Saladin_AP_10e_Chap02_PPT

Introduction to Biochemistry

• Biochemistry: Study of molecules composing living organisms, including carbohydrates, fats, proteins, and nucleic acids.

• Importance: Essential for understanding cellular structures, basic physiology, nutrition, and health.

Atoms, Ions, and Molecules

Expected Learning Outcomes

• Identify elements from their symbols.

• Distinguish between elements and compounds.

• State functions of minerals in the body.

• Explain radioactivity and hazards of ionizing radiation.

• Distinguish between ions, electrolytes, and free radicals.

• Define types of chemical bonds.

Chemical Elements

• Definition: Simplest matter form with unique chemical properties, identified by atomic number (number of protons).

• Periodic Table: Arranges 91 elements by atomic number; 24 are relevant for humans, 6 (O, C, H, N, Ca, P) constitute 98.5% of body weight.

• Trace Elements: Present in minute amounts, vital roles in body functions (e.g., iron in oxygen transport).

Atomic Structure

• Atom: Basic unit of matter.

• Models: Niels Bohr's planetary model vs. more accurate quantum mechanical models.

• Components:

  • Nucleus: Contains protons (+) and neutrons (no charge).

  • Electrons: Negatively charged particles in energy levels around the nucleus.

• Valence Electrons: Determine chemical bonding properties.

Isotopes and Radioactivity

• Isotopes: Variants of an element differing in neutron number. Examples: Hydrogen isotopes (1H, 2H, 3H).

• Radioisotopes: Unstable isotopes that decay, emitting radiation.

• Ionizing Radiation: Can destroy molecules, harmful to health, can cause cancer.

• Radiation Dosage: Measured in sieverts (Sv). Fatal level: 5 Sv; acceptable yearly exposure: 50 mSv.

Ions, Electrolytes, and Free Radicals

Definition of Ions

• Ions: Charged particles (anions have gained electrons; cations have lost electrons).

• Ionization: Transfer of electrons between atoms.

Electrolytes

• Characteristics: Substances that dissociate in water, conducting electric currents.

• Functions: Chemical reactivity, osmotic effects, electrical excitability.

Free Radicals

• Unstable, reactive species with unpaired electrons, contributing to health issues (e.g., cancer, aging).

• Antioxidants: Neutralize free radicals (e.g., vitamins C, E).

Molecules and Chemical Bonds

Definitions

• Molecule: Composed of two or more atoms (e.g., compounds are specific types of molecules).

• Chemical Bond Types:

  • Ionic Bonds: Formed by attraction between cations and anions.

  • Covalent Bonds: Formed by sharing electrons; can be single or double bonds.

Hydrogen Bonds

• Weak attractions that stabilize the structure of large molecules (e.g., DNA, proteins).

Van der Waals Forces

• Brief attractions between neutral atoms, play roles in molecular physiologies, such as protein folding.

Water and Mixtures

Properties of Water

• Solvency: Water is termed the universal solvent due to its ability to dissolve many substances.

• Cohesion and Adhesion: Crucial for transporting water in plants and reducing friction in bodily organs.

• Chemical reactivity and Thermal stability: Water participates in metabolic reactions and stabilizes internal temperatures.

Mixture Types

• Solutions: Solute particles less than 1 nm, will not separate (e.g., saltwater).

• Colloids: Mixed substances that can change states (e.g., proteins in water).

• Suspensions: Can separate upon standing (e.g., blood).

Acids, Bases, and pH

Definitions

• Acid: Proton donor (releases H+ in water).

• Base: Proton acceptor (binds H+ in water).

• pH Scale: Measures acidity, with 7 being neutral; importance in physiological functions (buffers stabilize pH).

Other Measures of Concentration

• Weight per Volume: Amount of solute in a given volume of solution (e.g., IV saline).

• Molarity: Number of moles of solute per liter of solution.

• Milliequivalents: Measures of electrolyte concentration, important for physiological functions.

Energy and Chemical Reactions

Energy Basics

• Energy: Capacity to do work; divides into potential and kinetic forms.

• Chemical Reactions: Bonds formed or broken during processes; classified into decomposition, synthesis, and exchange reactions.

Metabolism

• Catabolism: Energy-releasing decomposition reactions.

• Anabolism: Energy-storing synthesis reactions.

Organic Compounds

Types of Organic Molecules

• Carbohydrates: Provide quick energy.

• Lipids: High energy storage molecules involved in membrane structures and signaling.

• Proteins: Polymers of amino acids, essential for numerous biological functions, including catalysis and transport.

• Nucleic Acids: DNA and RNA, carrying genetic information.

Enzyme Functions

• Enzymes catalyze reactions by lowering activation energy; specificity due to active sites.

• Factors affecting enzyme activity include temperature and pH.

ATP and Nucleotides

ATP Structure and Function

• ATP is the main energy transfer molecule in the body, produced primarily from the breakdown of glucose.

• Energy is stored in high-energy phosphate bonds and released upon hydrolysis.

Conclusion

• Understanding biochemistry is vital in contexts of anatomy, physiology, and health.