General Biology Study Notes: Biomolecules, Macromolecules, and Scientific Skills

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Biomolecules and Chemical Bonds

Water Molecules and Hydrogen Bonding

Water is a polar molecule, meaning it has a partial positive charge on one side and a partial negative charge on the other. This polarity allows water molecules to form hydrogen bonds with each other and with other substances.

Hydrogen Bond: A weak bond formed between a hydrogen atom in one molecule and an electronegative atom (such as oxygen or nitrogen) in another molecule.
Cohesion: The attraction between molecules of the same substance (e.g., water molecules sticking together).
Adhesion: The attraction between molecules of different substances (e.g., water molecules sticking to glass).
Surface Tension: The result of cohesion at the surface of a liquid, allowing it to resist external force.
Example: Water droplets forming beads on a leaf due to surface tension.

Additional info: Hydrogen bonds are crucial for the properties of water, such as its high specific heat and solvent abilities.

Macromolecules

Categories and Monomers

Macromolecules are large, complex molecules essential for life. They are built from smaller units called monomers.

Four Main Categories:
1. Carbohydrates (monomer: monosaccharides)
2. Lipids (monomer: fatty acids and glycerol)
3. Proteins (monomer: amino acids)
4. Nucleic Acids (monomer: nucleotides)
Polymerization: The process of joining monomers to form polymers.
Directionality: Refers to the orientation of the monomers in a polymer chain (e.g., 5' to 3' in nucleic acids).
Example: Starch is a carbohydrate polymer made of glucose monomers.

Additional info: Macromolecules differ in their structure and function based on the type and arrangement of their monomers.

Hydrolysis and Dehydration Synthesis

Macromolecules are assembled and broken down by specific chemical reactions.

Dehydration Synthesis: The process of joining two monomers by removing a water molecule.
Hydrolysis: The process of breaking a polymer into monomers by adding a water molecule.
Equation for Dehydration Synthesis:

Equation for Hydrolysis:

Macromolecule Comparison Table

The following table summarizes the four main types of macromolecules, their monomers, and functions.

Macromolecule	Monomer	Function
Carbohydrates	Monosaccharides	Energy storage, structural support
Lipids	Fatty acids & glycerol	Energy storage, membrane structure
Proteins	Amino acids	Catalysis, structure, transport
Nucleic Acids	Nucleotides	Genetic information storage & transfer

Proteins

Amino Acids and R Groups

Proteins are polymers made of amino acids. Each amino acid has a central carbon, an amino group, a carboxyl group, and a unique side chain called an R group.

R Group: The variable side chain that determines the properties and function of each amino acid.
Example: Glycine has a hydrogen as its R group, while glutamic acid has a carboxyl group.
Additional info: The chemical nature of the R group (polar, nonpolar, acidic, basic) affects protein folding and function.

Levels of Protein Structure

Proteins have four levels of structure, each contributing to their overall shape and function.

Primary Structure: The sequence of amino acids in a polypeptide chain.
Secondary Structure: Local folding patterns such as alpha helices and beta sheets, stabilized by hydrogen bonds.
Tertiary Structure: The overall three-dimensional shape of a single polypeptide, determined by interactions among R groups.
Quaternary Structure: The association of multiple polypeptide chains to form a functional protein.
Example: Hemoglobin has a quaternary structure composed of four polypeptide subunits.

Nucleic Acids

DNA vs. RNA

DNA and RNA are nucleic acids that store and transmit genetic information. They differ in structure and function.

DNA: Double-stranded, contains deoxyribose sugar, uses thymine as a base.
RNA: Single-stranded, contains ribose sugar, uses uracil as a base.
Function: DNA stores genetic information; RNA is involved in protein synthesis and gene regulation.
Example: Messenger RNA (mRNA) carries genetic instructions from DNA to ribosomes.

Scientific Skills

Claim, Evidence, Reasoning (CER)

The CER framework is used to construct scientific explanations.

Claim: A statement or conclusion that answers a question.
Evidence: Scientific data that supports the claim.
Reasoning: The justification that links the evidence to the claim using scientific principles.
Example: "Claim: Water is essential for life. Evidence: All known living organisms require water. Reasoning: Water's properties as a solvent enable biochemical reactions necessary for life."

Graphing and Data Analysis

Graphs are used to visualize scientific data and identify patterns.

Bar Graph: Used for comparing discrete categories.
Line Graph: Used for showing changes over time or continuous data.
Independent Variable: The variable that is changed or controlled in an experiment.
Dependent Variable: The variable that is measured or observed.
Example: Plotting temperature (independent variable) vs. enzyme activity (dependent variable).

Hypotheses and Alternative Hypotheses

Scientific investigations begin with hypotheses, which are testable statements about the natural world.

Hypothesis: A proposed explanation for an observation, which can be tested by experimentation.
Alternative Hypothesis: A different explanation that can also be tested.
Supporting Hypotheses: Use evidence from experiments to support or refute hypotheses.
Example: "If plants receive more sunlight, then they will grow taller."

Data Table Construction and Analysis

Data tables organize information for analysis and interpretation.

Key Elements: Title, labeled columns and rows, units of measurement.
Example Table:

Sample	Sunlight (hours)	Plant Height (cm)
1	4	12
2	8	20
3	12	28

Additional info: Data tables should be clear and allow for easy comparison and analysis of results.