1.1_Chemistry_in_Living_Systems_

Unit 1: Biochemistry

• Introduction to Biochemistry

  • Study of the properties of biological molecules and the chemical processes that occur in living organisms.

Learning Goals

• By the end of this lesson, able to:

  • Explain the difference between intramolecular and intermolecular interactions.

  • Describe electronegativity.

  • Differentiate between hydrophilic and hydrophobic interactions.

  • Identify functional groups in biological molecules.

1.1 – Chemistry in Living Systems

• Biochemistry

  • The branch of science focusing on biological molecules and the chemistry of living systems.

Atoms, Elements, and Compounds

• Composition of Matter

  • All matter is composed of elements, which cannot be broken down further.

  • Periodic Table of Elements:

    • Groups (1-18) include various classifications of elements like alkali metals, alkaline earth metals, transition metals, noble gases, and others.

Essential Elements in the Human Body

• Four Essential Elements

  • Hydrogen (63%)

  • Oxygen (26%)

  • Carbon (9%)

  • Nitrogen (1%)

• Other Essential Elements:

  • Mineral Elements (0.07%): Ca, P, K, S, Na, Cl, Mg

  • Trace Elements (<0.01%): Fe, I, Cu, Zn, Mn, Co, Cr, Se, Mo, F, Sn, Si

The Atom

• Definition of an Atom

  • Smallest particle of an element retaining its properties.

  • Determining Factors:

    • Atomic Number = Number of Protons = Number of Electrons

    • Mass Number = Number of Protons + Neutrons

Isotopes

• Definition

  • Atoms of the same element with the same number of protons but different numbers of neutrons.

  • Radioisotope

    • Unstable isotopes that undergo nuclear decay by emitting radiation.

Applications of Radioisotopes

• Tracers in Medicine

  • Used for diagnosing diseases (e.g., cancer).

  • Radioactive Dating

  • C-14 to N-14 decay for fossil dating.

Chemical Bonding

• Valence Electrons

  • Outermost electrons can interact to form compounds.

• Types of Chemical Bonds:

  • Intramolecular forces confine within molecules.

Ionic and Covalent Bonding

• Ionic Bonding

  • Involves transfer of electrons between metal and non-metal.

• Covalent Bonding

  • Involves sharing of valence electrons among non-metals.

Understanding Biological Molecule Properties

• Importance of understanding molecular properties to comprehend biological functions (e.g., DNA, proteins, etc.).

Interactions Within Molecules

• Polarity

  • Not all covalent bonds behave similarly; electronegativity varies across elements.

• Electronegativity

  • Measure of an atom’s ability to attract shared electron pairs.

  • Dominates bond types and molecular behaviors.

Bond Type Based on Electronegativity Difference (∆EN)

• Types of Bonds:

  • ∆EN < 0.4 : Non-polar covalent

  • ∆EN 0.4 - 1.7 : Polar covalent

  • ∆EN > 1.7 : Ionic

Examples of Bonds

• Water Molecule (H2O)

  • Oxygen has higher electronegativity than hydrogen, resulting in a polar covalent bond.

Hydrophilic vs. Hydrophobic Interactions

• Hydrophilic Molecules

  • Polar molecules that interact positively with water.

• Hydrophobic Molecules

  • Non-polar molecules that repel water (e.g., fats).

Importance of Water in Biology

• Composes over 65% of body mass.

• Solvent for reactions in the body, indicating compounds must dissolve in water for cellular use.

Ions in Biological Systems

• Role of Ions

  • H+ in cellular respiration, Na+ and K+ in transport, Ca+ in nerve transmission.

Functional Groups

• Definition & Importance

  • Reactive clusters in biological molecules affecting physical and chemical properties.

Representing Molecules

• Molecular Formula

  • Shows number of each atom.

• Structural Formula

  • Depicts bonding arrangement.

3D Molecular Models

• Influence of 3D shape on behavior and function

  • Representations: Ball & Stick Model, Space-Filling Model.