BIOCHEM-REVIEWER-MID-TERM.pdf

CHAPTER 1: Carbohydrates -About 75% mass of dry planet materials.  Functions in humans 1. Carbohydrates oxidation provides 1.1 BIOCHEMISTRY-AN OVERVIEW...

CHAPTER 1: Carbohydrates -About 75% mass of dry planet materials.  Functions in humans 1. Carbohydrates oxidation provides 1.1 BIOCHEMISTRY-AN OVERVIEW energy. Biochemistry – study of the chemical 2. Storage, in the form of glycogen, substances found in the living organisms provides a short energy reserve. and the chemical interactions of these 3. Supply carbon atoms in other substances with each other. biomolecules. 4. From pat of structural framework Biochemical substance – chemical of DNA and RNA molecules. substances found within a living 5. Structural components of cell organism. membranes  Bioinorganic substances 6. Linked to protein function in a - Water (70%) variety of cell-cell and cell- - Inorganic salt (5%) molecule recognition process.  Bioorganic substances - Protein (15%) - Lipids (8%) 1.3 CLASSIFICATION OF - Carbohydrates (2%) CARBOHYDRATES - Nucleic acids (2%) -General formula CnH2nOn or Cn(H2O)2  Carbohydrates is a polyhydroxy 1.2 OCCURRENCE AND FUNCTION OF aldehyde or a polyhydroxy CARBOHYDRATES ketone. -Carbohydrates are one of the most abundant class of bioorganic molecules on planet earth.  Monosaccharide  - Contains a single polyhydroxy - Ex., cellulose, starch aldehyde or ketone unit. - Cannot be broken down by hydrolysis. - Ex. Glucose, fructose 1.4 CHIRALITY: Handedness of - Naturally occurring Molecules monosaccharide have from 3- - Handedness is a form of 7 carbon atoms. isomerism *left-handedness *right-handedness  Disaccharide - Contains 2 monosaccharide units covalently bonded to  MIRROR IMAGES each other. - Is the reflection of an object in - Ex. Sucrose, lactose a mirror. Superimposable mirror images  Oligosaccharide – coincide at all points when the - 3 -10 monosaccharides images are laid upon to each - Usually found associated with other. proteins and lipids Nonsuperimposable – not all - Through hydrolysis can points coincide when the images produce multiple are laid upon each other. monosaccharides  CHIRALITY  Polysaccharide - Requirement of handedness is - Polymeric carbohydrates than the presence of a carbon atom contains many that has 4 different groups monosaccharides bonded to it in a tetrahedral - undergo hydrolysis under orientation. appropriate conditions  - Chiral center – handedness - generating carbon atom. 1.6 DESIGNATED HANDEDNESS USING FISCHER PROJECTIONS FORMULA - Chiral molecule – molecules  Fischer Projection Formula – a whose mirror images are not 2-dimensional structural notation superimposable. for showing the spatial - Achiral molecule – molecules arrangement of groups about whose mirror image is chiral centers in molecules. superimposable. 1.5 STEREOISOMERISM: Enantiomers & Diastereomers  D, L system used to designate the handedness glyceraldehyde enantiomers is extended to  Stereoisomers – Are isomers monosaccharides with more than that have the same molecular & one chiral center in the lower structural formulas but differ in the manner. orientation of atoms in a space.  Epimers – diastereomers whose molecules differ only in the TYPES OF STEREOISOMERS: configuration at one chiral center.  Enantiomers – stereoisomers whose molecules are 1.7 PROPERTIES OF ENANTIOMERS nonsuperimposable mirror images  Optically active compound – of each other. compound that rotates the plane  Diastereomers – molecules are polarized light. not mirror images of each other.   Dextrorotatory – enantiomers  D-Glyceraldehyde & that rotates plane polarized light in Dihydroxyacetone the clockwise direction. - The simplest of the monosaccharides.  Levorotatory – rotate at - These 2 trioses are important counterclockwise direction. intermediates in the process of glycolysis. - D-Glyceraldehyde is chiral 1.8 CLASSIFICATION OF molecule, but MONOSACCHARIDES Dihydroxyacetone is achiral.  ALDOSE – monosaccharide that contains an aldehyde functional group.  D-Glucose - Is the most abundant in nature  KETOSE – Monosaccharide that and most important from contains ketone as functional human nutritional standpoint. group. - Other name is dextrose and blood sugar. - 70-100 mg/ dl -normal concentration of glucose in the human body. 1.9 BIOCHEMICALLY IMPORTANT MONOSACCHARIDES  D-Galactose - From the 3rd – 6th carbon, the - D-galactose and D-glucose structure of D-fructose differ only in the configuration identical to that D-glucose. of the -OH group and -H group - Difference at carbon 1 and 2. in carbon 4. - D-galactose is seldom encountered as a free  D-Ribose monosaccharide. - D-Ribose is a pentose - Galactose is synthesized from - Component of a variety of glucose in the mammary complex molecules, including glands for use in lactose. RNAs & DNAs and energy-rich - Sometime called brain sugar. compound such as ATP.  D-Fructose - Biochemically the most important ketohexose. - Known as levulose and fruit 1.10 CYCLIC FORMS OF sugar. MONOSACCHARIDES - D-fructose is found in many - The cyclic forms of fruits and is present in honey in monosaccharides result from equal amounts with glucose. the ability of their carbonyl - Sometimes used as dietary group to react intermolecularly sugar with hydroxyl group. - Decreased in sucrose – increased in fructose.  - The resulting cyclic compounds are cyclic 1.12 REACTIONS OF hemiacetals. MONOSACCHARIDES  OXIDATION REACTION - Weak Oxidation rxn – oxidize the aldehyde end of an aldose to give an aldonic acid.  Carbon Atom – the hemiacetal carbon atom present in the cyclic monosaccharide structure.  Cyclic monosaccharide formation always produces two stereoisomers – alpha form or beta form. - Strong Oxidation Rxn – can  Anomers – cyclic oxidize both ends of monosaccharide that differ only in monosaccharide at the same the positions of substituents on time (carbonyl group & the anomeric carbon atom. terminal primary alcohol group). 1.11 HAWORTH PROJECTION FORMULAS - Enzymatic Oxidation Rxn –  Two-dimensional structural Enzymes can oxidize the notation that specifies the three- primary alcohol end of an dimensional structure of cyclic aldose such as glucose, with from of monosaccharide. oxidation of the aldehyde  group to produce alduronic acid.  PHOSPHATE ESTER FORMATION - The hydroxyl groups of monosaccharide can react  REDUCTION REACTION TO with inorganic oxyacids to form PRODUCE SUGAR ALCOHOL inorganic ester. - Product of the reduction is the corresponding polyhydroxy alcohols. Such as polyhydroxy called sugar alcohols or alditols.  AMINO SUGAR FORMATION - If one of the hydroxyl groups of monosaccharide is replaced with an amino group, an amino sugar is produced.  GLYCOSIDE FORMATION - Hemiacetal were shown to react with alcohols in acid solution to produce acetals. - Glycoside – is an acetal form a cyclic monosaccharide by replacement of hemiacetal LIPIDS o An organic compound found in the living carbon –OH group with an -OR organisms that is insoluble (or only sparingly soluble) in water but soluble in group. nonpolar solvents. o Unlike other biomolecules, lipids do not - Some are Esters, some are amides, have common structural feature that & some are alcohols (acyclic, cyclic, serves as the basis for defining such & polycyclic). compounds. CHARACTERISTICS OF LIPIDS 1. Lipids are mostly hydrophobic. 2. Made up of mostly C-H bonds. 3. Useful for long term energy storage. 4. Make up the membranes of cells. 5. Provides thermal insulation & protection. CLASSIFICATION BASED ON BIOCHEMICAL FUNCTION 1. Energy-storage lipids (Triacylglycerol)  TYPES OF FATTY 2. Membrane lipids (phospholipids, sphingoglycolipids, & cholesterol) ACIDS 3. Emulsification lipids (bile acids) - Naturally occurring monocarboxylic 4. Messenger lipids (steroid hormones acids (COOH). & eicosanoids) - Nearly always contain an even 5. Protective-coating lipids (biological number of C atoms and a carbon waxes) chain that is unbranched. *Long-chain fatty acids (C12- C26) CLASSIFICATION BASED ON *Medium-chain fatty acids (C8- SAPONIFICATION C10) *Short-chain fatty acids (C4- C6) Saponification reaction- hydrolysis - - Long chains of hydrocarbons that reaction that occurs in basic solution. contains carboxylic acid functioning group at the end. 1. Saponifiable lipids – triacylglycerol, phospholipids, sphingoglycolipids, cholesterol & biological waxes. SATURATED FATTY ACIDS (SFA) -Saponifiable lipids are converted into 2 or more smaller molecules when hydrolysis occurs. 2. Nonsaponifiable lipids – bile acids, Carboxylic steroid hormones, & eicosanoids. -Nonsaponifiable cannot be broken down into smaller units since they - A fatty acid with carbon chain in which cannot react with water. all carbon-carbon bonds are single bonds. STRUCTURAL DIVERSITY OF MONOUNSATURATED FATTY ACID LIPIDS (MUFA)  between 9 & 10, 12 & 13, and 15 & 16).  TYPES OF UNSATURATED FATTY ACIDS - MUFA is a fatty acid with carbon chain in which 1 carbon-carbon Omega (ω)-3 fatty acids – Unsaturated double bond. fatty acids with its endmost double bond - Prescence of cis double bond. 3 carbon atoms ways from tis methyl end. POLYUNSATURATED FATTY ACID (PUFA) - PUFA is a fatty acid with a carbon chain in which 2 or more carbon- carbon double bonds are present. Omega (ω)-6 fatty acids – Unsaturated - IUPAC names for fatty acids. fatty acids with its endmost double bond e.g., IUPAC name: cis,cis- 6 carbon atoms away from methyl end. 9,12-octadecadienoic acid – means there is double bond in carbon 9 &12. TRANS UNSATURATED FATTY ACID  PHYSICAL - The H atoms on the double bond are on opposite sides. PROPERTIES OF FATTY ACIDS Water Solubility – direct function of carbon chain length; solubility decreases as carbon chain length increases. Short-chain fatty acids – Slightly soluble. o Related to the polarity of carboxyl group present.  UNSATURATED FATTY ACIDS & DOUBLE-BOND POSITION - Numbering starts from the other end of -COOH. - Structural notation indicates number of atoms. 18:2 Number of Carbon Number of double bonds - The notation 18:3 (Δ9,12,15) – C18 PUFA w/ 3 double bonds at location  *Carbohydrate glycerol – widespread energy-storage materials within the cells. - Major energy-storage material than glycogen because large quantities of them can be packed into very small Long-chain fatty acids – insoluble in volume. water. o The nonpolar nature of - In terms of functional group present, hydrocarbon chain triacylglycerols are triesters (3 ester completely dominates functional group are present). solubility consideration. - The alcohol involved in triacylglycerol Melting point – Strongly influenced by is always glycerol (3-carbon alcohol both carbon chain length and degree of w/ 3 hydroxyl group). unsaturation. - As carbon chain length increases, Esterification reaction – a single melting point increases. molecule of glycerol reacts with 3 fatty - Long-chain saturated fatty acids acids. tend to be solids at room temperature. - Long-chain unsaturated fatty acids tend to be liquids at room temperature. - Number of “bends” in a fatty acids chain increases as the number of double bonds increases. - Acyl group – the portion of a carboxylic acid that remains after - OH group is removed from the  ENERGY-STORAGE carboxyl carbon atom. LIPIDS: TRIACYGLYCEROLS - Exception of nerve cells, human cells store small amounts of energy- providing materials for use when energy demand is high. - To make it we need dehydration  TWO TYPES OF synthesis rxn. TRIACYLGLYCEROLS Simple Triacylglycerol – Triester MUFA formed from the esterification of glycerol - “Good fats” w/ 3 identical fatty acid molecules. - Decrease both heart disease & breast cancer risk. - Help reduce the stickiness of blood platelets, prevent formation of blood clot. - Olive, avocado, canola oils. PUFA Mixed Triacylglycerol - Triester formed - Both “good fats” & “bad fats” from the esterification of glycerol w/ more than 1 kind fatty acid molecules. Current recommended amount for total fat intake in calories: - 15% - MUFA - 10% - PUFA -