General Biology Exam 1 Study Guide: Macromolecules, Cell Structure, and Biochemical Foundations

Macromolecules

Types and Properties of Macromolecules

Macromolecules are large, complex molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids. They are typically polymers, formed by joining smaller units called monomers.

• Types of Macromolecules: Carbohydrates, lipids, proteins, nucleic acids

• Monomers vs. Polymers: Monomers are the building blocks; polymers are chains of monomers.

• Functional Groups: Key chemical groups include hydroxyl, carbonyl, carboxyl, amino.

• Example: Glucose contains hydroxyl groups; amino acids contain amino and carboxyl groups.

• Additional info: Functional groups determine chemical reactivity and interactions.

Carbohydrates

Structure and Function

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as energy sources and structural components.

• Structural Types: Monosaccharides (simple sugars), disaccharides, polysaccharides

• Distinguishing Carbohydrates: Based on number of sugar units and functional groups

• Storage Forms: Starch (plants), glycogen (animals)

• Hydrolysis: Breaking down polysaccharides into monosaccharides via water addition

• Common Carbohydrates: Glucose, fructose, sucrose, lactose, starch, glycogen, cellulose

• Structure-Function Relationship: Polysaccharide branching affects energy storage and release

• Carbon and Hydrogen Atoms: Ratio is typically 1:2:1 (C:H:O)

• Example: Cellulose provides structural support in plant cell walls.

Lipids

Types and Biological Roles

Lipids are hydrophobic molecules, including fats, phospholipids, and steroids. They function in energy storage, membrane structure, and signaling.

• Types: Fats (triglycerides), phospholipids, steroids

• Fatty Acids: Saturated (no double bonds), unsaturated (one or more double bonds), Omega-3/6

• Phospholipids: Composed of glycerol, 2 fatty acids, and a phosphate group

• Hydrophobic/Hydrophilic: Phospholipids have hydrophilic heads and hydrophobic tails

• Example: Cholesterol is a steroid that stabilizes cell membranes.

• Additional info: Lipids are not true polymers; they aggregate via hydrophobic interactions.

Proteins

Structure and Function

Proteins are polymers of amino acids, performing diverse functions such as catalysis, transport, and structural support.

• Functions: Enzymes, transport, signaling, structural support

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

• Hydrophobic/Hydrophilic Regions: Affect folding and membrane insertion

• Amino Acid Composition: Amino group, carboxyl group, R group (side chain)

• Example: Hemoglobin transports oxygen in blood.

Genetics and Nucleic Acids

DNA, RNA, and Nucleotide Structure

Nucleic acids store and transmit genetic information. DNA and RNA are polymers of nucleotides, each consisting of a sugar, phosphate, and nitrogenous base.

• DNA vs. RNA: DNA uses bases A, T, C, G; RNA uses A, U, C, G

• Complementary Sequences: DNA strands pair via hydrogen bonds (A-T, C-G)

• Nucleotide Structure: Phosphate group, pentose sugar, nitrogenous base

• Functional Differences: DNA stores genetic info; RNA functions in protein synthesis (mRNA, tRNA, rRNA)

• Example: mRNA carries genetic code from DNA to ribosomes.

Biochemical Reactions

Hydrolysis and Dehydration Synthesis

Biochemical reactions build and break down macromolecules. Dehydration synthesis forms bonds by removing water; hydrolysis breaks bonds by adding water.

• Dehydration Synthesis: Joins monomers, forms covalent bonds, releases water

• Hydrolysis: Breaks covalent bonds, consumes water

• Example: Formation of peptide bonds in proteins via dehydration synthesis

• Base Pairing: Hydrogen bonds between C-G and A-T in DNA

• Additional info: Enzymes catalyze these reactions, increasing efficiency.

Cell Structure

Prokaryotic vs. Eukaryotic Cells

Cells are the basic units of life, classified as prokaryotic (no nucleus) or eukaryotic (nucleus and organelles).

• Key Differences: Eukaryotes have membrane-bound organelles; prokaryotes do not

• Organization: Eukaryotic cells are typically larger and more complex

• Example: Bacteria are prokaryotes; plants and animals are eukaryotes

Cell Membranes and Organelles

Cell membranes are composed of phospholipid bilayers, providing selective permeability. Organelles perform specialized functions.

• Phospholipid Bilayer: Hydrophilic heads face outward; hydrophobic tails face inward

• Organelles: Rough ER, smooth ER, Golgi apparatus, lysosomes, vesicles

• Cytoskeleton: Provides structural support and facilitates movement

• Ribosomes: Synthesize proteins; may be free or bound to ER

• Example: Mitochondria generate ATP via cellular respiration

Membrane Structure and Protein Insertion

Membrane proteins are embedded in the phospholipid bilayer, with hydrophobic regions interacting with lipid tails and hydrophilic regions exposed to aqueous environments.

• Hydrophobic/Hydrophilic Regions: Determine protein orientation and function

• Phospholipid Arrangement: Fatty acid tails inside, phosphate heads outside

• Example: Channel proteins facilitate transport across membranes

Table: Comparison of Macromolecules

Macromolecule	Monomer	Function	Example
Carbohydrate	Monosaccharide	Energy storage, structure	Starch, cellulose
Lipid	Fatty acid, glycerol	Energy storage, membranes	Triglyceride, phospholipid
Protein	Amino acid	Catalysis, transport, structure	Enzyme, hemoglobin
Nucleic Acid	Nucleotide	Genetic information	DNA, RNA

Key Equations

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

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

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