Biology 20A – Cell and Molecular Biology

These flashcards cover key concepts from the lecture notes on Cell and Molecular Biology, focusing on biochemistry, macromolecules, and cellular processes.

What is the predominant atom found in a typical cell and what is its valence?

The predominant atoms are Carbon, Oxygen, Hydrogen, and Nitrogen with various valences (Carbon: 4, Oxygen: 2, Hydrogen: 1, Nitrogen: 3).

Explain the difference between polar and nonpolar covalent bonds.

Polar covalent bonds occur when electrons are unequally shared between atoms, creating a dipole; nonpolar covalent bonds occur when electrons are equally shared.

What allows molecules to interact via hydrogen bonding?

The existence of polar covalent bonds allows molecules to interact through hydrogen bonding.

Why is water considered an ideal solvent for biological systems?

Water is an ideal solvent because it can form hydrogen bonds, which facilitates the dissolving of many substances.

What does the pH scale indicate in relation to proton concentration?

The pH scale indicates the concentration of hydrogen ions (protons) in a solution; lower pH means higher proton concentration.

What are the major classes of biological macromolecules?

The major classes of biological macromolecules are proteins, carbohydrates, nucleic acids, and lipids.

What is the role of buffers in biological systems?

Buffers help maintain stable pH levels in biological systems despite the addition of acids or bases.

What are the three components of nucleotides?

The three components of nucleotides are a nitrogenous base, a pentose sugar, and one or more phosphate groups.

What is the function of ATP in cells?

ATP functions as the 'energy currency' of the cell, providing energy for various biochemical processes.

What distinguishes prokaryotic cells from eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a defined nucleus and organelles.

Describe the function of enzymes in biochemical reactions.

Enzymes increase the rate of biochemical reactions by lowering the activation energy required for the reaction.

What are the main stages of the eukaryotic cell cycle?

The main stages are G1 (growth), S (DNA synthesis), G2 (preparation for mitosis), and M (mitosis).

Explain the different levels of protein structure.

The levels of protein structure are primary (amino acid sequence), secondary (alpha helices and beta sheets), tertiary (3D shape), and quaternary (multiple polypeptide chains).

How do saturated and unsaturated fatty acids differ in their impact on fluidity of fats and oils?

Saturated fatty acids are solid at room temperature and less fluid, while unsaturated fatty acids are liquid at room temperature and increase fluidity.

What is the significance of the sodium-potassium ATPase in cells?

The sodium-potassium ATPase maintains the electrical potential across the plasma membrane by pumping sodium out and potassium into the cell.