Chemistry of Life: Water, Functional Groups, and Biomolecules

Study Guide - Smart Notes

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

Chemistry of Life

Water

Water is a fundamental molecule for life, exhibiting unique chemical and physical properties due to its structure and bonding. Understanding these properties is essential for grasping biological processes.

Bonds within Water: Water molecules are held together by polar covalent bonds between hydrogen and oxygen atoms. Between molecules, hydrogen bonds form due to polarity.
Polarity: Water is a polar molecule, meaning it has a partial positive charge on hydrogen and a partial negative charge on oxygen.
Cohesion: Water molecules stick to each other via hydrogen bonds, resulting in surface tension.
Adhesion: Water molecules can stick to other substances, aiding processes like capillary action.
Surface Tension: The cohesive forces at the surface of water create a 'skin' that allows small objects to rest atop it.
Capillary Action: The combination of cohesion and adhesion enables water to move up narrow tubes, important in plant transport.
High Heat Capacity: Water can absorb or release large amounts of heat with little temperature change, stabilizing environments.
Evaporative Cooling: As water evaporates, it removes heat, cooling surfaces (e.g., sweating).
Universal Solvent: Water dissolves many substances due to its polarity, facilitating biochemical reactions.
Example: Water's role in dissolving salts and sugars in the cytoplasm.

Functional Groups

Functional groups are specific clusters of atoms within molecules that confer distinct chemical properties and reactivity. They are essential in organic chemistry and biological molecules.

Name & Identify: Common functional groups include hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), amino (-NH2), sulfhydryl (-SH), phosphate (-PO4), and methyl (-CH3).
Draw: Students should be able to sketch these groups and recognize them in biomolecules.
Example: The carboxyl group in amino acids and fatty acids.

Biomolecules

Monomers and Polymers

Biomolecules are often polymers, made from repeating monomer units. The formation and breakdown of polymers are central to metabolism.

Monomers: Small, repeating units (e.g., glucose, amino acids, nucleotides).
Polymers: Large molecules made from monomers (e.g., starch, proteins, DNA).
Dehydration Synthesis: The process of joining monomers by removing water.
Hydrolysis: Breaking polymers into monomers by adding water.
Role of Carbon: Carbon's ability to form four covalent bonds makes it the backbone of organic molecules.
Organic: Molecules containing carbon, typically associated with living organisms.

Carbohydrates

Carbohydrates are energy-providing biomolecules composed of carbon, hydrogen, and oxygen. They exist as monosaccharides, disaccharides, and polysaccharides.

Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose). Isomers have the same formula but different structures.
Disaccharides: Two monosaccharides joined (e.g., sucrose, lactose, maltose).
Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).
Type of Bond: Glycosidic bonds link monosaccharides.
Functions: Energy storage (starch, glycogen), structural support (cellulose).
Example: Starch in plants, glycogen in animals.

Proteins

Proteins are polymers of amino acids, performing diverse functions in cells. Their structure determines their function.

Amino Acids: Each has a central carbon, amino group, carboxyl group, hydrogen, and variable side chain (R group).
Type of Bond: Peptide bonds link amino acids.
Structure Types:
- Primary: Sequence of amino acids.
- Secondary: Alpha helices and beta sheets formed by hydrogen bonding.
- Tertiary: 3D folding due to side chain interactions.
- Quaternary: Multiple polypeptides joined.
Side Chains: Hydrophobic, hydrophilic, acidic, or basic side chains affect folding.
Denaturation: Loss of structure due to heat, pH, or chemicals, resulting in loss of function.
Functions: Enzymes, structural proteins, transport, signaling.
Example: Hemoglobin, enzymes like amylase.

Lipids

Lipids are hydrophobic molecules used for energy storage, membrane structure, and signaling. They include triglycerides, phospholipids, and steroids.

Triglycerides: Composed of glycerol and three fatty acids.
Phospholipids: Glycerol, two fatty acids, and a phosphate group; major component of cell membranes.
Steroids: Four fused carbon rings (e.g., cholesterol, hormones).
Saturated vs Unsaturated: Saturated fatty acids have no double bonds; unsaturated have one or more.
Type of Bond: Ester bonds link fatty acids to glycerol.
Functions: Energy storage, membrane structure, hormones.
Energy Efficiency: Lipids store more energy per gram than carbohydrates.
Hydrophilic/Hydrophobic: Lipids are generally hydrophobic; phospholipids have hydrophilic heads and hydrophobic tails.
Example: Fats, oils, phospholipids in membranes.

Nucleic Acids

Nucleic acids store and transmit genetic information. They are polymers of nucleotides.

Nucleotide Components: Phosphate group, five-carbon sugar (ribose or deoxyribose), nitrogenous base.
DNA: Double-stranded, stores genetic information.
RNA: Single-stranded, involved in protein synthesis.
ATP: Adenosine triphosphate, energy currency of the cell.
Type of Bond: Phosphodiester bonds link nucleotides.
Functions: Genetic storage (DNA), protein synthesis (RNA), energy transfer (ATP).
Example: DNA in chromosomes, mRNA in translation.

Biomolecules Identification Lab

Laboratory tests are used to identify the presence of specific biomolecules in samples.

Test	Biomolecule Detected	Positive Result
Biuret	Protein	Purple color
Benedict's	Simple sugars	Green-yellow-red color
Sudan Test	Lipids	Layered appearance
Lugol's	Starch	Black color

Example: Using Benedict's test to detect glucose in urine samples.

Additional info: These topics are foundational for understanding cell structure, metabolism, and genetics in biology.