Chpt.10: Carbohydrate structure and function

Define homopolysaccharide. Give an example.

-same polysaccharides Examples: glycogen starch cellulose

D and L group

D= hydroxyl group on Right side L= hydroxyl group on Left side

Structure of disaccharides sucrose

" Sucrose lacks a free aldehyde or ketone group and is thus a nonreducing disaccharide while lactose and maltose are reducing disaccharides" (Shaw PG.69)

Define heteropolysaccharide. Give an example.

-made up of different polysaccharides -ex. Glycosaminoglycans

Heteropolysaccharides

-made up of different polysaccharides -ex. Glycosaminoglycans -unbranched -repeating sulfate disaccharide units, linear -ideal for a lubricating fluid in the joints, major component of synovial fluid

Define proteoglycan. Give an example.

"(AKA mucopolysaccharides) - family of glycoproteins composed of a high molecular weight protein core to which polysaccharide glycosaminoglycan chains are covalently attached -Example?

plant cell starch

- amylose: a storage polysaccharide, not easily digested, from plants with predominantly a-1,4 bonds - amylopectin: readily digested, branches every 25 residues and side chains up to 25 residues

Define glycosaminoglycan. Give an example.

-AKA "mucopolysaccharides" are long unbranched polysaccharides consisting of a repeating disaccharide unit. -ex. Chondroitin 4-sulfate, Dermatan sulfate, heparin, hyaluronate

Distinguish between the structures (and bonds) of glycogen, starch and cellulose.

-Glycogen - is a homopolymer of glucose monomers joined by alpha 1, 4-glycosidic linkages with alpha 1, 6-glycosidic linkages forming branch points every 8 - 10 residues. Starch -Starch is a polysaccharide composed of D-glucose residues connected by alpha 1, 4-glycosidic linkages.Starch occurs as a mixture of linear amylose, composed of thousands of glucose residues linked by alpha 1, 4-glycosidic bonds, and branched, amylopectin. Cellulose -Cellulose is a long unbranched structural polysaccharide. Cellulose is composed of up to 15,000 D-glucose monomers linked by beta 1,4-glycosidic bonds.. The linear structure of cellulose is stabilized by hydrogen bonds. Humans lack a beta 1, 4- glycosidase (cellulase) enzyme and are therefore unable to digest cellulose.

Glycoprotein

-Protein covalently liked to carbohydrate chain. -found in cellular secretions, they are soluble -proteins that are destined for export -communicate between cells -maintain cell structure -self-recognition by the immune system -coagulation -mucins

Define glycoprotein. Give an example.

-Proteins found covalently attached to a variable carbohydrate oligosaccharide chain -found in cellular secretions, they are soluble -proteins that are destined for export -communicate between cells ex. Erythropoietin, prothrombin, thrombin, and fibrinogen

Glycosaminoglycans are made up of two parts:

-Uronic acid, i.e glucuronate or iduronate -two modified amino sugars: N-acetylgalactosamine and N-acetylglucosamine

Lactose

-disaccharide -found in the milk of mammals -made up of galactose and glucose -hydrolyzed/broken down by lactase- which is absent in lactose intolerant

Maltose

-disaccharide -made of two D-glucose residues -bound together by alpha-1,4-glycosidic link

Structure of maltose

-disaccharide -made of two D-glucose residues -bound together by alpha-1,4-glycosidic link

Structure of lactose

-disaccharide -made up of galactose and glucose -hydrolyzed/broken down by lactase- which is absent in lactose intolerant

Sucrose

-disaccharide -table sugar -made of glucose and fructose linked by (1,2)-glycosidic bond -sucrose to glucose and fructose catalyzed by sucrase

Mucopolysaccarides

-family of glycoproteins under proteoglycans -made up of a protein where an glycosaminoglycan is added to a protein

Distinguish between glycoproteins and glycolipids

-glycoproteins are carbohydrate-protein combinations. -glycolipids are carbohydrate-lipid combinations.

Dermatan sulfate

-glycosaminoglycan -abundant in extracellular matrix of skin and blood vessels -antithrombotic function

Heparin

-glycosaminoglycan -variably sulphated -not found in connective tissue -natural anticoagulant

Glycogen

-how we store excess carbs in liver and muscle -often referred to as animal starch

Describe the structure of polysaccharides

-hundred of monosaccharides linked by glycosidic bond in a condensation reaction

polysaccharides

-hundred of monosaccharides linked by glycosidic bond in a condensation reaction

Carbohydrates exist where in nature?

-plant cellulose -energy stores-glycogen and starch -nucleiv acids -intercellular signaling -attract sperm cells to egg -antigens

Cellulose

-polysaccharide -the most abundant natural polymer in the world -stabilized by interchain and intrachain H-bonds -insoluble in water, not digested by humans

Proteoglycans

-resemble polysaccharides just with more protein -located in ECM (connective tissue) or may be transmembrane proteins -continually turned over by lysosomal enzymes e.g iduronidase -linkage of glycosaminoglycans to protein by specific trisaccharide

homopolysaccharides

-same polysaccharides Examples: glycogen starch cellulose

Describe the structure of monosaccharides.

-simplest end products may be attached to proteins-glycoproteins -at least 3 carbons -at least 2 OH

Monosaccharides

-simplest end products may be attached to proteins-glycoproteins -at least 3 carbons -at least 2 OH -Naming depends on the number of carbons: -triose: 3 carbons -tetroses: 4 carbons -pentoses: 5 carbons -hexoses: 6 carbons -heptoses: 7 carbons

Chrondroitin 4-sulfate

-the most abundant glycosaminoglycans -found in extracellular matrix of connective tissue, cartilage, tendon and bone

Describe the structure of disaccharides

-two monosaccharide's together joined by a glycosidic bond-covalent

Disaccharides

-two monosaccharide's together joined by a glycosidic bond-covalent

"Which one of the following statements about proteoglycans is correct? They"

A. are accurately classified as a subgroup of glycoproteins. B are homopolymers of carbohydrates. C contain a hydroxyproline rich core protein similar to collagen. D. predominate in the intracellular environment."

"Which of the following statements regarding the carbohydrates glycogen and cellulose is incorrect. They differ in:

A. the type of glycosidic bond(s) in the polymer B. their digestibility in humans. C. the fact that glycogen contains more branching than does cellulose. D. their monomeric components."

Review the major functions of carbohydrates.

Carbohydrates are important for : -intercellular communication -maintaining cell structure -key components of the extracellular matrix -work effectively as lubricants and shock absorbers -have been implicated in clot dissolution."

Which highly-sulfated glycosaminoglycan is widely used as an injectable coagulant?

Heparin

Glycosaminoglycans exception

Hyaluronic acid is unique since it is not sulfated and not attached to protein. -found in umbilical chord, synovial fluid, and vitreous humor of the eye.

Define the term ketose and aldose.

Ketose: sugar with ketone functional group I.E D-fructose Aldose: sugar with aldehyde functional group I.E D-glucose

Most carbohydrates exists in the form of?

Polysaccharides

glyconjugates

glycolipids/glycoproteins

Accumulation of the mucopolysaccharide heparin sulfate causing hepatosplenomegaly is characteristric of?

hurler syndrome

Simple molecules

hydrates of carbon

Mucopolysaccharidoses are a family of metabolic disorders caused by the absence of?

lysosome enzymes

Hurlers syndrome

mucopolysaccharides accumulate -iduronidase is not working -aka "lysosomal storage disease"

L- Glyceraldehyde

simplest carbohydrate -monosaccharide -OH group on the left

D-Glyceraldehyde

simplest carbohydrate -monosaccharide -OH group on the right

Aldoses

sugar with aldehyde functional group -D-glucose

Ketoses

sugar with ketone functional group D-fructose

Classification of carbohydrates

°Simple molecules °monosaccharides °disaccharides °oligosaccharides °polysaccharides