General Biology: Atomic Structure, Chemical Bonds, Macromolecules, and Experimental Design

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Chapter 2: Atomic Structure and Chemical Bonds

Subatomic Particles and Isotopes

Atoms are composed of three main subatomic particles: protons, neutrons, and electrons. These particles determine the identity and properties of each element.

Proton: Positively charged particle found in the nucleus. The number of protons defines the atomic number and the element.
Neutron: Neutral particle found in the nucleus. The number of neutrons can vary, resulting in different isotopes of the same element.
Electron: Negatively charged particle found in orbitals around the nucleus.
Isotope: Atoms of the same element with different numbers of neutrons. Example: Carbon-12 and Carbon-14 are isotopes of carbon.
Calculating Neutrons:

Types of Chemical Bonds

Chemical bonds form when atoms interact to achieve stable electron configurations. The main types are ionic, covalent, and hydrogen bonds.

Ionic Bond: Formed when electrons are transferred from one atom to another, resulting in oppositely charged ions that attract each other. Example: NaCl (sodium chloride)
Covalent Bond: Formed when two atoms share one or more pairs of electrons. Example: H2O (water)
Hydrogen Bond: A weak bond between a hydrogen atom covalently bonded to an electronegative atom (like oxygen) and another electronegative atom.

Electron Configuration and Periodic Table

Electron configuration describes the arrangement of electrons in an atom's orbitals. This determines chemical reactivity and bonding.

Valence Electrons: Electrons in the outermost shell, important for bonding.
Electron Distribution Diagrams: Visual representations of electron arrangement.
Periodic Table: Organized by atomic number; elements in the same group have similar valence electron configurations.

Polarity of Covalent Bonds

Covalent bonds can be polar or nonpolar depending on the difference in electronegativity between the atoms involved.

Polar Covalent Bond: Electrons are shared unequally, resulting in partial charges. Example: H2O
Nonpolar Covalent Bond: Electrons are shared equally. Example: O2

Chapter 3: Water and Its Properties

Types of Bonds in Water Molecules

Water molecules are held together by polar covalent bonds, and multiple water molecules interact via hydrogen bonds.

Polar Covalent Bonds: Hold the hydrogen and oxygen atoms together within a single water molecule.
Hydrogen Bonds: Form between the hydrogen of one water molecule and the oxygen of another, leading to unique properties.

Emergent Properties of Water

Water exhibits several unique properties due to hydrogen bonding:

Cohesion: Water molecules stick together, aiding in transport in plants.
Adhesion: Water molecules stick to other substances.
High Specific Heat: Water resists temperature changes, stabilizing environments.
High Heat of Vaporization: Requires significant energy to change from liquid to gas.
Expansion Upon Freezing: Ice is less dense than liquid water.

pH Scale and Acidity

The pH scale measures the concentration of hydrogen ions in a solution, indicating its acidity or alkalinity.

pH Scale: Ranges from 0 (most acidic) to 14 (most basic), with 7 being neutral.
Calculating pH:
Acidic Solution: pH < 7
Basic Solution: pH > 7
Example: If a solution has [H+] = 1 x 10-4 M, then pH = 4.

Chapter 4: Carbon and Molecular Diversity

Valence Electrons and Bonding

Carbon has four valence electrons, allowing it to form up to four covalent bonds with other atoms, leading to a diversity of organic molecules.

Valence Electrons: Electrons available for bonding in the outer shell.
Bonding Capacity: Carbon's four valence electrons allow for complex molecules.

Functional Groups

Functional groups are specific groups of atoms within molecules that have characteristic properties and chemical reactivity.

Common Functional Groups: Hydroxyl (-OH), carbonyl (C=O), amino (-NH2), phosphate (-PO4), carboxyl (-COOH).
Role: Determine the properties and reactions of organic molecules.

Isomers

Isomers are molecules with the same molecular formula but different \

structures and properties.

Structural Isomers: Differ in the covalent arrangement of atoms.
Cis-Trans Isomers: Differ in spatial arrangement around double bonds.
Enantiomers: Mirror images of each other, important in biology.

Chapter 5: Macromolecules and Biochemistry

Dehydration and Hydrolysis Reactions

Macromolecules are formed and broken down by specific chemical reactions.

Dehydration Reaction: Joins monomers by removing a water molecule.
Hydrolysis Reaction: Breaks polymers into monomers by adding water.

Types of Organic Compounds

There are four major classes of organic macromolecules in living organisms:

Carbohydrates: Sugars and starches, provide energy and structural support.
Lipids: Fats, oils, and phospholipids, important for energy storage and membranes.
Proteins: Polymers of amino acids, perform a wide range of functions.
Nucleic Acids: DNA and RNA, store and transmit genetic information.

Carbohydrates: Structure and Classification

Carbohydrates can be classified based on the number of sugar units:

Monosaccharides: Single sugar units (e.g., glucose).
Disaccharides: Two monosaccharides joined (e.g., sucrose).
Polysaccharides: Long chains (e.g., starch, cellulose).

Fats: Saturated vs. Unsaturated

Fats are classified based on the presence of double bonds in their fatty acid chains.

Saturated Fats: No double bonds, solid at room temperature.
Unsaturated Fats: One or more double bonds, liquid at room temperature.

Proteins: Structure and Function

Proteins have four levels of structure that determine their function:

Primary Structure: Sequence of amino acids.
Secondary Structure: Local folding (alpha helices, beta sheets).
Tertiary Structure: Overall 3D shape.
Quaternary Structure: Association of multiple polypeptides.

Nucleic Acids: Components

Nucleic acids are polymers of nucleotides, each consisting of:

Phosphate group
Pentose sugar (deoxyribose in DNA, ribose in RNA)
Nitrogenous base (adenine, thymine, cytosine, guanine, uracil)

Experimental Design and Data Analysis

Variables and Groups

Experimental design involves identifying variables and control/treatment groups.

Independent Variable: The factor that is changed or manipulated.
Dependent Variable: The factor that is measured.
Control Group: The group that does not receive the experimental treatment.
Experimental Group: The group that receives the treatment.

Protein Function and Amino Acid Sequence

Changes in the amino acid sequence of a protein can alter its structure and function, potentially leading to loss of function or disease.

Example: Sickle cell anemia is caused by a single amino acid substitution in hemoglobin.

Graphing and Data Analysis

Data from experiments are often represented in graphs to visualize relationships and differences.

Generating Graphs: Plotting data points to show trends or comparisons.
Analyzing Graphs: Interpreting relationships, statistical differences, and drawing conclusions.