carbohydrates Flashcards by Maddi Clark

carbohydrate formula

Cx(H2O)y
- at least 1 c=o
- at least 1 oh

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aldose

terminal c=o

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ketose

internal c=o

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glyceraldehyde

triose in glycolysis that results from split of 1,6 fbp

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ribose

5 c sugar
2’ OH

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deoxyribose

missing 2’ OH

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what is derived from gluocse in ppp

ribose

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what isomer do sugars exsist in

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gluocose

hexose, main source of E
- 3’ OH points in opp direction of others

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frucose

ketoaldose
- metabolized by liver
- corn syrup

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galactose

dairy products and beets
- epimer of glucose
- c3 and c4 opposite c2 and c5 groups

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what form do hexoses and pentoses usually take in nature

cyclic (not linear)

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hemiacetal formation

c=o of aldose reacts with OH
aldehyde + ROH –> c bound to oh and OR

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hemiketal formation

ketone (r1, r2) + R3oh –> c bound to r1 r2 r3 and oh

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pryanose

6 member ring

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furanose v

5 member ring

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what are the substituents bound to central carbon in a hemiacetal

OH OR R and H

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substituents of hemiketal

OH OR1 R2 and R1

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anomers

epimer of the hemiacetal/ hemiketal carbon in a cyclic sugar

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alpha anomer

-OH points down

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beta anomer

-OH points up

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an aqeous solution of glucose at equilibrium has what composition of alpha glucose and beta glucose

2/3 beta glucose

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mutarotation

amount of interconversion between alpha and beta anomers

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anomeric carbon

c1, that gains a 4th constituent after cyclicization

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disaccharides

two carbohydrates bound together

bond of sugars

glycosidic bond

where does the glycosidic bond occur

between anomeric carbon of one sugar and OH group of another

what kind of reaction is a glycosidic bond

dehydration synthesis

sucrose

disaccharide of fructose and glucose

lactose

disach of glucose and galactose

maltose

disach of 2 glucose

bond of sucrose

Glu (alpha 1 - beta 2) fru

bond of lactose

Gal (beta 1 - 4) glu

bond of lactose

glu (alpha 1-4 ) glu

starch

polysach of glucose - made of amylose and amylopectin

amylose

subunit of starch LINEAR a(1-4) bond

amylopectin

major subinit of starch branched a (1-4) with alpha (1-6) branches

which is easier to break down? amylose or amylopectin

amylopectin (branching)

glycogen

human glucose storage - glu (a1,4) branch a 1-6

difference between glycogen and amylopectin

glycogen is more branched at every 8-12 residues while amylopectin is around 30 residues

cellulose

plant structure polysac B 1-4 linkages

T/F humans can digest cellulose

false, source of fiber

primary stores of glycogen

liver and muscle cells

major component of bacterial cell wall

peptidoglycan

chitin

polysach of N-acetylglucosamine via B1-4 bonds . component of cytosekeleton

optical rotation of light refers to

d and l orientations

absolute configurations refer to

R and S

enantiomers

rotate plane polarized light in opposite directions

D carbohydrates

have the higher priority group to the right of the carbon

how to decipher D/L orientation of hexose

the lowest / bottom -OH orientation, if it is to the right its D if it is to the left its L

D/L isomers of a carbohydrate relate how

they are enantiomers

epimer

sugars that only differ at one stereocenter

how many possible stereoisomers are there on a hexose

2^4 --> 16 stereoisomers at 4 chiral centers

formula for possible stereoisomers on a carbohydrate

2^( number of stereocenters)

how many enantiomers does an aldohexose have

1 D and 1L

how many epimers does an aldohexose have

4 (# of stereocenters)

how many diasteriomers does an aldohexose have

14 (epimers are diasteriomers) 16-2

confrimationa

interchangable without breaking bonds

pyranose confrimations

chair, boat

furanose confirmations

envelope form

oxidation agens

Ag 2+, Cu2+, Fe 2+

tollen's test

oxidation of aldose is coupled with reduction of Ag+ to Ag which causes ppt of silver

benidicts reagent

oxidation of aldose with Cu 2+ reduction into cuso4 and make red ppt

reducing sugars

reduce the reagents that are used to moniter a reaction

example of reducing sugar

any hemiacetal formed at the anomeric carbon and the linear form can undergo oxidation

when is a disaccharide a reducing sugar

if anomeric carbon is involved in a glycosidic bond it cannot participate in reduction, but when anomeric carbon is free, it can do so

examples of disaccharides that are reducing sugars

maltose and lactose because they have free anomeric carbons

nonreducing sugar vs reducing sugar

reducing sugars have free aldahydes or ketones where nonreducing do not

example of nonreducing sugar

starch

glycogen reducing or non reducing?

many nonreducing ends (where glucose is added) and 1 reducing end