BIOLOGY 2e SIMPLIFIED AND WELL EXPLAINED SUMMARY FOR EXAM REVISION

Amino Acid Structure Tetrahedral alpha-carbon connected to an amino group, a carboxyl group and a variable R group, which determines the AA's properties Primary Protein Structure Consists of amino acids linked by peptide bonds forming the amino acid sequence Secondary Protein Structure Alpha-helices and Beta-sheets formed through hydrogen-bonding interactions between the atoms in the backbone of the molecule Tertiary Protein Structure Most stable; places polar Amino Acid's on the exterior and nonpolar Amino Acid's on the interior, optimizing interactions between side chains inside the protein Functions of Proteins in the Body Enzymes, structural roles, hormones, receptors, channels, antibodies, transporters, etc. Monosaccharide Carbohydrate monomer: CnH2nOn (i.e. glucose, fructose, galactose, ribose and deoxyribose) Disaccharide Two monosaccharides joined by glycosidic linkages (i.e. maltose, sucrose, and lactose) Can mammals digest glycosidic linkages in disaccharides? Yes, but generally only alpha linkages and not beta linkages Polysaccharides Many monosaccharides linked together (i.e. glycogen [mammals], starch [plants], and cellulose [wood and cotton]); storage units for glucose for energy Lipid Forms Triglycerides, phospholipids, cholesteral and steroids, and terpenes Linear Lipids Triglycerides and phospholipids Ring Structure Lipids Cholesterol and Steroids Triglyceride Structure & Function 3 fatty acids esterified to a glycerol molecule; Energy Storage Phospholipid Structure & Function Derived from diacylglycerol phosphate or DG-P; Form Membranes Cholesterol Function Precursor to the steroid hormones What are the building blocks of nucleic acids [DNA & RNA]? Nucleotides Nucleotide Structure Pentose sugar, purine or pyrimidine base, and 2-3 phosphate units Saturated Fatty Acid Structure No carbon-carbon double bonds, so every carbon is saturated with hydrogen via covalent bonds Unsaturated Fatty Acid Structure One or more double bonds in the tail; almost always Z or cis Lipase Enzymes that hydrolyze fats Why are fats more efficient energy storage than carbohydrates? 1. Packing: hypdrophobicity allows fats to pack together more closely 2. Energy Content: Store much more energy Lipid Bilayer Hydrophobic interactions drive formation and is stabilized by Van der Waals forces between long tails Would a saturated or an unsaturated fatty acid residue have more Van der Wals interactions with neighboring alkyl chains in a bilayer membrane? Saturated fatty acids; unsaturated tend to increase membrane fluidity and the bent shape doesn't fit in as well and has less contact with neighboring groups to form Van der Waals interactions Steroid Structure All have the basic tetracyclic ring system based on the structure of cholesterol Phosphoric Acid Inorganic acid with the potential to donate 3 protons Pyrophosphate 2 phosphate/orthophosphate bound together by anhydride linkage; P-O-P bond is a high-energy phosphate bond so hydrolysis is extremely favorable Why is so much energy stored in the P-O-P anhydride bonds of Phosphoric Acid? 1. When phosphates are linked together, their negative charges repel each other strongly 2. Orthophosphate has more resonance forms and thus a lower free energy than linked phosphates 3. Orthophosphate has a more favorable interaction with the biological solvent (water) than linked phosphates ATP (Adenosine Triphosphate) The universal short-term energy storage molecule 5' cap A methylated guanine nucleotide added to the 5' end of eukaryotic mRNA. The cap is necessary to initiate translation of the mRNA. A band The band of the sacromere that extends the full length of the thick filament. The A band includes regions of the thick and thin filament overlap, as well as a region of thick filament only. A bands alternate with I bands to give skeletal and cardiac muscle tissue a striated appearance. The A band does not shorten during muscle contraction. Absolute Refractory Period A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation Absolute Threshold The minimum stimulus intensity required to activate a sensory receptor 50% of the time accessory glands the three glands in the male reproductive system that produce semen: the seminal vesicles, the prostate, and the bulbourethral glands Accessory Organs 1. GI Tract: Organs that play a role in digestion but are not part of the alimentary canal. The liver, gallbladder, pancreas and salivary glands 2. Reproductive System: any organ that is involved in reproduction that is not a gland (testis or ovary) Acetylcholine (ACh) The neurotransmitter used thorughout the parasympathetic nervous system as well as at the neuromuscular junction Acetylcholinesterase (AChE) The enzyme that breaks down acetylcholine in the synaptic cleft Acid Hydrolases Enzymes that degrade various macromolecules and that require an acidic pH to function properly; found within the lysosomes of cells Acinar Cells Cells that make up exocrine glands, and that secrete their products into ducts. For example: in the pancreas, acinar cells secrete digestive enzymes; in the salivary glands, acinar cells secrete saliva Acrosome A region in the head of a sperm cell that contains degestive enzymes which, when released during the acrosome reaction can facilitate penetration of the corona radiata of the oocyte and fertilization Actin