General Biology Study Notes: Science Practices and Biological Molecules

Science Practices in Biology

Overview of Science Practices

Mastery of science practices is essential for success in college-level biology. These practices encompass the skills needed to analyze, interpret, and communicate biological concepts and data.

• Concept Explanation: Clearly explain biological concepts, processes, and models in written format.

• Visual Representations: Analyze and construct visual representations such as diagrams, mathematical models, and flow charts to illustrate biological concepts and processes.

• Questions and Methods:

  • Identify and pose testable questions based on observations, data, or models.

  • State null and alternative hypotheses, and predict results of experiments.

  • Design experiments, including identification of dependent and independent variables and appropriate controls.

  • Make observations and collect data from laboratory setups or results.

  • Propose new investigations based on evaluation of previous experiments or results.

• Representing and Describing Data:

  • Construct graphs, plots, or charts with correct orientation, labeling, units, scaling, and trend lines.

  • Be able to describe and interpret data representations, including patterns, trends, and relationships.

• Statistical Tests and Data Analysis:

  • Perform mathematical calculations such as means, rates, ratios, and percentages.

  • Use confidence intervals and/or error bars to determine statistical significance.

  • Perform Chi-square hypothesis testing.

  • Use data to evaluate hypotheses.

• Argumentation:

  • Make scientific claims and support them with evidence from biological principles, concepts, and data.

  • Connect claims to scientific theories.

  • Explain relationships between data and larger biological concepts or theories.

  • Predict causes or effects of changes in biological systems.

Properties of Water and Biological Function

Water's Role in Biology

Water is a vital molecule in biological systems due to its unique properties, which affect biological function and structure.

• Polarity: Water is a polar molecule, meaning it has a partial positive charge on one side and a partial negative charge on the other, allowing it to form hydrogen bonds.

• Cohesion and Adhesion: Cohesion refers to water molecules sticking to each other, while adhesion refers to water molecules sticking to other surfaces.

• Surface Tension: The cohesive forces at the surface of water create surface tension, which allows small objects to rest on water without sinking.

• High Specific Heat: Water can absorb or release large amounts of heat with little temperature change, helping to stabilize environments.

• Solvent Properties: Water's polarity makes it an excellent solvent for ionic and polar substances, facilitating biochemical reactions.

Example: Water's ability to dissolve salts and sugars is crucial for cellular processes and transport in living organisms.

Elements and Macromolecules in Living Systems

Major Elements and Macromolecules

Living organisms are composed of a limited number of elements and macromolecules that provide energy and structural support.

• Major Elements: Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur are the primary elements found in biological molecules.

• Macromolecules: The four major classes are carbohydrates, lipids, proteins, and nucleic acids.

• Energy and Structure: Macromolecules are involved in energy storage, structural support, and the regulation of biological processes.

Example: Glucose (a carbohydrate) is a primary energy source for cells.

Types of Biological Macromolecules

Carbohydrates, Lipids, Proteins, and Nucleic Acids

Biological macromolecules are large, complex molecules essential for life. Each type has distinct structures and functions.

• Carbohydrates: Composed of carbon, hydrogen, and oxygen. Serve as energy sources and structural components. Example: Starch, cellulose.

• Lipids: Include fats, oils, and phospholipids. Important for energy storage, membrane structure, and signaling. Example: Triglycerides, phospholipids.

• Proteins: Made of amino acids. Function as enzymes, structural components, and signaling molecules. Example: Hemoglobin, enzymes.

• Nucleic Acids: DNA and RNA store and transmit genetic information. Composed of nucleotides. Example: DNA, RNA.

Example: Phospholipids form the bilayer of cell membranes, providing a barrier and functional interface for cellular processes.

Formation and Breakdown of Macromolecules

Synthesis and Hydrolysis Reactions

Macromolecules are formed and broken down through specific chemical reactions that involve the addition or removal of water.

• Dehydration Synthesis (Condensation): Monomers are joined to form polymers by removing a water molecule.

• Hydrolysis: Polymers are broken down into monomers by adding a water molecule.

• Functional Groups: The properties and reactivity of macromolecules are influenced by functional groups such as hydroxyl, carboxyl, amino, and phosphate groups.

Example: The formation of a peptide bond between two amino acids involves dehydration synthesis.

Classification and Structure of Biological Macromolecules

Detailed Overview of Macromolecule Types

Each class of biological macromolecule has unique structural features and functions.

• Carbohydrates:

  • Monosaccharides (simple sugars), disaccharides, and polysaccharides (complex carbohydrates).

  • Structural differences determine function (e.g., starch vs. cellulose).

• Lipids:

  • Composed of fatty acids and glycerol.

  • Types include triglycerides, phospholipids, and steroids.

  • Phospholipids have hydrophilic heads and hydrophobic tails, forming cell membranes.

• Nucleic Acids:

  • DNA and RNA are polymers of nucleotides.

  • DNA stores genetic information; RNA is involved in protein synthesis.

• Proteins:

  • Polymers of amino acids linked by peptide bonds.

  • Structure determines function: primary, secondary, tertiary, and quaternary levels.

Example: Enzymes are proteins that catalyze biochemical reactions, increasing reaction rates without being consumed.

Comparison Table: Major Biological Macromolecules

Macromolecule	Monomer	Function	Example
Carbohydrate	Monosaccharide	Energy source, structure	Glucose, cellulose
Lipid	Fatty acid, glycerol	Energy storage, membrane structure	Triglyceride, phospholipid
Protein	Amino acid	Enzymes, structure, signaling	Hemoglobin, enzyme
Nucleic Acid	Nucleotide	Genetic information storage, protein synthesis	DNA, RNA

Key Equations

• Dehydration Synthesis: $\text{Monomer}_1 + \text{Monomer}_2 \rightarrow \text{Polymer} + \text{H}_2\text{O}$

• Hydrolysis: $\text{Polymer} + \text{H}_2\text{O} \rightarrow \text{Monomer}_1 + \text{Monomer}_2$

Additional info: Academic context and definitions have been expanded for clarity and completeness.