BICH 410: Carbohydrates and Lipids

Sivaram 2025

Carbs can be divided into _ and _ isomers

D and L

Epimers are:

a type of diastereomer that differ at only one specific carbon atom. They are a subtype of stereoisomers related to carbohydrates.

Cyclization occurs when

A linear sugar molecule forms a ring structure. -OH of C5 attacks the aldehyde or ketone group at carbon 1 to form a hemiacetal or carbon 2 to form a hemiketal.

Carbohydrates can go through _____ reactions

• Oxidation

• Reduction

• Esterification

• Amination

• Cyclization

Polysaccharides

Multiple monosaccharides linked together by glycosidic bonds.

Lactose’s Glycosidic Linkage:

• B(1—>4)

• Reducing sugar

• Bond between Galactose and Glucose

Lactase

• Enzyme that breaks up the B(1—>4) glycosidic bond

• Hydrolase that catalyzes the hydrolysis of lactose into glucose and galactose.

Sucrose’s Glycosidic Linkage:

• a(1—>2)

• Non-reducing sugar

• Bond between Glucose and Fructose

Homopolysaccharides:

Polysaccharides made up of only one type of monosaccharide unit.

Heteropolysaccharides:

Polysaccharides composed of two or more different types of monosaccharide units.

Cellulose’s Linkage:

• b(1—>4) glycosidic bonds

• Homopolysaccharide (Composed of glucose units)

Cellulase

An enzyme that breaks down cellulose into glucose units by hydrolyzing the beta(1—>4) glycosidic bonds.

Chitin’s Linkage:

• B(1—>4)

• Homopolysaccharide composed of N-acetylglucosamine units.

Starch’s Linkage:

• a(1—>4) mainly and can form a(1—>6) glycosidic bonds

• Homopolysaccharide composed of glucose units.

• 3D, which stores glucose efficiently

Glycogen Linkage:

• a(1—>4) and a(1—>6) linkage

• Present in animal cells for energy storage.

a-amylose’s Linkage:

• a(1—>4) linkage

• Homopolysaccharide composed of glucose units, a component of starch.

Amylopectin Linkage:

• a(1—>4) and a(1—>6) linkageIt differs from amylose due to its branched structure, which allows for more efficient glucose storage.

• A branched homopolysaccharide made of glucose units, also a component of starch.

How is starch broken down?

• Amylase hydrolyzes the a(1—>4) glycosidic bond

• a-glucosidase hydrolyzes on glucose residue at time

• Debranching enzyme hydrolyzes both a(1—>4) and a(1—>6) glycosidic bonds

Glycogen Breakdown:

• Glycogen phosphorylase breaks down the a(1—>4) glycosidic bonds from NON-REDUCING ENDS

• Glycogen debranching enzyme will cleave a(1—>6) bonds

Glycosaminoglycans

• Important components of connective tissue and synovial fluid

• Component of cell surface structure and extracellular substance in blood vessel walls and brain

  • Wound healing

  • Development

Examples of Glycosaminoglycans

• Heparin, Hyaluronate, Chondroitin sulfate, and Keratan sulfate

Joint Supplements

• Glucosamine and chondroitin are part of normal cartilage

• Cartilage acts as a cushion between bones in a joint

Dasuquin:

Two drugs that work together to cause a great effect for joint health and mobility by combining glucosamine hydrochloride and low MW chondroitin sulfate.

Glycoproteins:

• Proteins with carbohydrate components

• Can be O-glycosidic or N-glycosidic bonds

Fatty Acids:

• Simple fats

• Made up of a carboxylic acid and long hydrocarbon tail

• Amphipathic

• Structurally ordered aggregates

Saturated Chains:

• Can pack tightly together and form rigid, organized aggregates

Unsaturated Chains:

• Bend (because of double bonds) and pack in a less ordered way

• Misshaped, forming kinks and changes in shape

• Flexible

• Cis configuration

Stearic Acid

• Saturated

• 18 hydrocarbon chain

Oleic Acid:

• Unsaturated

• 18 hydrocarbon chain with 1 double bond at carbon 9

Linoleic Acid:

• Unsaturated

• 18 carbon chain with 2 double bonds at carbons 9 and 12

a-Linolenic Acid:

• Unsaturated

• 18 carbon chain with 3 double bonds at carbon’s 9, 12, and 15

Why are trans-fats bad?

• Trans fats are bad because these fats will get stuck in adipose fat tissues and can lead to higher levels of LDL cholesterol, increasing the risk of heart disease and stroke.

• We don’t have the machinery to break it down

Palmitic Acid:

• Saturated

• 16 carbon chain with no double bonds

Myristic Acid:

• Saturated

• 14 carbon chain with 0 double bonds

Melting Point Rules:

• More carbons = Higher the melting temp

• More double bonds = Lower the melting temp

Triacylglycerols

• Nonpolar

• Water insoluble

• Glycerol backbone with three fatty acid chains.

• Energy reservoirs

Phospholipids —> Glycerophospholipids

• Amphiphilic

• Can contain a head group after phosphate

• Major component of biological membranes

Phospholipids —> Sphingolipids

• Composed of a sphingosine backbone with one fatty acid and a phosphate and a choline head group