Chapter 8 Carbohydrates Flashcards by Meagan Davis

What are the function of carbohydrates (saccharides)

provide energy
supply carbon for the synthesis of cell components
serve as a form of stored chemical energy
form part of the structures of some cells and tissues
C is the site of synthesis of cell components

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What are the different classes of carbohydrates?

Monosaccharide-glucose, fructose

Disaccharide-sucrose (3)

Oligosaccharide- raffinose

Polysaccharide-starch, cellulose, glycogen

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What are the most simplest carbohydrates?

Monosaccharides

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What are monosaccharides?

Monosaccharides are aldehydes or ketones that contain two or more alcohol groups.

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What are the smallest monosaccharides composed of?

3 carbons

1) Dihydroxyacetone
2) D-Glyceraldehyde
3) L-Glyceraldehyde

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What is an isomer?

Have same molecular formula but different structures

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What is a constitutional isomer?

They differ in the order of arrangement of atoms

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What are stereoisomers?

Atoms connected in the same order but have different spacial arrangment

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What are enantiomers?

Non superimposable images

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What are diastereoisomers?

isomers that are NOT mirror images

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What are Epimers?

Different at one of several asymmetric C atoms

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What are Anomers?

Isomers that differ at a new asymmetric C atom formed on a ring closure

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What is an aldose?

sugar with aldehyde group

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What is a ketose?

sugar with ketone group

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What does triose mean?

3 Carbons

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What does tetrose mean?

4 carbons

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What does pentose mean?

5 carbons

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What does hexose mean?

6 carbons

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What are the monosaccharides you have to know? (7)

Aldotriose—D-Glyceraldehyde
Aldopentoses—D-Ribose
Aldohexoses—
D-Glucose—(EPIMERS OF EACH OTHER)– D-Mannose and finally D-Galactose

Ketotriose—Dihydroxyacetone
Ketohexoses—D-Fructose

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Pentoses and hexoses of aldoses and ketoses form what two ring structures?

Hemiacetal and Hemiketal
–The chemical basis for ring formation is that an aldehyde can react with an alcohol to form a hemiacetal, while a ketone can react with an alcohol to form a hemiketal.

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In the case of glucose, the resulting intramolecular hemiacetal, a six- carbon ring, is called a _____ because of its resemblance to ______.

pyranose and pyran

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In the case of the ketose fructose, the intramolecular hemiketal, a five-carbon ring, is called a _____ because of its resemblance to ____.

furanose and furan

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What is the most stable monosaccharide?

pyranose because they exist in 6 C rings rather than 5 C rings

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If you have a sugar in a beaker and the solution is BLUE. You add Cu to the mixture and the solution becomes dark grey. This means the sugar is ______, which means it has a(n) ________ group.

reducing, aldehyde

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________ can be modified and attached to proteins

simple sugars

What are disaccharides?

the linkage of two sugars

For maltose, a disaccharide, what is the linkage that attaches the two glucose molecules?

O-glycosidic bond

What is the function of glycosyltransferases?

an enzyme that catalyzes the formation of glycosidic bonds.

The monosaccharide substrates for glycosyltransferases are activated by attachment to _______?

uridine diphosphate (UDP)

UDP +glucose + HX ---> sugar + glucose & UDP

General form of a glycosyltransferase reaction

What are the three common disaccharides?

1) Sucrose 2) Lactose 3) Maltose

What are the two functions of a polysaccharide?

storage and structure

What are the two forms of storage in a polysaccharide?

glucose and starch (amylose, amylopectin)

What are polyaccharides?

more than 10 sugar groups linked together

What are the two storage forms of glucose?

glycogen and starch

The polyaccharide ____ is the storage form of _____ in animals

glycogen, glucose

Most glucose units in glycogen are lined by _______, with branches formed by _________ bonds every _____ glucose units.

α-1, 4-glycosidic bonds α-1, 6-glycosidic bonds 10

In plants, glucose is stored as starch of which there are two forms, what are these two forms?

amylose and amylopectin

Amylose is what kind of polymer? How are the glucose units linked? Is there branching?

Amylose is a linear polymer of glucose units linked by α-1, 4-glycosidic bonds with NO branching, all alpha 1-4

Amylopectin is what kind of polymer? How are the glucose units linked? Is there branching?

Amylopectin is a branched polymer, with an α-1, 6-glycosidic bond for every 30 α-1, 4-glycosidic bonds.

_________, a structural component of plants, is made of chains of glucose

Cellulose

Cellulose is what kind of polymer and what are the glucose units linked by?

Cellulose is a homopolymer of glucose units linked by β-1, 4-glycosidic bond.

What does the beta linkage in cellulose make it capable of doing?

The β linkage yields a straight chain capable of interacting with other cellulose molecules to from strong fibrils. It is also optimal for high tensile strenghth

What do the alpha linkages of starch in glycogen make it capable of doing?

The α linkages of starch and glycogen form compact hollow cylinders suitable for accessible storage of sugar.

Describe the kind of polymer Cellulose is for example are the chains branched or unbranched? What are the chains made of? And what are these chains connected by?

Cellulose is a polymer consisting of long, unbranched chains of D-glucose connected by β-1,4 glycosidic linkages

Proteins with carbohydrates attached are called ________. | How many classes are there?

glycoproteins and 3

What are the 3 classes of glycoproteins?

1) Glycoproteins 2) Proteoglycans 3 ) Mucins or mucoproteins diff sugar groups attached to them

What kind of proteins have specific amino acids with sugar linkages attached?

GLYCOPROTEIN

Post-translational modification= what?

GLYCOSYLATION

What is the largest component by weight of the glycoproteins?

Protien

Similar to ser is an amino acid that can bind to sugars. Which is it?

Threonine (thr)

Where can the sugar groups attach to the proteins? (hint: two different kind of linkages)

They can attach to (+) ASN or LYS which attach by the N linkage They can also attach to the neutral (OH) amino acids SER and THR by an O linkage

______ is a glycoprotein that is secreted by the kidney into the blood that stimulates the production of red blood cells.

Erythropoietin

What are proteoglycans?

Proteoglycans are key components of the extracellular matrix and serve as lubricants.

What are proteoglycans attached to?

glycosaminoglycans (GAGs)---SUGARS which make up 95% of the weight (carbohydrate outweighs the protein)

Glycosaminoglycans are composed of repeating units of a _________, one of which is a derivative of an amino sugar and one of which carries a negative charge, either as a ______ or _____.

disaccharide | carboxylate or sulfate

Proteoglycans are important components of what?

Cartilage ---Cartilage is composed of the proteoglycan aggrecan and protein collagen. The glycosaminoglycan component of aggrecan cushions joints by releasing water on impact, and then rebinding water.

Glycosylation on _______ acts to communicate the information to other cells-result in metastasis

Mucin1

Where are mucins commonly found?

mucous secretions

What are mucins over expressed in?

tumors

The more stable a mucin, the more ________ it can be

metastatic

Blood groups are differentiated by _____?

Glycosylation | ex: A, B, and O oligosaccharide antigens

What is the structure of a peptidoglycan?

a) repeating disaccharide unit and b) Cross-linking of the peptidoglycan macromolecule

How does penicillin work?

When you add penicillin, the enzyme takes on penicillin, and the cell wall will break down (Penicillin basically inhibits a transpeptidase involved in bacterial cell wall formation)

_______ are a particular class of glycan-binding protein.

Lectins

Lectins on one cell recognizes and binds to _______ on another cell with weak interactions. Such binding facilitates ___________.

carbohydrates | cell-cell interaction

What are lectins?

they are carbohydrate-binding proteins which have sockets in them (like lock and key)

What are selectins?

A class of lectins (specific carbohydrate binding protein). Some selectins will bind immune cells to sites of injury.

What are the two important features of the influenza virus?

hemagluttin---selectin binding protein and sialic acid is recognized by hemagluttin group

Once hemagluttin and sialic acid is attached (in the influenza virus), ________ cuts the bonds b/w the reaction and allows the entry of virus into cell

Neuraminidase

What does tamiflu do in the reaction of the hemagluttin and sialic acid?

It inhibits/blocks Neuraminidase where the virus will just sit there and the NOT allow the entry of the virus into the cell

What can cause tamiflu resistance?

If Neuraminidase starts to change then they will have to completely change tamiflu itself

Chapter 8 Carbohydrates Flashcards

(72 cards)