General Biology Exam Study Guide: Chemistry of Life, Macromolecules, and Water

Study Guide - Smart Notes

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This section covers foundational chemistry concepts essential for understanding biological molecules and processes.

Definition and Examples of Matter: Matter is anything that has mass and occupies space. Examples include solids, liquids, and gases.
Elements and Compounds: Elements are pure substances consisting of only one type of atom. Compounds are substances formed from two or more elements chemically bonded together.
Atoms and Atomic Structure: Atoms consist of protons, neutrons, and electrons. Atomic number refers to the number of protons; atomic mass is the sum of protons and neutrons.
Properties of Elements: Elements are characterized by their atomic number, mass, and chemical properties.
Isotopes: Isotopes are atoms of the same element with different numbers of neutrons. Some isotopes are radioactive and have applications in medicine and research.
Electron Shells and the Octet Rule: Electrons occupy energy levels (shells) around the nucleus. The octet rule states that atoms tend to gain, lose, or share electrons to achieve eight electrons in their outer shell.
Ions: Ions are charged atoms or molecules formed by the loss or gain of electrons. Cations are positively charged; anions are negatively charged.
Covalent and Ionic Bonding: Covalent bonds involve the sharing of electron pairs between atoms. Ionic bonds result from the transfer of electrons from one atom to another.
Polar and Nonpolar Covalent Bonds: Polar covalent bonds have unequal sharing of electrons, leading to partial charges. Nonpolar covalent bonds share electrons equally.

Example: Water (H2O) is a polar molecule due to the unequal sharing of electrons between hydrogen and oxygen.

Water is essential for life due to its unique chemical and physical properties.

Hydrogen Bonding: Hydrogen bonds are weak attractions between the partially positive hydrogen atom of one molecule and the partially negative atom (often oxygen or nitrogen) of another.
Solvent Properties: Water is a universal solvent, able to dissolve many substances due to its polarity.
Hydrophobic vs. Hydrophilic: Hydrophilic substances interact well with water; hydrophobic substances do not.
Solutes and Solvents: A solute is dissolved in a solvent to form a solution. Water is often the solvent in biological systems.

Example: Salt (NaCl) dissolves in water because the polar water molecules surround and separate the ions.

Carbon is the backbone of organic molecules due to its ability to form four covalent bonds.

Covalent Bonds: Carbon forms stable covalent bonds with other atoms, allowing for complex molecules.
Dynamic Molecules: Carbon's versatility leads to a variety of molecular shapes and functions.
Functional Groups: Functional groups are specific groups of atoms within molecules that confer particular chemical properties. Key groups include hydroxyl, carbonyl, carboxyl, amino, phosphate, and methyl.

Example: The hydroxyl group (-OH) is found in alcohols and increases solubility in water.

Macromolecules are large, complex molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids.

Monomers and Polymers: Monomers are small building blocks that join to form polymers through chemical reactions.
Dehydration and Hydrolysis Reactions: Dehydration synthesis joins monomers by removing water; hydrolysis breaks polymers into monomers by adding water.

Example: Glucose monomers join to form starch via dehydration synthesis.

Carbohydrates are energy-rich organic compounds made of carbon, hydrogen, and oxygen.

Monosaccharides: Simple sugars like glucose and fructose. They are the monomers of carbohydrates.
Disaccharides: Formed by joining two monosaccharides (e.g., sucrose, lactose).
Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).
Biological Importance: Polysaccharides serve as energy storage (starch, glycogen) and structural materials (cellulose).

Example: Glycogen is the storage form of glucose in animals.

Lipids are hydrophobic molecules important for energy storage, membrane structure, and signaling.

Types of Lipids: Includes fats, oils, phospholipids, and steroids.
Fatty Acids: Long hydrocarbon chains with a carboxyl group. Saturated fatty acids have no double bonds; unsaturated have one or more.
Triglycerides: Formed by joining three fatty acids to a glycerol molecule.
Phospholipids: Major component of cell membranes; have hydrophilic heads and hydrophobic tails.
Biological Functions: Energy storage, insulation, and membrane structure.

Example: Phospholipids form the bilayer of cell membranes.

Lipid Type	Structure	Function
Triglyceride	Glycerol + 3 fatty acids	Energy storage
Phospholipid	Glycerol + 2 fatty acids + phosphate group	Cell membrane structure
Steroid	Four fused rings	Hormones, signaling

Proteins are polymers of amino acids and perform a wide range of functions in cells.

Amino Acids: Building blocks of proteins, each with a central carbon, amino group, carboxyl group, and unique side chain (R group).
Peptide Bonds: Covalent bonds that link amino acids together in a polypeptide chain.
Protein Structure: Proteins have four levels of structure: primary (sequence), secondary (folding patterns like alpha helices and beta sheets), tertiary (3D shape), and quaternary (multiple polypeptides).
Denaturation: Loss of protein structure due to changes in temperature, pH, or chemicals.

Example: Enzymes are proteins that catalyze biochemical reactions.

Nucleic acids store and transmit genetic information. The two main types are DNA and RNA.

Nucleotides: Monomers of nucleic acids, each consisting of a sugar, phosphate group, and nitrogenous base.
DNA vs. RNA: DNA contains deoxyribose sugar and is double-stranded; RNA contains ribose sugar and is single-stranded.
Base Pairing: In DNA, adenine pairs with thymine, and cytosine pairs with guanine. In RNA, uracil replaces thymine.
Phosphodiester Bonds: Link nucleotides together in a strand.

Example: DNA stores genetic instructions for protein synthesis.

Type	Sugar	Strands	Bases
DNA	Deoxyribose	Double	A, T, C, G
RNA	Ribose	Single	A, U, C, G

Figures referenced (e.g., 3.2, 3.3, 3.4, etc.) are likely diagrams of molecular structures, reactions, or biological processes. Students should review these in their textbook for visual understanding.
Some content inferred from standard biology curriculum to ensure completeness and clarity.