Biol131 Lecture 2 Chemistry

Chapter Overview

  • Chemistry underlies physiological reactions in the body, such as movement, digestion, heart function, and nervous system activity.

  • Chemistry can be divided into basic chemistry and biochemistry.

Energy

  • Definition: Energy is the capacity to do work or move matter.

  • Characteristics:

    • Energy has no mass and does not occupy space.

    • More work done means more energy consumed.

Forms of Energy

  • Kinetic Energy: Energy of motion; e.g., moving objects.

  • Potential Energy: Stored or inactive energy that can be converted to kinetic energy.

Types of Energy

  • Chemical Energy: Stored in molecules; released during reactions.

  • Thermal Energy: Energy from moving particles (heat).

  • Mechanical Energy: Energy of objects in motion.

  • Electrical Energy: Moves through wires; electricity.

  • Magnetic Energy: Push/pull forces.

  • Sound Energy: Energy we can hear.

  • Light Energy: Detectable by our eyes.

  • Elastic Energy: Stored in stretched objects.

  • Nuclear Energy: Stored in atoms' nuclei.

  • Gravitational Energy: Related to an object's height.

Atoms and Elements

  • Definition: All matter is composed of elements.

  • Elements: Cannot be broken down into simpler substances by chemical means.

    • Key Elements in the Body: 96% consists of Carbon (C), Oxygen (O), Hydrogen (H), and Nitrogen (N).

    • Other trace elements in small quantities.

Atomic Structure

  • All elements are made of atoms, the smallest units maintaining properties of an element.

  • Atomic Symbols: One- or two-letter designations of elements (e.g., O for oxygen, C for carbon).

Periodic Table

  • Lists all known elements and their properties.

Common Elements in the Human Body

  • Major Elements (96.1%):

    • Oxygen (O): 65%, essential for cellular energy production.

    • Carbon (C): 18.5%, a component of organic molecules.

    • Hydrogen (H): 9.5%, influences body fluid pH.

    • Nitrogen (N): 3.2%, part of proteins and nucleic acids.

  • Lesser Elements (3.9%): Calcium, Phosphorus, Potassium, Sulfur, Sodium, Chlorine, Magnesium, Iodine, Iron.

  • Trace Elements (<0.01%): Essential in minute amounts; include elements like Zinc, Copper, and others.

Structure of Atoms

  • Subatomic Particles: Protons (+), Neutrons (0), Electrons (-).

  • Atom Structure: Protons and neutrons are in the nucleus, while electrons orbit around.

  • Key Identification Details: Atomic number (number of protons), mass number (protons + neutrons).

Isotopes and Radioactivity

  • Isotopes: Variants of an element with the same number of protons but different neutrons.

  • Radioisotopes: Isotopes that decay to stable forms; used in medical diagnostics but can damage tissue.

Chemical Bonds and Reactions

  • **Key Types of Bonds:

    • Ionic Bonds:** Formed by transfer of electrons between atoms, resulting in charged ions.

    • Covalent Bonds: Result from sharing of electrons; can be nonpolar or polar.

    • Hydrogen Bonds: Weak attractions between molecules, significant in structures like water.

  • Chemical Reactions: Involve the forming and breaking of chemical bonds; represented by chemical equations showing reactants and products.

Inorganic and Organic Compounds

Inorganic Compounds

  • Most important: Water (60–80% cell volume) with unique properties: high heat capacity, solvent, reactivity, and cushioning effect.

  • Salts: Ionic compounds that dissociate into cations and anions in water, crucial for different biological functions.

Organic Compounds

  • Contain carbon; include carbohydrates, lipids, proteins, and nucleic acids.

  • Often polymers made of monomers, through synthesis reactions like dehydration.

Carbohydrates

  • Include sugars and starches, composed of C, H, O in 2:1 ratio.

  • Three classes: Monosaccharides, Disaccharides, Polysaccharides.

Lipids

  • Contain C, H, O, less than carbohydrates. Types include triglycerides, phospholipids, steroids, and eicosanoids.

  • Triglycerides: Energy storage; consist of three fatty acids linked to glycerol.

Proteins

  • Comprise cell mass, involved in various functions (structural, enzymes, transport).

  • Made from 20 types of amino acids joined by peptide bonds, exhibiting four structural levels (primary, secondary, tertiary, quaternary).

  • Enzymes: Biological catalysts that speed up chemical reactions.

Nucleic Acids

  • Largest molecules in the body, made of nucleotides, two types: DNA and RNA.

  • DNA: Double-stranded, contains genetic information; follows specific pairing rules.

  • RNA: Single-stranded, links DNA to protein synthesis using codons.

Energy in Cells

  • ATP (Adenosine Triphosphate): Main energy currency in cells, structure includes adenine, ribose, and three phosphates; hydrolysis of ATP releases energy.

Conclusion

  • Chemistry basics enable understanding of more complex physiological processes and the role of different biomolecules in sustaining life.