Slide 1-2: Introduction

• Title: "Chemistry of Life – Chapter 2"

• Learning Objectives:

  • Describe the structure of an atom, including protons, neutrons, and electrons.

  • Define and discuss elements, molecules, and compounds, highlighting their roles in biological systems.

  • Compare major types of chemical bonding: ionic, covalent, and hydrogen bonds.

  • Distinguish between organic and inorganic compounds, emphasizing their relevance to living organisms.

  • Discuss water's chemical characteristics, including its role as a solvent and its importance in chemical reactions.

  • Explain the properties of acids, bases, and salts, including their effects on body functions.

  • Explain the concept of pH and its significance in maintaining homeostasis.

  • Describe the structure and function of organic molecules: carbohydrates, lipids, proteins, and nucleic acids.

Slide 3-5: Levels of Chemical Organization

• Atom: Smallest unit of matter that retains properties of an element.

  • Nucleus: Central core containing protons (positively charged particles) and neutrons (neutral particles).

  • Proton: Determines atomic number, contributes to identity of the element.

  • Neutron: Contributes to atomic mass but not charge.

  • Atomic Number: Number of protons in the nucleus, unique to each element.

  • Atomic Mass: Combined number of protons and neutrons.

• Energy Levels:

  • Electrons: Negatively charged particles surrounding the nucleus.

  • Orbitals: Regions around the nucleus where electrons are likely found; each energy level can hold up to a certain number of electrons.

  • Valence Electrons: Electrons in the outermost energy level that determine chemical reactivity.

  • Electron Shells: Energy levels are arranged in shells; the first shell can hold up to 2 electrons, the second up to 8, and so on.

  • Octet Rule: Atoms are most stable when they have eight electrons in their valence shell, leading to chemical bonding.

  • Isotopes: Variants of elements with different numbers of neutrons; some are radioactive and can be used in medical imaging and treatments.

Slide 6: Elements, Molecules, and Compounds

• Element: Pure substance consisting of only one type of atom (e.g., oxygen, carbon).

  • Periodic Table: Organizes elements based on atomic number and similar chemical properties.

  • Essential Elements for Life: Includes carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (CHNOPS), which are crucial for biological molecules.

• Molecule: Group of atoms chemically bonded together (e.g., O₂, H₂O).

  • Diatomic Molecules: Molecules consisting of two atoms of the same element (e.g., N₂, O₂).

• Compound: Substance made of molecules with different elements bonded together (e.g., NaCl).

  • Chemical Formula: Represents the types and numbers of atoms in a compound (e.g., H₂O for water).

  • Structural Formula: Shows the arrangement of atoms within a molecule, providing insight into its properties and reactivity.

Slide 7-8: Chemical Bonding

• Chemical Bonds:

  • Form when atoms interact to achieve a stable outer energy level (octet rule).

  • Atoms may share, donate, or accept electrons to stabilize their outer shells.

  • Types include ionic, covalent, and hydrogen bonds.

  • Chemical Stability: Atoms bond to become more stable, achieving a full valence shell.

  • Bond Energy: The amount of energy required to break a bond; different types of bonds have varying strengths, with covalent bonds generally being stronger than ionic bonds.

Slide 9-10: Ionic Bonds

• Ions: Atoms that have gained or lost electrons.

  • Cations: Positively charged ions (e.g., Na+).

  • Anions: Negatively charged ions (e.g., Cl-).

• Ionic Bonds:

  • Formed between oppositely charged ions through the transfer of electrons.

  • Electrolytes: Ionic compounds that dissociate in water, producing ions that conduct electrical currents (e.g., salts like NaCl).

  • Properties of Ionic Compounds: Typically form crystalline structures, have high melting points, and conduct electricity when dissolved in water.

  • Role in Biological Systems: Electrolytes like sodium, potassium, and calcium are essential for nerve impulse transmission and muscle contraction.

Slide 11: Covalent Bonds

• Covalent Bonds:

  • Atoms share electrons to complete their outer energy levels.

  • Nonpolar Covalent Bonds: Electrons shared equally (e.g., O₂).

  • Polar Covalent Bonds: Unequal sharing of electrons, leading to partial charges (e.g., H₂O).

  • Form the backbone of organic molecules (e.g., proteins, lipids).

  • Do not easily dissociate in water, making them strong and stable bonds.

  • Single, Double, and Triple Bonds: Covalent bonds can involve the sharing of one, two, or three pairs of electrons, respectively (e.g., H-H, O=O, N≡N).

  • Role in Metabolism: Covalent bonds store energy that can be released during metabolic processes.

Slide 12-13: Hydrogen Bonds

• Hydrogen Bonds:

  • Weak bonds that form between slightly positive hydrogen atoms and slightly negative atoms of neighboring molecules.

  • Important in maintaining the structure of proteins and DNA.

  • Provide cohesion in water molecules, leading to unique properties like surface tension and capillary action.

  • Role in Biological Molecules: Stabilize the alpha-helix and beta-pleated sheet structures in proteins; help maintain the double helix structure of DNA.

  • Temperature Regulation: Hydrogen bonds in water contribute to its high specific heat, allowing organisms to maintain stable internal temperatures.

Slide 14-15: Inorganic Chemistry

• Organic Compounds:

  • Contain carbon-carbon or carbon-hydrogen bonds.

  • Generally larger, more complex molecules (e.g., glucose, proteins).

  • Functional Groups: Specific groups of atoms within molecules that determine the chemical properties of organic compounds (e.g., hydroxyl, carboxyl, amino).

  • Macromolecules: Large organic molecules, including carbohydrates, lipids, proteins, and nucleic acids, essential for life processes.

• Inorganic Compounds:

  • Do not contain C-C or C-H bonds (e.g., water, salts).

  • Smaller and less complex than organic molecules.

  • Include substances like minerals and gases (e.g., oxygen, carbon dioxide).

  • Role in the Body: Inorganic compounds are vital for processes such as oxygen transport, acid-base balance, and electrolyte function.

Slide 16-17: Water

• Water:

  • Inorganic, essential to life.

  • Acts as a solvent, dissolving solutes to form aqueous solutions.

  • Involved in chemical reactions like dehydration synthesis (forming bonds by removing water) and hydrolysis (breaking bonds by adding water).

  • Crucial for temperature regulation and transport of nutrients and wastes.

  • High Heat Capacity: Water can absorb large amounts of heat without a significant change in temperature, helping maintain homeostasis.

  • High Heat of Vaporization: Requires significant energy to change from liquid to gas, allowing for effective cooling through sweating.

  • Polarity and Hydrogen Bonding: Water's polarity allows it to dissolve many substances, and hydrogen bonding contributes to its unique properties.

  • Cohesion and Adhesion: Water molecules stick to each other (cohesion) and to other surfaces (adhesion), facilitating capillary action in plants and blood vessels.

Slide 18: Acids, Bases, and Salts

• Acid: Increases H+ concentration in a solution (e.g., HCl).

  • Strong vs. Weak Acids: Strong acids completely dissociate in water (e.g., HCl), while weak acids partially dissociate (e.g., acetic acid).

• Base: Decreases H+ concentration, often increasing OH- (e.g., NaOH).

  • Alkaline Solutions: Bases create solutions with a pH greater than 7.

• Salts: Formed by the neutralization reaction between acids and bases.

  • Electrolytes are formed when salts dissociate in water, crucial for nerve impulse transmission and muscle contraction.

  • Buffer Systems: Help maintain acid-base balance in the body by neutralizing excess acids or bases.

  • Biological Importance: Maintaining proper pH is essential for enzyme function and overall cellular health.

Slide 19-20: pH

• pH Scale:

  • Ranges from 0 to 14; measures H+ concentration.

  • 7 is neutral; <7 is acidic; >7 is basic.

  • Logarithmic Scale: Each pH unit represents a tenfold difference in H+ concentration.

• Buffers: Chemical systems that resist changes in pH by absorbing or releasing H+ ions (e.g., bicarbonate buffer system in blood).

  • Importance in Physiology: Buffers maintain the pH of body fluids within a narrow range, essential for enzyme activity and metabolic processes.

  • Examples in the Body: The carbonic acid-bicarbonate buffer system helps regulate blood pH, while phosphate buffers are important in intracellular fluids.

Slide 21-23: Organic Chemistry - Carbohydrates

• Carbohydrates:

  • Composed of carbon (C), hydrogen (H), and oxygen (O).

  • Monosaccharides: Simple sugars; basic units (e.g., glucose).

    • Glucose: Primary source of energy for cells, involved in cellular respiration.

    • Fructose: Found in fruits; used as a source of energy.

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

    • Sucrose: Common table sugar, composed of glucose and fructose.

    • Lactose: Sugar found in milk, composed of glucose and galactose.

  • Polysaccharides: Many monosaccharides; complex (e.g., glycogen, starch).

    • Glycogen: Storage form of glucose in animals, primarily found in liver and muscle cells.

    • Starch: Storage form of glucose in plants.

    • Cellulose: Structural component of plant cell walls; not digestible by humans but important for dietary fiber.

  • Functions include energy storage and providing structural support (e.g., cellulose in plant cell walls).

Slide 24-26: Lipids

• Triglycerides:

  • Formed by glycerol and three fatty acids.

  • Store energy for later use.

  • Saturated vs. Unsaturated Fatty Acids:

    • Saturated: No double bonds between carbon atoms; solid at room temperature (e.g., butter).

    • Unsaturated: One or more double bonds; liquid at room temperature (e.g., olive oil).

    • Trans Fats: Unsaturated fats that have been hydrogenated; associated with increased health risks.

• Phospholipids:

  • Similar to triglycerides but contain phosphorus.

  • Have a hydrophilic head (water-attracting) and hydrophobic tails (water-repelling).

  • Form the bilayer of cell membranes, crucial for membrane structure.

  • Amphipathic Nature: The dual nature of phospholipids allows them to form selective barriers in biological membranes.

  • Role in Cell Signaling: Phospholipids are involved in cell signaling pathways, contributing to the regulation of cellular activities.

• Cholesterol:

  • Multiple-ring structure.

  • Helps stabilize cell membranes and is a precursor for steroid hormones (e.g., estrogen, testosterone).

  • Role in Bile Production: Cholesterol is used by the liver to produce bile, which aids in the digestion of fats.

  • Lipoproteins: Cholesterol is transported in the blood by lipoproteins (e.g., LDL - low-density lipoprotein, and HDL - high-density lipoprotein), which play a role in cardiovascular health.

Slide 27-29: Proteins

• Structural Proteins:

  • Composed of amino acids linked by peptide bonds (chemical bonds that link amino acids together to form proteins)

  • Collagen: Provides structural support in connective tissues; most abundant protein in the body.

  • Keratin: Forms tough, protective layers in skin, hair, and nails.

• Functional Proteins:

  • Includes enzymes, hormones, and receptors.

  • Enzymes: Biological catalysts that speed up chemical reactions (e.g., lock-and-key model).

    • Active Site: Region on the enzyme where substrates bind and reactions occur.

    • Specificity: Enzymes are specific to substrates due to the shape of their active site.

    • Cofactors and Coenzymes: Non-protein molecules that assist enzymes in catalyzing reactions (e.g., vitamins as coenzymes).

  • Denaturation: Loss of protein structure and function due to extreme pH, temperature, or chemical exposure.

  • Hormones: Proteins that act as chemical messengers (e.g., insulin regulates blood glucose levels).

  • Antibodies: Specialized proteins produced by the immune system to identify and neutralize foreign substances.

Slide 30-33: Nucleic Acids

• Nucleotides: Building blocks of nucleic acids.

  • Each composed of a phosphate unit, a sugar (ribose or deoxyribose), and a nitrogen base.

  • Nitrogen Bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G), and Uracil (U) (in RNA).

• DNA (Deoxyribonucleic Acid):

  • Contains genetic information; guides protein synthesis.

  • Double helix structure with bases A, T, C, G.

  • Base Pairing: A pairs with T, and C pairs with G.

  • Replication: Process by which DNA makes a copy of itself during cell division.

  • Genetic Code: Sequence of nucleotides determines the sequence of amino acids in proteins, which ultimately determines the structure and function of the protein.

• RNA (Ribonucleic Acid):

  • Acts as a temporary copy of DNA for protein synthesis.

  • Single-stranded, with bases A, U, C, G.

  • Types of RNA:

    • mRNA (Messenger RNA): Carries genetic information from DNA to ribosomes.

    • tRNA (Transfer RNA): Brings amino acids to ribosomes during protein synthesis.

    • rRNA (Ribosomal RNA): Component of ribosomes, where protein synthesis occurs.

  • Transcription and Translation: RNA is synthesized from DNA (transcription), and proteins are synthesized from RNA (translation).

Slide 34-35: ATP - Adenosine Triphosphate

• ATP:

  • Energy currency of the cell.

  • Provides energy for cellular activities like muscle contraction, active transport, and synthesis reactions.

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

  • ATP Cycle: ATP is converted to ADP (adenosine diphosphate) when energy is released, and then regenerated through cellular respiration.

  • Role in Metabolism: ATP provides the energy needed for anabolic (building) and catabolic (breaking down) processes in the body.

  • Mitochondria: Organelles known as the "powerhouses" of the cell where most ATP is produced through aerobic respiration.