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Basic Biochemistry

Basic Biochemistry. Chemical Bonding. Covalent Bond - strong bond, formed by sharing of 2 or more electrons Example: C 6 H 12 O 6 & any organic molecules Ionic Bond – formed by the transfer of 1 or more electrons Example: NaCl & MgCl 2 Cation – positive Anion - negative. ….

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Basic Biochemistry

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  1. Basic Biochemistry

  2. Chemical Bonding • Covalent Bond - strong bond, formed by sharing of 2 or more electrons • Example: C6H12O6 & any organic molecules • Ionic Bond – formed by the transfer of 1 or more electrons • Example: NaCl & MgCl2 • Cation – positive • Anion - negative

  3. … 3. Hydrogen Bonding – weak bond formed by hydrogen w/i a molecule being attracted by oxygen & nitrogen w/i a molecule • Important in DNA and proteins

  4. Macromolecules of Life Abundance in a cell: • Proteins (55%) • Nucleic acids (24%) • Lipids (9%) • Carbohydrates (5%) • Lipopolysacharides (3%) • Other (4%) = inorganics

  5. Question: How Are Macromolecules Formed?

  6. HO H HO H H2O HO H Answer: Dehydration Synthesis • Also called “condensation reaction” • Forms polymers by combining monomers by “removing water”.

  7. Question: How are Macromolecules separated or digested?

  8. HO H H2O HO H HO H Answer: Hydrolysis • Separates monomers by “adding water”

  9. Lipids • Any biological molecule that has low solubility in water & high solubility in nonpolar organic solvents • Hydrophobic; thus they are good barriers for aqueous environments • 6 major groups: • Fatty acids • Tricylglycerols • Phopholipids • Glycolipids • Steroids • Terpenes

  10. Lipids … Fatty Acids • Building blocks for most complex lipids • Long chains with a carboxylic acid at 1 end • Can be saturated or unsaturated • Saturated only single C-C bonds • Unsaturated has one or more C=C (double bond) • Oxidation gives huge amounts of chemical energy for a cell

  11. Lipids … Triacylglycerols • A.K.A. triglycerides, fats, or oils • Have a 3 Carbon backbone (glycerol) that’s attached to 3 fatty acids • Function is to store energy, thermal insulation, and padding to an organism • Adipocytes (fat cells) contain almost nothing but triglycerides

  12. Lipids … Phospholipids • Glycerol backbone with one of the fatty acids replaced by a polar phosphate group • Major component of membranes • Amphipathic

  13. Lipids … Glycolipids • Phospholipid with one or more carbohydrates attached to glycerol rather than phosphate • Also amphipathic • Found in the membranes of myelinated cells of the nervous system

  14. Lipids … Steroids & Terpenes Steroids Terpenes • 4-ringed structure • Includes hormones, vitamin D, & cholesterol • Includes vitamin A (important for vision)

  15. Lipids are transported by lipoproteins in the blood • Classified by their density: (the greater the ratio of lipid to protein, the lower the density) • Very low density lipoproteins (VLDL) • Low density proteins (LDL) – ‘bad cholesterol’ • High density lipoproteins (HDL) – ‘good cholesterol’

  16. Proteins • Building block is amino acids linked together by a peptide bond • AKA polypeptides • Nearly all protein in all species are built from the same 20 amino acids • 10 are essential (ingested rather than manufactured by body) • Side chains differ from amino acid to amino acid

  17. Protein Structure Primary Structure Secondary Structure • Number and sequence of amino acids in a polypeptide • Single chain can twist into an α-helix or β-pleated sheets • Both are reinforced with H-bonds between amino acids

  18. Protein Structure… Tertiary Structure Quaternary Structure • 3-D shape formed when the peptide chain curls and folds • Created by 5 forces: • Covalent disulfide bonds b/w cysteine • Electrostatic ionic interactions (acidic & basic) • Hydrogen bond • Van der Waals forces • Hydrophobic side chains push away from water toward center

  19. Protein Structure… Quaternary Structure • 2 or more polypeptide chains bond together • Same 5 forces as tertiary

  20. A denatured protein has lost secondary, tertiary, and quaternary structure • Protein can sometimes form back when denaturing agent is removed • 2 main functions of proteins: • Structural (cell wall) • Functional (enzymes)

  21. 2 main types of proteins: • Globular (functional) • Enzymes • Hormones • Membrane pumps & channels • Membrane receptors • Intercellular and intracellular transport and storage • Osmotic regulators • Etc. • Structural – maintain and add strength to cells • Ex. Collagen

  22. … • Central Dogma DNA → RNA → protein ↑ ↑ transcription translation Genotype Phenotype

  23. Carbohydrates • AKA sugars or saccharides • Glucose accounts for 80% of carbs absorbed by humans • Liver converts most carbs to glucose • Glucose turned to ATP during cellular respiration • If cell has enough ATP, the glucose is turned to glycogen (only animals) or fat • Most cells absorb glucose via facilitated diffusion – insulin increases absorption rate • Plants form cellulose and starch from glucose

  24. Carbohydrates … • Building blocks are simple sugars (monosaccharides) • glucose, ribose, etc • Cell wall constituents (peptidoglycan) • Cell recognition factors in membranes • lipopolysaccharides • Serves as high energy storage compounds (glycogen) • Serve as bacterial ‘food’ (chemoheterotrophs)

  25. 2 monosaccharides make a disaccharide

  26. Monomer to disaccharide to polysaccharide

  27. Nucleic Acids • Building blocks are nucleotides: • 5-C Sugar, phosphate group, & nitrogen base • Nitogen bases: adenine, cytosine, guanine, thymine, uracil (a=t) & (c=g) & (a=u) • Nucleotides joined by phosphodiester bonds • Examples of nucleic acids include DNA, RNA, ATP, NADH, FADH2 • DNA is written 5’ to 3’

  28. Functions – information storage • RNA has multiple functions: • mRNA – RNA copy of DNA • rRNA – part of ribosome, helps to make proteins • tRNA – carries amino acids to ribosome

  29. Pop Quiz • A molecule of DNA contains all of the following except: • Deoxyribose sugars • Polypeptide bonds • Phophodiester bonds • Nitrogenous bases • Which of the following is a carbohydrate polymer that is stored in plants and digestible by animals? • Starch • Glycogen • Cellulose • Glucose

  30. …cont. • Excessive amounts of nitrogen are found in the urine of an individual who has experienced a period of extended fasting. This is most likely due to: • Glycogenolysis of the liver • The breakdown of body proteins • Lipolysis in adipose tissue • A tumor on the posterior pituitary causing excessive ADH secretion 4. Metabolism of carbohydrate and fat spare protein tissue. All of the following are true of fats except: • Fats may be used in cell structure • Fats may be used as hormones • Fats are more efficient form of energy storage than proteins • Fats are less efficient form of energy storage than proteins

  31. … cont. • Which of the following is found in the RNA but not the DNA of a living cell? • Thymine • Double helix • An additional hydroxyl group • Hydrogen bonds

  32. Answers • B • A • B • C • C

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