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2. wk > Carbohydrates Struc and Functions > Flashcards

Carbohydrates Struc and Functions Flashcards

1
Q

How are Carbohydrates formed?

A

-Produced from CO2 and H2O via photosynthesis in plants

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2
Q

Name some functions which carbohydrate

A
  • energy source and energy storage
  • structural component of cell walls and exoskeletons
  • informational molecules in cell-cell signaling
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3
Q

If carbohydrates are linked with protein what do we get?

A

-Can be covalently linked with proteins to form:

glycoproteins and proteoglycans

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4
Q 
structure:
What are alkyl halide?
What are amine?
What are ether?
What are aldehyde?

What are amide?

A
  • CX (X= F,Cl, Br, I)
  • CNH2
  • COC
  • COH (double to O, H connected to C)
  • CONH2 (double to O, NH2 connected to C)
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5
Q

What does R and S characterize in Cahn-Ingold-Prelog Convention?

A

-R and S characterize the absolute configuration characterize the absolute configuration of a specific stereocenter, not a whole molecule
-R - rectus - right
S - sinister - left
-have to draw a cercial from the most priority (atom mass) to lowest
->Only the chiral carbon (is a carbon atom that is attached to four different types of atoms or groups of atoms) that is most distant from the carbonyl carbon is designated as D (right) or L (left)

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6
Q

Which functional group does aldose contain? Which functional group does ketone contain?

A
  • An aldose contains an aldehyde functionality
    (s. a. Glyceraldehyde (aldotriose))
  • A ketose contains a ketone functionality
    (s. a. Dihydroxyacetone (ketotriose))
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7
Q

What are enantiomers?

A

-Stereoisomers that are non-superimposable mirror images
(nicht übereinander spiegelbar)
-s.a. D and L isomers of a sugar are enantiomers
For example, L and D glucose have the same water solubility

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8
Q

Are most hexoses and simple sugars L or D form?

A
  • Most hexoses in living organisms are D stereoisomers

- Some simple sugars occur in the L-form, such as L-arabinose

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9
Q

What do horizontal bonds show in Fischer projections?

A
  • Horizontal bonds are pointing toward you

- vertical bonds are projecting away from you

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10
Q

What are diastereomers?

A
  • stereoisomers that are not mirror images

- >have different physical properties

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11
Q

What are epimers?

A

-Epimers are two sugars that differ only in the configuration around one carbon atom

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12
Q

Which structure are to know?

A
  • Ribose is the standard five-carbon sugar
  • Glucose is the standard six-carbon sugar
  • Galactose is an epimer of glucose (epimer at C-4)
  • Mannose is an epimer of glucose (epimer at C-2)
  • Fructose is the ketose form of glucose
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13
Q

What are hemiacetals and hemiketals?

A
  • Aldehyde and ketone carbons are electrophilic
  • Alcohol oxygen atom is nucleophilic
  • When aldehydes are attacked by alcohols, hemiacetals form
  • When ketones are attacked by alcohols, hemiketals form
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14
Q

Pentoses and hexoses undergo which process? Describe the process

A
  • they readily undergo intramolecular cyclization
  • The former carbonyl carbon becomes a new chiral center, called the anomeric carbon
  • The former carbonyl oxygen becomes a hydroxyl group
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15
Q

How is the anomer determined to be alpha or better?

A
  • If the hydroxyl group is on the opposite side (trans) of the ring as the CH2OH moiety the configuration is α
  • If the hydroxyl group is on the same side (cis) of the ring as the CH2OH moiety, the configuration is β
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16
Q

What are pyranoses, furanoses? What is an anomeric carbon; where is it drawn?

A
  • Six-membered oxygen-containing rings are called pyranoses
  • Five-membered oxygen-containing rings are called furanoses (4erC, ein O im Ring)
  • anome ist ein Chiralitätszentrum ,The anomeric carbon is usually drawn on the right side
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17
Q

How does the chain-ring equilibrium look like?

A

-ring form on one side and open chain form (linear) on the other side

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18
Q

Which tests can help with the detection of reducing sugar?

A
  • Aldehyde can reduce Cu^2+ to Cu^1 (Fehling’s test)

- Aldehyde can reduce Ag^1 to Ag^0 (Tollens’ test)

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19
Q

How does the colorimetric glucose analysis work?

A
  • enzymatic methods are used to quantify reducing sugars such as glucose
  • The enzyme glucose oxidase catalyzes the conversion of glucose to glucono-δ-lactone and hydrogen peroxide (H2O2)
  • Hydrogen peroxide oxidizes organic molecules into highly colored compounds
  • Concentrations of such compounds is measured colorimetricall
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20
Q

Where is the colorimetric glucose analysis used?

A

-Electrochemical detection is used in portable glucose sensors

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21
Q

Name important Hexose Derivates

A
  • go to:

https: //www.purposegames.com/game/7c290dda7d

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22
Q

Give the abbreviations for :
Abequose, arabinose, fructose, fructose, galactose, glucose, mannose, rhamnose, ribose, xylose, glucuronic acid, galactosamine, glucosamine, N-acetylgalactosamine, n-acetylglucosamine, iduronic acid, muramic acid, N-acatylmuramic acid, N-acetylneuraminic acid

A

-abe, ara, fru, fuc, gal, glc, man, rha, rib, xyl, GlcA, GalN, GlcN, GalNAc, GlcNAc, IdoA, mur, Mur2Ac, Neu5Ac

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23
Q

How is an acetal produced?

A
  • reaction of a hemiacetal with an alcohol in acidic solution
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24
Q

Between which two carbons can a glycosidic bond occur?

A
  • Two sugar molecules can be joined via a glycosidic bond between an anomeric carbon and a hydroxyl carbon
  • bewteen two anomeric carbons
25
Which is less reactive: | -glycosidic bond (an acetal) between monomers or the hemiacetal at the second monomer?
- glycosidic bond (an acetal) is less reactive - >Second monomer, with the hemiacetal, is reducing - >Anomeric carbon involved in the glycosidic linkage is nonreducing
26
What is maltose?
-The disaccharide formed upon condensation of two glucose molecules via 1 → 4 bond is called maltose
27
What does the product of two anomeric carbons joined together with a glycosidic bond have?
- The product has two acetal groups and no hemiacetals | - >There are no reducing ends, this is a nonreducing sugar
28
How is Lactose created? How is Sucrose created? How is Trehalose created?
Lactose: -b-d-galactopyranosyl (1->4)-b-d-glucopyranose Sucrose: -b-d-fructofucanosyl (1->2) a-d- glucopyranoside -a-d-glucopyranosyl (1->1) a-d-glucopyranoside
29
How are natural carbohydrates usually found?
-found as polymers
30
What can these polysaccharide (polymers) be?
- homopolysaccharides - heteropolysaccharides - linear - branched
31
What do polysaccharide not have? (in contrast to proteins)
- Polysaccharides do not have a defined molecular weight | - >no template (Vorlage) is used to make polysaccharides
32
Difference between heteropolysaccarides and homopolysaccharides?
-heteropolysaccharides consist of two or more monomer types homo does not
33
What is glycogen?
- is a branched homopolysaccharide of glucose - >storage (polysaccaride) form of glucose (for animals) (needed for transport to cells) - >weight reaches several millions
34
Where are linked chains + branching points in glucose?
- Glucose monomers form (α1 → 4) linked chains | - Branch-points with (α1 → 6) linkers every 8–12 residues
35
What is starch (Stärke)?
-s a mixture of two homopolysaccharides of glucose
36
Which two types of starch exists in plants?
- Amylose is an unbranched polymer of (α1 → 4) linked residues - Amylopectin is branched like glycogen but the branch-points with (α1 → 6) linkers occur every 24–30 residues - >Molecular weight of amylopectin is up to 200 million - >main storage polysaccharide in plants
37
What do glycogen and starch form in metabolism? What do they contain?
- often form granules in cells - Granules contain enzymes that synthesize and degrade these polymers - Glycogen and amylopectin have one reducing end but many nonreducing ends - Enzymatic processing occurs simultaneously in many nonreducing ends
38
What is cellulose?
- Cellulose is a branched homopolysaccharide of glucose - Glucose monomers form (β1 → 4) linked chains - >linear structure (unlike starch and glycogen)
39
Which bond occurs in cellulose and what is the result?
- Hydrogen bonds form between adjacent monomers - Additional H-bonds between chains - Structure is now tough and water-insoluble (wasserunlöslich)
40
What is the difficulty with the cellulose metabolism?
- The fibrous structure and water-insolubility make cellulose a difficult substrate to act on - >Most animals cannot use cellulose as a fuel source because they lack the enzyme to hydrolyze (wasserspaltung) (β1 →4) linkages
41
Which role does cellulase take if it comes to ruminants, fungi, bacteria?
- Fungi, bacteria, and protozoa secrete (ausscheiden) cellulase, which allows them to use wood as source of glucose - Ruminants and termites live symbiotically with microorganisms that produces cellulase
42
What is the structure of Chitin made of?
- is a linear homopolysaccharide of N-acetylglucosamine | - N-acetylglucosamine monomers form (β1 → 4)-linked chains
43
Describe the properties of Chitin
- Forms extended fibers (Fasern) that are similar to those of cellulose - Hard, insoluble, cannot be digested (verdaut) by vertebrates (Wirbeltire) - Structure is tough but flexible, and water-insoluble
44
Where is Chitin found?
-Found in cell walls in mushrooms, and in exoskeletons of insects, spiders, crabs, and other arthropods
45
What is glycosaminoglycans made of? What can one monomer be?
-is a Linear polymers of repeating disaccharide units -monomer: -N-acetyl-glucosamine or -N-acetyl-galactosamine are also modified to contain negatively charged groups: -Uronic acids (C6 oxidation) -Sulfate esters
46
What do glycosaminoglycans form with fibrous (faserig) proteins?
- form extracellular matrix - >connective tissue (Gewebe) - >Lubrication of joints (Gelenke)
47
Name types of glycosaminoglycan
-Hyaluronate (50000 disaccharides) (GlcA- (B1-3) GlcNAc (B1-4) -Chondroitin 4-sulfate (20-60) (GlcA (B1-3) GalNac4S (B1-4) -Keratan sulfate (25) (Gal (B1-4) -GlcNAc6S) (B1-3) -Heparin (15) IdoA2S (a1-4) GlcNS3S6S (a1-4)
48
Name the roles of starch, glycogen, cellulose, chitin, dextran, peptidoglycan, agarose, hyaluronan (a glycosaminoglycan)
- starch-> energy storage in plants - glycogen: energy storage in bacteria and animal cells - cellulose: in plants gives rigidity (steifheit) and strength to cells - chitin: in insects, spiders, gives rigidity and strength to exoskeletons - dextran: in bacteria, gives rigidity and strength to cell envelope - agarose: in algae, cell wall material - hyaluronan: in vertebrates, extracellular matrix of skin and connective tissue; viscosity and lubrication in joints
49
What is glycoprotein?
- a protein with small oligosaccharides (small number of sugar) attached - >carbohydrate attached via it anomeric carbon on protein
50
Where do carbohydrates play a role in? (reco)
-protein- protein recognition
51
With what do viral proteins heavily glycosylated help?
-evade (umgehen) the immune system
52
Which two types of linkages exist in Glycoprotein?
oligosaccharides might be attached to protein -O linkage: via the oxygen atom on the side chain of threonine or serine -N linkage: via nitrogen atom (NH) on the side chain of asparagin
53
How is proteoglycan constructed?
-Sulfated glucoseaminoglycans attached to a large rod-shaped protein in cell membrane
54
What are syndecans, and glypicans?
- Syndecans: protein has a single transmembrane domain | - Glypicans: protein is anchored (verankert) to a lipid membrane
55
What is the function of articular cartilage (Gelenkknorpel) within a joint?
- reduce friction | - load balancing (Lastverteilung)
56
What is extracellular matrix (ecm) ? The role? Main components
-Material outside the cell -Strength, elasticity, and physical barrier in tissues -Main components: Proteoglycan aggregates Collagen fibers Elastin (a fibrous (faserig) protein)
57
What are some integral membrane proteins?
- some are proteoglycans - > syndecans - other are receptors for extracellular proteoglycans - >integrins
58
What do the proteins regulate by transmitting signals into the cell?
- cell growth - cell mobility - apoptosis (genetisch programmierter Zelltod, der für die Entwicklung vielzelliger Organismen notwendig ist) - wound healing

2. wk (9 decks)

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