Core Concepts in Biochemistry for Anatomy & Physiology

Biochemistry in Anatomy & Physiology

Inorganic vs. Organic Compounds

Biochemistry distinguishes between inorganic and organic compounds, each with unique chemical and physical properties relevant to living organisms.

• Inorganic Compounds: Typically lack carbon-hydrogen bonds; examples include water, acids, bases, and salts.

• Organic Compounds: Contain carbon atoms bonded to hydrogen; examples include carbohydrates, lipids, proteins, and nucleic acids.

• Importance of Carbon: Carbon's ability to form four covalent bonds makes it essential for complex organic molecules.

• Example: Glucose (C6H12O6) is an organic compound vital for cellular energy.

Biologically Important Inorganic Compounds

Inorganic compounds play critical roles in physiological processes.

• Water: Universal solvent, temperature regulation, transport medium.

• Acids and Bases: Regulate pH; acids release H+, bases accept H+.

• Salts: Ionic compounds that dissociate in water, important for nerve and muscle function.

• Buffers: Maintain pH stability in biological systems.

• Example: The bicarbonate buffer system helps maintain blood pH.

pH Scale and Physiological Activity

The pH scale measures hydrogen ion concentration, influencing enzyme activity and cellular function.

• pH Scale: Ranges from 0 (acidic) to 14 (basic); 7 is neutral.

• Blood pH: Normal range is 7.35–7.45; deviations can disrupt physiological processes.

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

• Example: Acidosis occurs when blood pH drops below 7.35.

Carbohydrates: Structure and Function

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

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose).

• Polysaccharides: Long chains (e.g., starch, glycogen, cellulose).

• Function: Provide energy, store energy, and form structural components.

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

Lipids: Structure and Physiological Roles

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

• Triglycerides: Three fatty acids bonded to glycerol; main energy storage form.

• Phospholipids: Major component of cell membranes.

• Steroids: Include cholesterol and hormones.

• Example: Phospholipids form the bilayer of cell membranes.

Saturated vs. Unsaturated Fatty Acids

Fatty acids differ in the presence of double bonds, affecting their physical properties and health implications.

• Saturated Fatty Acids: No double bonds; solid at room temperature.

• Unsaturated Fatty Acids: One or more double bonds; liquid at room temperature.

• Trans Fats: Unsaturated fats with trans double bonds; associated with health risks.

• Example: Olive oil contains unsaturated fatty acids; butter contains saturated fatty acids.

Proteins: Structure and Function

Proteins are polymers of amino acids, performing diverse roles in the body.

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Alpha helices and beta sheets formed by hydrogen bonding.

• Tertiary Structure: Three-dimensional folding due to side chain interactions.

• Quaternary Structure: Multiple polypeptide chains assembled together.

• Denaturation: Loss of structure and function due to environmental changes.

• Example: Hemoglobin is a quaternary protein that transports oxygen.

Enzymes and Biological Catalysis

Enzymes are proteins that accelerate biochemical reactions, crucial for metabolism.

• Active Site: Region where substrate binds and reaction occurs.

• Specificity: Each enzyme catalyzes a specific reaction.

• Example: Amylase breaks down starch into sugars in the mouth.

Nucleic Acids: DNA and RNA

Nucleic acids store and transmit genetic information.

• DNA (Deoxyribonucleic Acid): Double helix structure; stores genetic code.

• RNA (Ribonucleic Acid): Single-stranded; involved in protein synthesis.

• Structure: Composed of nucleotides (sugar, phosphate, nitrogenous base).

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

ATP and Physiological Importance

Adenosine triphosphate (ATP) is the primary energy carrier in cells.

• Structure: Adenine base, ribose sugar, three phosphate groups.

• Function: Provides energy for cellular processes.

• Equation: $\text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{Energy}$

• Example: Muscle contraction uses ATP for energy.

Dehydration Synthesis and Hydrolysis

These chemical reactions are fundamental for building and breaking down macromolecules.

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

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

Summary Table: Major Biomolecules

Biomolecule	Monomer	Main Function	Example
Carbohydrates	Monosaccharide	Energy, structure	Glucose, starch
Lipids	Fatty acid, glycerol	Energy storage, membranes	Triglyceride, phospholipid
Proteins	Amino acid	Catalysis, structure, transport	Enzyme, hemoglobin
Nucleic Acids	Nucleotide	Genetic information	DNA, RNA