Biochemistry and Macromolecules in Anatomy & Physiology: Study Guide Ch. 2 4-5

Biochemistry and Water in Anatomy & Physiology

Properties of Water

Water's molecular structure and polarity give it unique properties essential for life and physiological processes.

• High Specific Heat Capacity: Water can absorb and retain heat, helping to stabilize body temperature.

• High Surface Tension: Water molecules are attracted to each other (cohesion), allowing it to form droplets and support small objects.

• Decreases in Density Upon Freezing: Ice is less dense than liquid water, so it floats, which is important for aquatic life.

• High Heat of Vaporization: Water requires significant energy to evaporate, aiding in cooling mechanisms like sweating.

• Solvent Properties: Water dissolves many substances, facilitating chemical reactions in the body.

Example: The high heat capacity of water helps maintain a stable internal environment (homeostasis) in humans.

Cohesion and Cushioning

Hydrogen bonds pull water molecules together, resulting in high cohesion and surface tension. Water's high density allows it to cushion and protect body structures, such as the brain and spinal cord (cerebrospinal fluid).

pH and Hydrogen Ions

The concentration of hydrogen ions ($[H^+]$) in a solution determines its acidity or alkalinity.

• pH Scale: Ranges from 0 (most acidic, highest $[H^+]$) to 14 (most basic, lowest $[H^+]$).

• Acidosis: If blood pH falls below 7.35, the body's systems experience acidosis, which can disrupt cellular functions.

• Buffers: Substances that minimize changes in pH by binding or releasing hydrogen ions.

Equation:

$\text{pH} = -\log_{10}[H^+]$

Macromolecules: Structure and Function

Organic vs. Inorganic Compounds

Organic compounds contain carbon and are typically found in living organisms, while inorganic compounds usually lack carbon.

• Organic Compounds: Carbohydrates, lipids, proteins, nucleic acids

• Inorganic Compounds: Water, salts, acids, bases

Monomers and Polymers

Macromolecules are large molecules formed by joining smaller units called monomers.

• Monomer: A single subunit (e.g., monosaccharide, amino acid, nucleotide, fatty acid)

• Polymer: A chain of monomers (e.g., polysaccharide, protein, nucleic acid)

Types of Macromolecules

Macromolecule	Monomer	Primary Function
Carbohydrates	Monosaccharide	Source of energy
Lipids	Fatty acids, glycerol	Cell membranes, long-term energy storage
Proteins	Amino acids	Enzymatic reactions, structure, muscle building
Nucleic acids	Nucleotide	Store and transmit genetic information

Polymers and Bonds

Polymer	Bond Type
Protein	Peptide bond
Polysaccharide	Glycosidic linkage
Nucleic acid	Phosphodiester bond
Lipid	Ester linkage

Hydrolysis and Dehydration Synthesis

Macromolecules are built and broken down by specific chemical reactions:

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Proteins: Structure and Denaturation

Proteins are composed of amino acids and have four levels of structure: primary, secondary, tertiary, and quaternary.

• Primary Structure: Sequence of amino acids

• Secondary Structure: Alpha helices and beta sheets

• Tertiary Structure: 3D folding of a single polypeptide

• Quaternary Structure: Combination of multiple polypeptide chains (not present in all proteins)

• Denaturation: Loss of protein structure and function due to heat, pH, or chemicals

Amino Acids and Functional Groups

All amino acids contain an amino group (-NH2) and a carboxylic acid group (-COOH).

Lipids: Types and Functions

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

• Phospholipids: Primary lipid in cell membranes, forming the lipid bilayer

• Saturated, Monounsaturated, Polyunsaturated Fats: Differ in the number of double bonds in their fatty acid chains

• Unsaturated Fatty Acid: Contains one or more double covalent bonds

Carbohydrates

Carbohydrates are the body's main source of energy.

• Monosaccharide: Simple sugar, monomer of carbohydrates (e.g., glucose)

• Polysaccharide: Complex carbohydrate (e.g., starch, glycogen)

Nucleic Acids

Nucleic acids (DNA and RNA) store and transmit genetic information.

• Nucleotide: Monomer of nucleic acids

• DNA Bases: Adenine, guanine, cytosine, thymine (uracil replaces thymine in RNA)

• Function: DNA stores genetic code; RNA helps execute genetic instructions

Hydrophobic and Hydrophilic Substances

Substances that do not dissolve easily in water are hydrophobic (e.g., lipids), while those that do are hydrophilic.

Glycoproteins and Glycolipids

These molecules are found on cell membranes and are important for cell recognition and communication.

Buffers and pH Regulation

Buffers help maintain pH balance in the body by preventing large swings in pH when acids or bases are added.

• Major Organ Systems: Respiratory and urinary systems work together to regulate pH.

Acids, Bases, and Salts

• Acid: Releases hydrogen ions ($H^+$) in solution

• Base: Accepts hydrogen ions or releases hydroxide ions ($OH^-$)

• Salt: Ionic compound formed from acid-base reactions

Summary Table: Macromolecules and Their Functions

Macromolecule	Primary Function
Nucleic acids	Store and transmit genetic information
Carbohydrates	Source of energy for the body
Lipids	Form cellular membranes and act as long-term energy storage
Proteins	Catalyze reactions and are building blocks of muscles

Additional info: Some content and explanations have been expanded for clarity and completeness based on standard Anatomy & Physiology curriculum.