment in which they occur.

In what type of biomolecules are hydrogen bonds commonly found?

Hydrogen bonds are commonly found in nucleic acids (like DNA and RNA) and proteins, playing a key role in their structure and stability.

What are Van der Waals forces?

Van der Waals forces are the weakest of the non-covalent interactions, arising from permanent, transient, or induced dipoles that can occur in all molecules. These forces typically range from 0.4 to 4 kJ mol-1.

What is the significance of Gibbs Free Energy change (ΔG) in chemical reactions?

Gibbs Free Energy change (ΔG) is an indicator of reaction spontaneity: if ΔG is negative, the reaction proceeds spontaneously, while a positive ΔG indicates the reaction is non-spontaneous.

How can the concentrations of reactants and products impact Gibbs Free Energy (ΔG)?

The concentrations of reactants and products affect Gibbs Free Energy (ΔG), indicating the direction in which the reaction is favored.

What does the equilibrium constant (K_eq) indicate about a reaction's spontaneity?

A K_eq greater than 1.0 implies that the reaction is favored towards product formation, indicating spontaneous behavior in that direction.

What is the formula for calculating Gibbs Free Energy change (ΔG)?

ΔG can be calculated using the formula ΔG = ΔGºproducts - ΔGºreactants, where a spontaneous reaction has ΔG < 0 due to Gºreactants being greater than Gºproducts.

What does ΔG represent in thermodynamics?

ΔG represents the change in free energy that occurs when transitioning from reactants to products, enabling the assessment of the process's spontaneity.

What is the difference between ΔG and ΔGº?

ΔG represents the change in free energy under specific conditions, while ΔGº denotes the standard free energy change at standard conditions (1 M concentration, 1 atm pressure, and 25°C).

What Equation is used to find Gibbs Free Energy change (ΔG)?

The equation for calculating ΔG is ΔG = ΔGº + RT ln(Q), where Q is the reaction quotient, R is the ideal gas constant, and T is the temperature in Kelvin. This equation allows for the determination of Gibbs Free Energy under non-standard conditions.