Chapter 2 Pt. 2: The Chemical Basis of Life – Page-by-Page Notes
Page 2
- ATP structure and role in energy production cycle
- pH scale and buffers in body fluids
- Distinguish inorganic vs organic compounds
- Functional roles of inorganic compounds
- Structures and functions of carbohydrates, lipids, proteins, nucleic acids
- Structures and functions of high-energy compounds
- Relationship between chemicals and cells
- Need for enzymes in biological reactions
Page 3
- Chemical energy stored in chemical bonds; potential energy in foods (e.g., glucose)
- ATP synthesis from ADP, Pi, and energy from food:
\mathrm{ADP + Pi + energy \rightarrow ATP} - Energy transfer from glucose to high-energy phosphate bonds
Page 4
- ATP components: Adenine, Ribose (adenosine), and three phosphate groups
- High-energy phosphate bonds enable energy storage and transfer
Page 5
- ATP energy cycle: phosphorylation to form ATP; ATP hydrolysis releases energy
- Formation and breakdown:
\mathrm{ADP + Pi + energy \rightarrow ATP} (dehydration synthesis; water produced)
\mathrm{ATP \rightarrow ADP + Pi + energy} (hydrolysis) - AMP can be a starting point for phosphate attachment to form ATP
Page 6
- Anabolism: energy used to build complex molecules
- Catabolism: energy released to power cellular activities
- Continuous recycling of ADP and ATP within cells
Page 7
- Acids & Bases: H+ is a proton; pH reflects H+ concentration
- Normal body pH is tightly regulated: 7.35 \leq \text{pH} \leq 7.45
- pH scale is logarithmic; small changes represent large shifts in H+/OH- concentration
Page 8
- Definitions:
- Acid: donor of H+; pH < 7
- Base: acceptor of H+; pH > 7
- Acids, bases, and salts dissociate in water to form ions; neutralization occurs when H+ and OH- combine
Page 9
- Practical example: stomach acid and antacids (neutralization) disrupts pH balance
- Note: acids release H+, bases release OH-
Page 10
- Buffers maintain blood pH 7.35–7.45 by:
- Neutralizing excess H+ (forming water) or
- Releasing H+ as needed
- Buffers support homeostasis
Page 11
- Inorganic compounds: small, often without carbon and hydrogen (e.g., H2O, CO2, O2)
- Organic compounds: large, with C and H (often with O, N, P, S); typically contain carbon-hydrogen framework
- CO2 is an exception (no H)
- Nutrients vs metabolites
Page 12
- Organic molecules: contain C and H in greatest amounts; may include O, N, P, Fe, S
- Polar = water-soluble
- Include four main groups: Carbohydrates, Lipids, Nucleic Acids, Proteins
Page 13
- Carbohydrates: C, H, O in ~1:2:1; covalent bonds
- Energy source; stored as glycogen in liver
- Types: Monosaccharides, Disaccharides, Polysaccharides
Page 14
- Monosaccharides: simple sugars/building blocks; dissolve readily in water
- Key example: glucose (main energy source); also fructose and galactose
- Covalent bonds in sugars hold them together
Page 15
- Disaccharides: sucrose, maltose, lactose
- Formed by dehydration synthesis; broken down by hydrolysis
Page 16
- Polysaccharides: starches and glycogen
- Multiple monosaccharides linked by covalent bonds
- Glycogen stored in liver; starch stored in plants
Page 17
- Lipids: carbon-to-hydrogen ratio ~1:2; less O; diverse elements
- Classes: fatty acids, fats, steroids, phospholipids
- Generally insoluble in water; important for energy storage and membranes
Page 18
- Fatty acids: long carbon chains with a carboxyl group
- Amphipathic: carboxyl end is water-soluble; tail is nonpolar
- Types: Saturated (no double bonds) and Unsaturated (with double bonds)
- Roles: energy storage, insulation, cushioning, membrane components
Page 19
- Saturated vs. Unsaturated:
- Saturated: straight chains, readily pack with other saturated molecules
- Unsaturated: double bonds create bends; fewer hydrogens around double bond
- Implications for bonding and health (arterial risk with excess saturated fats)
Page 20
- Fats (triglycerides): glycerol + three fatty acids
- Functions: energy storage, insulation, protection
- Excess fats linked to arteriosclerosis
Page 21
- Steroids: four-ring carbon structure
- Examples: Cholesterol, bile salts, Vitamin D
- Roles: membrane structure; precursor to sex hormones; health risks with high cholesterol
Page 22
- Phospholipids: major membrane lipids
- Structure: glycerol + two fatty acids + phosphate group + nonlipid group
- Amphipathic: hydrophilic head; hydrophobic tails
Page 23
- Lipids table (summary):
- Fatty Acids: energy source
- Fats: energy storage, insulation, protection
- Steroids (e.g., Cholesterol): membrane structure; hormones; bile; Vitamin D
- Phospholipids: membrane structure
Page 24
- Protein basics: built from amino acids (20 types)
- Structure: central carbon, hydrogen, amino group, carboxyl group, R group
- Not stored in body; assembled as needed
Page 25
- Dehydration synthesis forms peptide bonds between amino acids
- Example: glycine + alanine → dipeptide
Page 26
- Protein functions (7):
- Support (cell membranes, skin, nails)
- Movement (actin/myosin in muscle)
- Transport (e.g., hemoglobin for O2)
- Buffering (blood pH)
- Metabolic regulation (enzymes)
- Coordination and control (hormones)
- Defense (immune components)
Page 27
- Protein structure: function dictated by amino acid sequence and R groups
- Folding interactions yield fibrous (structural) vs globular (functional) proteins
- Denaturation: changes in temperature, pH, or ionic environment can disrupt structure and function
Page 28
- Primary structure: linear sequence of amino acids
- Secondary structure: alpha helix or beta sheet formed by hydrogen bonds along the chain
Page 29
- Tertiary structure: 3D folding of a single polypeptide; examples include hemoglobin (globular) and collagen (fibrous)
- Quaternary structure: multiple polypeptide subunits form a larger protein complex
Page 30
- Enzymes: essential protein catalysts
- Lower activation energy; reusable; require appropriate temp and pH
Page 31
- Enzyme mechanism: substrates bind at active site to form enzyme-substrate complex
- Binding alters enzyme shape to promote product formation; products released; enzyme ready to catalyze again
Page 32
- Nucleic Acids: store and process genetic information
- Composed of nucleotides: sugar, phosphate, nitrogenous base
- Two classes: DNA and RNA
Page 33
- DNA (Deoxyribonucleic Acid):
- Double-stranded helix; sugar is deoxyribose
- Bases: A, G, C, T
- Base pairing: A with T, G with C
- Stores genetic information for protein synthesis and organism development
Page 34
- RNA (Ribonucleic Acid):
- Single-stranded; sugar is ribose
- Bases: A, G, C, U
- Base pairing: A with U, G with C (uracil replaces thymine)
- Carries out protein synthesis as directed by DNA
Page 35
- DNA vs RNA overview: DNA stores hereditary information; RNA mediates protein synthesis
- RNA structure determined by sequence and intra-molecular interactions; DNA structure determined by complementary base pairing