Ch. 11 Carbohydrates: structure and function

Biochemistry And Molecular Biology 404 with Hargrove at Iowa State University

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By: Paul Goldenstein
Created: 2011-10-21
Size: 52 flashcards
Views: 15

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Monosaccharides

D-glyceraldehyde

dihydroxyacetone

glucose

galactose

fructose

ribose and 2'-deoxyribose

Carbohydrate

Hydrates of carbon

Cn(H2O)n

Polyhydroxy - aldehydes or ketones and their derivatives

a.k.a. saccharides

Functions of carbohydrates

Provides energy through glucose metabolism

Structural and protective materials

components of nucleic acids

markers for molecular recognition

Precursors for synthesis of other molecules

Basic Carbohydrate types

Monosaccharides

Disaccharides

-ose

indicates a carbohydrate

Carbohydrate classification

based on the number of carbons in the chain.

simplest carbohydrates

trioses

can be aldose or ketose sugar

Naturally made chiral carbohydrates

D-form

chirality is defined by the

second to bottom carbon

Terminal aldehyde carbon is

Carbon 1

Monosacharides differing at only one chiral center are called

epimers

aldehyde + alcohol =

hemiacetal

ketone + alcohol =

hemiketal

self alcohol attack on the aldehyde group causes

ring structures

six carbon ring sugar

pyranose

forming ring sugars is a

reversible process

mutarotation

switching from alpha to beta forms of glucopyranose

Furanose

5 carbon ring sugar

Ribopyranose

not found very often in the body

B-D-glucopyranose

most stable sugar

Pyranose rings

chair or boat form (chair is more common)

Furanose rings

C-3-endo or C-2-endo

More steric hindrance from

axial groups

Sugar Alcohol rxn

R-CHO ---Reducing agent ---> R-CH2-OH

Glycosidic bond

prevents mutarotation

is at the entomeric carbon

what reduces copper?

free anomeric carbonyl

Reducing sugar

has no glycosidic bond

Glycosidic bond formation

1. Which anomer- alpha or beta

2. what two carbons are on either side of the O-linkage

3. Oligomer can be alpha or beta

Glycosides

linked saccharides

stable compounds (not in equilibrium with open chain)

Disaccharides

Two monosaccharides linked by acetal bond (glycosidic bond)

link between anomeric carbon of one sugar and an OH group of second

water molecule eliminated when formed.

Cellobiose

glucose, glucose (beta 1-4 bond)

Sucrose

glucose, fructose (alpha beta 1-2 bond)

Lactose

galactose, glucose (beta 1-4 bond)

maltose

glucose, glucose (alpha 1-4 bond)

Galactosemia

cannot convert galactose to glucose, caused by mutant gal-1-P uridylyltransferase

causes cataracts and neurological disorders.

Lactose intolerance

lack or insufficient ammout of lactase.

lactase is required to hydrolyze lactose.

If you don't digest it, the bacteria in your gut will, causing intestinal distress.

Cellobiose is

incredibly stable due to hydrogen bonding

sucrose

table sugar

produced by plants

disaccharide of alpha glucose and beta fructose (1-2 bond)

non-reducing sugar

invertase or sucrase hydrolyzes sucrose to form glucose and fructose

Artificial sweeteners

saccharin

aspartame

sucralose

Polysaccharides

polymers of monosaccharides

glycosidic bonds

structural characteristics:

-indentity and order of monosaccharide units

-alpha or beta linkages

-site of linkage

-approx length

-degree of branching

Structural characteristics of Polysaccharides

-indentity and order of monosaccharide units

-alpha or beta linkages

-site of linkage

-approx length

-degree of branching

-can be homo- or heteropolymers

Starch

energy storage used by plants

synthesized and stored in plastids

long repeating chains of alpha-D-glucose (up to 4000 units, alpha 1-4 linkages, alpha 1-6 branch sites)

amylose = straight chain

amylopectin = branched structure

Amylopectin structure

branch points at about every 25-30th amino acid

single reducing end and many non-reducing ends

Glycogen

energy storage in animans

stored in liver and muscles and granules

hydrolysed to maintain blood glucose level

to supply glucose quickly to muscle cells for energy matabolism

Glycogen structure

homopolymer of glucose

similar to amylopectin, just more highly branched, with branch points (alpha 1-6) every 10th amino acid

important in glucose mobilization

Cellulose

possibly the most abundant polysaccharide

in cellophane, rayon, and paper

homopolymers of glucose

animals cannot digest cellulose

wood rot fungi and some bacteria produce cellulase

termites and ruminants contain these microbes

Cellulose structure

beta 1-4 glycosidic linkages

beta configuration allows very long straight chains

results in long fibers - 10,000 to 15,000 amino acids

extensive H-bonding can form extremely strong structures.

Proteoglycans

have important structural and functional roles

have more carbohydrate, less protein

Complex carbohydrates

are synthesized by specific enzymes, glycosyltransferases, from sugar mucleotides

Glycoproteins:

more protein, less carbohydrate

proteins that carry covalently bound carbohydrates

Biological functions of Glycoproteins

immunological protection, host-pathogen interaction

growth inhibition (cell-contact inhibition)

cell-cell recognition, virus recognition

blood clotting, blood antigens

many unknown functions

About this deck

By: Paul Goldenstein
Created: 2011-10-21
Size: 52 flashcards
Views: 15

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
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