BIOCHEM WEEK 3 Flashcards by arabella erivera

• most abundant class of bioorganic molecules on planet Earth

Carbohydrates

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CHO in plants

– structural elements

Cellulose

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CHO in plants

energy reserve

Starch

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provides energy.

Oxidation

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Storage

glycogen

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– for synthesis of other biologic substances

C atom source

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DNA and RNA structural component

ribose & deoxyribose

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Cell membrane component

glycolipids

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Cell-cell and Cell-Molecule recognition processes

glycoprotein

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largest source of dietary calories for most of the world’s population

Carbohydrates

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• A carbohydrate that contains a single polyhydroxy aldehyde or polyhydroxy ketone unit or
• Cannot be broken down into simpler units by hydrolysis
• Usually contains 3-7 carbon atoms
• Water-soluble
• Crystalline solids

MONOsaccharide

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• 2 monosaccharides covalently bonded to each other
• Produces monosaccharides upon hydrolysis
• Water-soluble
• Crystalline

DIsaccharide

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• 3-10 monosaccharides covalently bonded to each other
• Produces monosaccharides upon hydrolysis
• Mostly not digested by human enzymes
Examples
• Raffinose • Stachyose

OLIGOsaccharide

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• MANY monosaccharides covalently bonded to each other
• Produces monosaccharides upon hydrolysis
Examples
• Glycogen • Cellulose • Starch

POLYsaccharide

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• name ends in –ose
§ except: Glyceraldehyde &
Dihydroxyacetone
• can be classified based on
§ number of carbons v Triose
v Tetrose v Pentose v Hexose
§ functional group v Aldose
v Ketose

Monosaccharides

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have the same molecular and structural formulas but differ in orientation of atoms in space

The left and right-handed forms of a chiral molecule

isomers

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nonsuperimposable mirror images
e.g. left- and right-handed forms of a molecule

Enantiomers

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not mirror images of each others

Diastereomers

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Type of isomerism founds in carbohydrates

§ Superimposable
§ Non-superimposable

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– C atom bonded to 4 different groups

Chiral Center

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(t or f)

• All proteins, most fats, and all common carbohydrates are chiral

true

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are almost always right-handed

Monosaccharides

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are always left-handed

Amino acids

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2D notation for showing the spatial arrangement of groups about chiral centers in molecules
• Chiral center is represented as the intersection of vertical and horizontal lines

Fischer Projection

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(t or f) § D stands for Dextro – right § L stands for Levo - left

true

Isomers in which the atoms have different connectivity

Constitutional Isomers

isomers with atoms of the same connectivity that differ only in the orientation of the atoms in space

Stereoisomers

Stereoisomers Stereoisomers that are non superimposable mirror images of each other. Handedness (D and L forms) is determined by the configuration at the highest- numbered chiral center

Enantiomers

Stereoisomers Stereoisomers that are nit mirror images of each other.

diastereomers

(t or f) Enantiomers are OPTICALLY ACTIVE – it rotates the plane of polarized light • If it rotates the plane polarized light towards the RIGHT (clockwise) → + DEXTROROTATORY • If it rotates the plane polarized light towards the LEFT (counter clockwise) → - LEVOROTATORY

true

(t or f) Handedness (D & L) of enantiomers & the direction of light rotation are NOT connected entities

true

The two members of an enantiomeric pair have the SAME interaction with __________________

ACHIRAL molecules

The two members of an enantiomeric pair have DIFFERENT interactions with __________________

CHIRAL molecules

• Name due to its resemblance to the cyclic ether Pyran • Cyclic monosacchoride containing a 6-atom ring

PYRANOSE

• Name due to its resemblance to the cyclic ether Furan • Cyclic monosacchoride containing a 5-atom ring

FURANOSE

• 2D structural notation that specifies the 3D structure of the cyclic form of a monosaccharide • hemiacetal ring system viewed “edge on” with the –O– ring atom at the § upper right (6 membered ring) or § top (5-membered ring)

Haworth Projection

can yield 3 different types depending on the oxidizing agent

Oxidation

Yields polyhydroxy alcohols referred to as ___________

ALDITOLS

(t or f) Hydroxyl groups (–OH) can react with inorganic oxyacids to form inorganic esters

true

Amino sugars and their N-acetyl derivatives are building blocks of glycosaminoglycans such as ___________

hyaluronic acid

(t or f) • Hydroxyl group (–OH) of a monosaccharide is replaced with an amino group (NH2) • In naturally occurring amino sugars, NH2 replaces the C2 –OH group

true

Fact: the cyclic form of monosaccharides are ___________

hemiacetals

–OH group is replaced with an –OR group

Hemiacetal carbon

(grape sugar) • Most abundant in nature • Nutritionally the most important • Used by cells as the primary source of energy

GLUCOSE

(brain sugar) • Seldom encountered as a free monosaccharide • Synthesized in the mammary glands for use in lactose (milk sugar) • Component of glycoproteins found in nervous tissue • Also present in the chemical markers that distinguish various blood types

GALACTOSE

glucose optically active

Dextrose

glucose blood contains dissolved glucose § Insulin - ↓ glucose level § Glucagon - ↑ glucose level

Blood sugar

(fruit sugar) • Most important ketohexose • Sweetest-tasting of all sugars • Sometimes as a dietary sugar because it requires a smaller amount to reach the same amount of sweetness

FRUCTOSE

Fructose optically active

Levulos

• Pentose • Important component of RNA and energy-rich compounds

RIBOSE

• Important component of DNA molecules • lacks an Oxygen atom at the 2nd carbon compared to ribose

DEOXYRIBOSE

• Malt sugar • Produced by the breakdown of the polysaccharide starch • Common ingredient in baby foods and malted milk • 1 glucose + 1 glucose linked by an ⍺(1→4) linkage • Can be broken down by the enzyme maltase

Maltose

• Milk sugar • Synthesized by mammalian mammary glands by in a 4 step process • Common ingredient in commercially-produced infant formula • 1 glucose + 1 lactose linked by a β(1→4) linkage • Can be broken down by the enzyme lactase

Lactose

• Table sugar • Most abundant disaccharide • Commercially produced from sugar cane and sugar beets • 1 glucose + 1 fructose linked by a β(1→2) linkage • Can be broken down by the enzyme sucrase • NONREDUCING

Sucrose

• Also referred to as Glycans • Polymer that contains many monosaccharide units bonded to each other by glycosidic linkages • Not sweet, not positive for Tollen’s or Benedict’s Test • Limited water solubility - –OH groups can individually become hydrated, resulting in thick colloidal suspensions of polysaccharides § Used as thickening agents in sauces, desserts, and gravy

Polysaccharide

The identity of repeating monosaccharide units only 1 type of monosaccharide

Homopolysaccharides

The identity of repeating monosaccharide units two or more types of monosaccharide

Heteropolysaccharide

• Energy storage homopolysaccharide found in PLANTS • Composed solely of glucose units • Amylose – unbranched (15-20%) bonds: ⍺(1→4) MM: 50,000 (up to 1k glucose units) Amylopectin – branched (80-85%) bonds: ⍺(1→4) ⍺(1→6) at branch points every 25-30 units MM: 300,000 (up to 100k glucose units) • Hydrolyzed by enzymes of the human digestive tract

STARCH

• Energy storage homopolysaccharide found in ANIMALS & HUMANS • Composed solely of glucose units • Stored in the liver and muscle • Bonds: ⍺(1→4) ⍺(1→6) at branch points • MM: 3,000,000 (up to 1M glucose units)

GLYCOGEN

• Structural homopolysaccharide found in PLANT CELL WALL • Monomer: glucose • Bonds: β(1→4) • Most abundant polysaccharide • NOT hydrolyzed by enzymes in the human digestive tract • Serves as dietary fiber – readily absorbs water leading to softer stools

CELLULOSE

• Structural homopolysaccharide found in ARTHROPODS & FUNGI • Monomer: N-acetyl-D-glucosamine Bonds: β (1→4) • 2nd most abundant polysaccharide • NOT hydrolyzed by enzymes in the human digestive tract

CHITIN

• Alternating residues of N-acetylglucosamine and D-glucuronic acid • Bonds: β(1→3) alternating with β(1→4) • 50,000 disaccharide units/chain • Found as lubricant fluid of joints and in the vitreous humor of the eye

HYALURONIC ACID

• Alternating residues of Sulfated iduronic acid and Sulfated glucosamine • Blood anticoagulant naturally present in mast cells & is released at the site of tissue injury • Used therapeutically to inhibit coagulation of blood

HEPARIN

• lipid molecule that has ≥ 1 carbohydrate (or derivative) units covalently bonded to it Functions • Cerebrosides & Gangliosides – found extensively in neural tissue • Essential cell membrane component

Glycolipids

• protein molecule that has ≥ 1 carbohydrate (or derivative) units covalently bonded to it Functions • Immunoglobulins • Cell surface recognition and antigenicity • Lubricant and protective agent in the gastrointestinal and urogenital tracts

Glycoproteins

mono or disaccharides (sugars) - sweet

Simple carbs

polysaccharides – not sweet

Complex carbs

naturally present in whole foods such as milk and fruit; accompanied by nutrients

Natural suga

separated from its plant source (usually beet, cane); considered as empty calories

Refined sugar