Chapter 2: The Molecules of Cells Unit 1: Cell Biology Chapter 2: The Molecules of Cells
Covalent Reactions Atoms SHARE electrons
More Covalent Reactions
Ionic Reactions Atoms GAIN or LOSE electrons Ionic bond= attraction between oppositely charged ions
Hydrogen Bonds Hydrogen bond = covalently bonded hydrogen is positive and attracted to a negatively charged atom Polarity of H20 Hydrogen bonds Cohesive
pH Scale Acidic: pH <7 [H+] > [OH-] Neutral: pH = 7 [H+] = [OH-] Note to self: [H+] = hydrogen ions [OH-]= hyrdoxide ions Acidic: pH <7 [H+] > [OH-] Neutral: pH = 7 [H+] = [OH-] Basic: pH >7 [H+] < [OH-]
Synthesis (dehydration) & Hydrolysis Monomer= simple organic molecule, exists individually Polymer/Macromolecule= many monomers linked together
Examples of Monomers and Polymers carbohydrate monosaccharide protein Amino acids Nucleic acid nucleotides lipids Fatty acids See page 31 in Inquiry into Life text
Carbohydrates (CH2O)n Functions: a) quick & short term energy storage b) structural role in plants, bacteria, insects Types: Monosaccharide= simple sugar, 3-7 carbon atoms ex. Glucose, fructose, galactose Disaccharide= two monosaccharides joined by dehydration ex. Maltose, sucrose, lactose Polysaccharide= long polymers of many glucose subunits ex. Starch, glycogen, cellulose
Synthesis and Degradation of Maltose, a disaccharide
Lipids Functions: energy storage Types: Fats (triglyceride) and Oils Saturated Fatty Acid= no double covalent bonds between carbon atoms (saturated) Unsaturated Fatty Acid= has double bonds between carbon atoms Phospholipids- like fats but has phosphate group instead of third fatty acid Steroids- has a backbone of 4 fused carbon rings (Cholesterol is a type of steroid)
Synthesis and Degradation of a Fat molecule
Structure of a phospholipid and steroid See Figures 2.22 and 2.23 in Inquiry into Life textbook
Proteins Proteins= polymers of amino acid monomers Many functions! Some examples: Keratin- skin and nails Collagen- ligaments, tendons, skin Many hormones Actin and Myosin- allow muscles to contract Hemoglobin- transport oxygen in blood Antibodies in the blood Allow movement through cell membrane Enzymes (speed up chemical reactions)
Representative Amino Acids
Synthesis and Degradation of a dipeptide Amino acids Polypeptides Proteins
Levels of Protein Organization Primary: linear sequence of amino acids joined by a peptide bond Secondary: polypeptides take on a certain orientation in space (alpha helix or pleated sheet) due to hydrogen bonding between peptides Tertiary: final 3D shape maintained by various bonding (covalent, ionic and hydrogen) Quaternary: only in some protein, due to polypeptide arrangements
Levels of Protein Organization
Nucleic Acids Two Types: DNA RNA Sugar Deoxyribose Ribose Bases A,G,T,C A,G,U,C Strands Double Single Helix Yes No Functions Genetic material that specifies protein synthesis mRNA, rRNA, or tRNA Function in protein synthesis
Overview of DNA structure
ATP (Adenosine Triphosphate) Energy carrier in cells High energy molecule because last two phosphate bonds are unstable and easily broken