Cell Biology Exam 1 Study Guide: Key Concepts and Topics

Preview of the Cell

Term 'cell' and Cell Theory

The cell is the fundamental unit of life, forming the basis of all living organisms. Cell theory states that all living things are composed of cells, cells are the basic units of structure and function, and all cells arise from pre-existing cells.

• Three branches of modern cell biology: Cytology, Biochemistry, Genetics

• Cytology: Study of cell structure and function using microscopy

Cell Instrumentation

• Light Microscopy: Uses visible light to observe cells; includes bright-field, phase-contrast, and fluorescence microscopy

• Electron Microscopy: Uses electron beams for higher resolution; includes transmission (TEM) and scanning (SEM) types

• Biochemical Methods: Techniques for analyzing cell components, such as centrifugation and chromatography

Genetics and Model Systems

• Classical Genetics: Study of inheritance and gene function

• Molecular Genetics: Focuses on DNA, RNA, and protein synthesis

• Model Systems: Organisms like Escherichia coli, yeast, and mice used for research due to their simplicity and relevance

The Chemistry of the Cell

Characteristics of Carbon

Carbon is the backbone of biological molecules due to its ability to form four covalent bonds, allowing for complex structures.

• Bond Polarity: Determines molecule interactions and solubility

• Stability: Carbon bonds are stable, enabling large macromolecules

Water and Its Properties

• Polarity: Water is a polar molecule, facilitating hydrogen bonding

• Temperature-Stabilizing Capacity: High specific heat helps maintain cellular temperature

• Solvent Properties: Water dissolves many substances, supporting cellular reactions

Membranes and Small Molecules

• Permeability: Membranes selectively allow passage of molecules

• Self-Assembly: Lipids and proteins spontaneously form membranes

The Macromolecules of the Cell

Polymer Hierarchy

• Monomers: Building blocks (amino acids, nucleotides, monosaccharides)

• Polymers: Proteins, nucleic acids, polysaccharides

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose)

• Disaccharides: Two monosaccharides joined (e.g., sucrose)

• Polysaccharides: Long chains (e.g., starch, glycogen, cellulose)

Lipids

• Classes: Fatty acids, triglycerides, phospholipids, steroids

• Functions: Energy storage, membrane structure, signaling

Proteins

• Amino Acids: 20 standard types, each with a unique side chain

• Peptide Bonds: Link amino acids in a protein

• Levels of Organization: Primary (sequence), secondary (α-helix, β-sheet), tertiary (3D folding), quaternary (multiple polypeptides)

• Protein Domains: Functional regions within proteins

Nucleic Acids

• DNA and RNA: Polymers of nucleotides; DNA stores genetic information, RNA is involved in protein synthesis

Bioenergetics: The Flow of Energy in the Cell

Cellular Energy and Thermodynamics

Cells obey the laws of thermodynamics, converting energy for biological work.

• First Law: Energy cannot be created or destroyed

• Second Law: Entropy (disorder) increases in closed systems

Free Energy and Cellular Reactions

• Gibbs Free Energy ($G$): Determines spontaneity of reactions

• Equation: $\Delta G = \Delta H - T\Delta S$

• Standard Free Energy Change ($\Delta G^\circ$): Calculated under standard conditions

Equilibrium and Reaction Coupling

• Equilibrium Constant ($K_{eq}$): Ratio of product to reactant concentrations at equilibrium

• Coupled Reactions: Unfavorable reactions can proceed by coupling to favorable ones

Oxidation and Reduction

• Oxidation: Loss of electrons

• Reduction: Gain of electrons

• Redox Reactions: Central to energy metabolism

Table: Classes and Functions of Macromolecules

Macromolecule	Monomer	Function
Proteins	Amino acids	Catalysis, structure, signaling
Nucleic Acids	Nucleotides	Genetic information, protein synthesis
Polysaccharides	Monosaccharides	Energy storage, structure
Lipids	Fatty acids	Membranes, energy storage, signaling

Additional info:

• Some details inferred from standard cell biology curriculum, such as the role of model organisms and the importance of protein domains.

• Equations and definitions expanded for clarity and completeness.