Online Test 1 Flashcards
Classification of carbohydrates
- Monosaccharides
- Disaccharides
- Oligosaccharides
- Polysaccharides
Carbohydrate Functions
- Metabolism
- Structural
- Precursor of DNA and RNA
- Cell Surface Marker
Metabolism
- Fuel
- Storage
Structural
- Scaffolding of bacterial and plant cell wall
- Exoskeleton of arthropods
- Lubricative coating between cells
Precursor of DNA & RNA
- Serves a chemical structural role
- Polar site for catalytic processes of RNA
Cell Surface Marker
- Immune protection/recognition
- Cell-Cell recognition
- Host Pathogen Interaction
Common Carbohydrates Structure
- D-ribose
- D-galactose
- D-glucose
Chemical Properties of Carbohydrates
- at least 1, often 2 or more asymmetrical centres
- exists in either linear or cyclic
- form polymers via glyosidic bond
- forms multiple hydrogen bonds with H2O
Carbohydrate Reactions
- Oxidation Reduction: metabolic breakdown
- Esterification: phosphate
- Amino Derivative: structural components & glycoprotein
- Glyosidic formation: form polysaccharides
Identification
Maltose: α-D-glucose and β-D-glucose, α (1 > 4) linkage
Cellobiose: β-D-glucose and β-D-glucose, β (1 > 4) linkage
Lactose: β-D-galactose and β-D-glucose, β (1 > 4) linkage
Sucrose: α-glucose and β-fructose, α (1 > 2) linkage
Carbohydrate Polysaccharides
- Carbohydrate Polymer
- Storage Polysaccharide
- Structural Polysaccharide
- Structural Peptidoglycans
Lipids Classification
- Simple
- Complex
- Derived
Simple Lipids
Ester-containing lipids with 2 types of components: an alcohol and 1 type of fatty acid
Complex Lipids
Ester-containing lipids with more than 2 types of components: an alcohol, fatty acids and other components
Derived Lipids
formed via metabolic transformation of fatty acids
Components of Simple lipids
- long chain carboxylic acids
- Characteristics of fat depends on proportion and type of fatty acid, and their arrangement on the glycerol molecule
- Fatty acids found in natural fats usually contain an even no. of carbon atoms
- Free fatty acids are rare in nature
Lipid Structure
-Long chain monocarboxylic acids
-Amphiphilic molecule
• Hydrocarbon (CH) group: non -polar
• COOH group: polar
-Size Range: C4-C36. Normally in nature C12 - C24
-Always an even number of carbon.
Reaction of fatty acids
- Esterification
- Hydrolysis
- Acid-base
- Addition (for unsaturated)
Esterification of fatty acids
1 Glycerol + 1 FA Monoglyceride + water
1 Monoglyceride + 1 FA Diglyceride + water
1 Diglyceride + 1 FA Triglyceride + water
Formation of triglycerid/ triacylglycerol
- Esterification of glycerol and fatty acids
- Simple triglycerides are rare,
- Hence, triglycerides can form optical isomers.
Glycolipid Function
- Production of cell membranes
- Emulsifying agents
Physical & Chemical Properties of Lipids
- Melting Point
- Specific Gravity
- Solubility
- Colour
- Saponification
Melting Point of Lipids
- Melt gradually or in stages, depending on the types of triglyceride molecules.
- Melting point of fatty acids increases with increasing chain length
Solubility of Lipids
- Solubility of fats & fatty acids in water decreases with increasing chain length
- Phospholipid & glycolipid molecules are more soluble in polar solvents (due to polar heads) than triacylglycerol
Specific Gravity of Lipids
– Less than 1 (about 0.9)
– Increases with decreasing molecular weight and increasing unsaturation
Colour of Lipids
-Usually yellow/ white, and are odourless and tasteless
Saponification of Lipids Formula
Hydrolysis of fats in alkaline conditions:
3H2O + Fats/Oils = 3 fatty acids + glycerol
3 Fatty acids + 3NaOH = 3 Na salts + 3 H2O
Saponification
- Heating of a fat with strong base to produce glycerol and the salt of a fatty acid
- The sodium/ potassium salt of a fatty acid is called soap
- The long chain aliphatic part is nonpolar , and the carboxylate part is polar
- Soap emulsifies greases for easier removal
- Soap lowers the surface tension of water for easier emulsification
Rancidity of Lipids
- Hydrolytic rancidity
- Oxidative rancidity
Oxidative Rancidity
- Occurs when the double bonds in unsaturated fats oxidize
- Causes double bonds to rupture and form pungent and volatile aldehydes
Hydrolytic Rancidity
- Occurs due to contact with moist air
- Moist air carrying Lipase causes the catalysis of hydrolysis
Cholesterol
- Principal membrane lipid for fluidity
- Amphiphilic
Function of Lipoprotein
transportation and delivery of fatty acids, triacylglycerol, and cholesterol
Cholesterol
- Associated with hardening of the arteries
- Plaque formation
- Increased blood pressure from:
• Narrowing of arteries
• Reduced ability to stretch - Myocardial Infarction
- Stroke
Thromboxane A2
- Produced by platelets in blood
- Stimulates constriction of blood vessels
- Aggregation of platelets
Prostacyclin
- Produced by cells that line blood vessels
* Reverses effects of Thromboxane A2
Plasma Membrane Functions
- Protective
- Structural integrity
- Selective entry & exit of metabolites in & out of cell
- Communication by receptors
- Energy transduction
Function of Proteins
- Enzyme: increases rate of biochemical reaction
- Transport: transport oxygen and proteins in blood
- Signaling: signals hormones to regulate growth & development, and maintain body homeostasis
- Contractile: bodily movement
- Defend: produce antibodies to help fend off against viruses
- Structural: Hair, Keratin, Ligament etc.
Characteristics of 20 amino acids
- monomers
- differ in side chain
Peptide bond
how the amino acids are linked together to make a protein
Classification of amino acids
Group I: non-polar
Group II: polar, uncharged
Group III: acidic
Group IV: alkaline
Classification of Proteins
- Simple: only contains amino acids
- Conjugated: contains other biomolecules (etc. prosthetic group)
Structure of Proteins
- Primary: linear sequence of amino acids linked by polypeptide
- Secondary: α-helix and β-pleated sheet held by hydrogen bond
- Tertiary: Interaction of side chains - folding into 3 dimensional shapes held by hydrogen bond
- Quaternary: association of two or more polypeptide chains to form a multi-subunit molecule
Tertiary Structure
- Polypeptide chains fold spontaneously so that majority of the hydrophobic chains are buried inside, while the hydrophilic, polar, and charged side chains are on the surface
- Maintain conformation with hydrophobic interactions, electrostatic forces, hydrogen and disulfide bond
Quaternary Structure
- Interaction with 2 or more polypeptide chains to associate and form a larger protein molecule
- Many proteins are not a single strand
- Held by weak, non-covalent bonds: Hydrogen, disulfide, ionic, and hydrophobic bonds
Enzymes
- High activation Energy, slow reaction rate
- Catalyst decreases activation energy
Enzyme Cofactor
- Additional component to function correctly
- Zinc, Copper or Magnesium etc
Classification of Enzymes
- Oxidoreductase: catalyze redox reaction
- Transferase: transfer a functional group
- Hydrolase: cause hydrolysis reaction
- Lyase: break C-O, C-N or C-C bonds
- Isomerase: rearrange functional groups
- Ligase: join two molecules
Enzyme activity factors
- Environmental factors
- Cofactors
- Inhibitors
Enzyme Reaction
- Enzyme + Substrate = Complex
- Complex goes through transition state
- Enzyme complex and product produced
Types of inhibitors
- Reversible: deactivates enzyme when present, weak, non covalent bonds
- Irreversible: attacks relevant amino acid group, forms strong covalent bonds
Three other types of inhibitors(?)
- Competitive
- Non-competitive
- uncompetitive
Rate of enzyme reaction
-Conc of substrate increase, rate of reaction increases until point of saturation
Function of Lipids
- Energy Storage
- Biological membranes
- Hormone productive
Energy storage
Triglyceride breakdown yields more energy than the breakdown of carbohydrates due to hydrogen bonds
Biological membrane
Composed of a phospholipid bolster
Hormone production
Steroid hormones important for signalling molecules that can enter the cell directly through cell membrane
