Biochemistry Past Paper PDF

BIO 024: Biochemistry First Semester┃S. Sarcol #1: CARBOHYDRATES Carbohydrate glucose - is a polyhydroxy aldehyde Carbohydrates - are the most abundant class...

BIO 024: Biochemistry First Semester┃S. Sarcol #1: CARBOHYDRATES Carbohydrate glucose - is a polyhydroxy aldehyde Carbohydrates - are the most abundant class Carbohydrate fructose - is a polyhydroxy of bioorganic molecules on planet Earth ketone Constitute about 75% by mass of dry plant CLASSIFICATION OF CARBOHYDRATES materials. Green (chlorophyll-containing) plants 1.) Monosaccharide - sugars with one molecule produce carbohydrates by photosynthesis Cannot be hydrolyze further Considered as the building block of carbohydrate Examples: Glucose and Fructose Often called as sugars 2.) Disaccharide - sugars that contains two monosaccharide units covalently bonded to each other Example: Sucrose and Galactose In this process, carbon dioxide from the air and 3.) Oligosaccharide - sugar that contains 3 to 10 water from the soil are the reactants, and sunlight monosaccharides unit absorbed by chlorophyll is the energy source. Example: Raffinose TWO MAIN USES OF CARBOHYDRATES BY Two naturally occurring oligosaccharides THE PLANTS: found in onions, cabbage, broccoli, brussel sprouts, whole wheat, and all 1.) As a structural component (Cellulose) types of beans 2.) As an energy reserve (Starch) 4.) Polysaccharide - polymeric carbohydrate that Dietary intake of plant materials is the major contains many monosaccharides units covalently carbohydrate source for humans and animals. bonded to each other The average human diet should ideally be about two-thirds carbohydrate by mass Example: Starch Often called as glycans FUNCTIONS OF CARBOHYDRATES IN HUMANS 1.) Provides energy through oxidation process MOLECULAR STRUCTURES OF CARBOHYDRATES 2.) Supply carbon atoms First, an important property of many molecules, 3.) Linked to lipids are structural components of including most carbohydrates, is “handedness,” cell membranes which is a form of isomerism. 4.) Provides a short-term energy reserve 5.) Structural framework of DNA and RNA Molecules that possess “handedness” exist molecules in two forms: a “left-handed” form and a 6.) Linked to proteins function in a variety of “right-handed” form cell–cell and cell–molecule recognition processes Superimposable Mirror Images (Achiral) - are A carbohydrate (Cn(H2O)n) is a polyhydroxy images that coincide at all aldehyde, a polyhydroxy ketone, or a compound points when the images that yields polyhydroxy aldehydes or polyhydroxy are laid upon each other ketones upon hydrolysis Achiral molecule is a molecule whose mirror images are superimposable. Achiral molecules do not possess handedness. |1 BIO 024: Biochemistry First Semester┃S. Sarcol Nonsuperimposable Mirror Images (Chiral) - are Levorotatory Compound - a chiral compound images where not all points coincide when the that rotates the plane of polarized light in a images are laid upon each other. counterclockwise (levo = “left”) Chiral molecule is a molecule whose mirror images are not superimposable Chiral molecules have handedness Chiral center - is an atom in a molecule that has four different groups bonded to it in a tetrahedral orientation A molecule that contains a chiral center is said to be chiral HAWORTH PROJECTION FORMULA REQUIREMENTS TO HAVE A “CHIRAL” MOLECULE A Haworth Projection Formula is a two-dimensional structural notation that specifies 1.) If the bonds from the center atom to the four the three-dimensional structure of a cyclic form of a different groups are all single bonds monosaccharide 2.) A chiral center is an atom in a molecule that has four different groups bonded to it in Pyranose - cyclic monosaccharide a tetrahedral orientation. In this part, containing a six-atom ring carbon is seen as the Chiral center Furanose - one containing a five-atom ring 3.) A chiral molecule is a molecule whose mirror images are not superimposable. Anomeric Carbon Atom - is the hemiacetal 4.) Chiral molecules have handedness. carbon atom present in a cyclic monosaccharide structure REACTIONS OF MONOSACCHARIDE 1.) Oxidation to Produce Acidic Sugars a. Aldonic Acid Acid group on top STEREOISOMERISM Uses weak oxidizing agent b. Alduronic Acid Stereoisomers - are isomers that have the Acid group on bottom same molecular and structural formulas but differ Uses enzymes in the orientation of atoms in space c. Aldaric Acid Both top and bottom Enantiomers - are nonsuperimposable Uses strong oxidizing agent mirror images of each other Diastereomers - are stereoisomers whose 2.) Reduction to Produce Sugar Alcohols molecules are not mirror images of each 3.) Glycoside Formation other 4.) Phosphate Ester Formation 5.) Amino Sugar Formation FISCHER PROJECTION FORMULA PARAMETERS TO DISTINGUISH POLYSACCHARIDES: A Fischer Projection Formula is a two-dimensional structural notation for showing 1.) The identity of the monosaccharide the spatial arrangement of groups about chiral repeating unit(s) in the polymer chain centers in molecules. a. Homopolysaccharide - only one Named after Emil Fischer type of monosaccharide monomer b. Heteropolysaccharide - with more Optically Active Compound - is a compound than one (usually two) type of that rotates the plane of polarized light monosaccharide monomer 2.) The length of the polymer chain Dextrorotatory Compound - is a chiral 3.) The type of glycosidic linkage between compound that rotates the plane of polarized light monomer units in a clockwise direction (dextro = “right”) |2 BIO 024: Biochemistry First Semester┃S. Sarcol 4.) The degree of branching of the polymer To lend mechanical support and flexibility to chain tissue to help form skin and cartilage TYPES OF POLYSACCHARIDES 3.) Dermatan Sulfate (DS) - closely related GAG 1.) Storage Polysaccharides - used as an energy Structural polysaccharide in skin source in cells. Examples are starch and glycogen. 4.) Keratan Sulfate (KS) - formed from alternating Starch - plants units of galactose and sulfated N-acetylgucosamine Glycogen - animals aka animal starch OTHER NATURAL POLYSACCHARIDE OF INTEREST 2.) Structural Polysaccharides - serves as a structural element in plant cell walls and animal 1.) Agar - linear polymer of sulfated and unsulfated exoskeletons like chitin and cellulose galactose prepared form marine algae – agarose Cellulose - the structural component of When dissolves in hot water and then plant cell walls. It is the most abundant cooled, it forms gels naturally occurring polysaccharide Not a proteoglycan but is purely Chitin - the 2nd most abundant naturally carbohydrate occurring polysaccharide, next to cellulose. Also used as food additive to chicken liquid Function is to give rigidity to the suspensions exoskeletons of crabs, lobsters, shrimp, insects, and other arthropods. 2.) Inulin - is a polysaccharide of fructose 3.) Acidic Polysaccharides - a disaccharide Readily soluble in water and is used to repeating unit in which one of the disaccharide determine the glomerular filtration rate components is an amino sugar and one or both disaccharide components have a negative charge 3.) Dextrins - are intermediates in the hydrolysis of due to a sulfate group or a carboxyl group. starch. Example: hyaluronic acid & heparin CARBOHYDRATE RELATED DISEASES: SPECIAL GROUP: DIABETES 1.) Glycosaminoglycans (GAGS) (aka It is a chronic (long-lasting) health condition that mucopolysaccharides, or negatively charged affects how your body turns food into energy. polysaccharides) - are large linear polymers of repeating disaccharide units. Most of the food you eat is broken down into sugar (also called glucose) and Location: released into your bloodstream. When your blood sugar goes up, it signals your a. Found outside the cells pancreas to release insulin. b. Cell surface If you have diabetes, your body either c. Part of extracellular matrix doesn’t make enough insulin or can’t use d. Attached to the protein core to form the insulin it makes as well as it should proteoglycans. SYMPTOMS OF DIABETES (THE 3Ps) EXAMPLES OF GLYCOSAMINOGLYCANS (GAGS) 1.) Polyuria – increase urination 1.) Heparin Sulfate (HS) - sulfated polysaccharide 2.) Polydipsia – increase thirst found as a component of cell-surface 3.) Polyphagia – increase eating due to proteoglycans as a component of cell-surface hunger proteoglycans in mast cells and in the surface TYPES OF DIABETES of endothelial cells lining blood vessels 1.) TYPE 1 - most diagnosed in children and NOTE: Heparin is much smaller than heparin teenagers. It’s an autoimmune condition. sulfate and that is not linked to a protein core. 2.) TYPE 2 - happens when your body stops responding to the insulin your pancreas 2.) Chondroitin Sulfate (CS) - structural makes polysaccharide of ligaments, cartilage and tendons 3.) GESTATIONAL - response to the hormonal changes that happen during pregnancy |3 BIO 024: Biochemistry First Semester┃S. Sarcol GALACTOSEMIA It is a rare, hereditary disorder of carbohydrate metabolism that affects the body’s ability to convert galactose to glucose. Galactose is a sugar contained in milk, including human mother’s milk as well as other dairy products |4