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Flashcards in Carbohydrates Deck (61):
1

What is a carbohydrate

a polyhydroxy aldehyde or ketone or a derivative thereof: usually cyclized, usually have the formula CH2O, some contain nitrogen, phosphorus or sulfur

2

What are glyconjugates

Carbohydrate polymer attached to protein (glycoprotein) or lipid (glycolipid)

3

What are the three classes of carbohydrates

1. monosaccharides
2. Oligosaccharides
3. polysaccharides (glycogen and starch)

4

What are monosaccharides

Simple sugars; a single polyhydroxy aldehyde or ketone unit

5

What is the most common monosaccharide found in nature

D-glucose (dextrose)

6

What are oligosaccharides

short chains of monosaccharides linked by glycosidic bonds. Most abundant are the DISACCHARIDES - have a name ending in -ose

7

What are polysaccharides

Longer chains (more than 20 aa) some are linear, some branched. Ex are starch and cellulose

8

Monosaccharides are ___ and ___solids that are freely ____ in water and ___ in nonpolar solvents

colorless; crystalline; soluble; insolule

9

Backbone of monosaccharides are:

an unbranched chain of 3-7 carbons
-all carbons linked by a single bond
-0ne carbonyl group (aldehyde or ketose)

10

what is an aldose

When the carbonyl group is at the end of the carbon chain in an aldehyde group - simplest is glyceraldehyde

11

what is a ketose

The carbonyl group is at any other position as a ketone - simplest is dihydroxyacetone

12

What are constitutional isomers

They have same formula but different structure

13

what are stereoisomers

a molecule with chiral centers and can have 2^n stereoisomers

14

What are isomers

compounds that have the same molecular formula

15

What are stereoisomers

They have the same connectivity

16

what is an epimer

Differes only at one C

17

What is an anomer

subgroup of epimers in which Differs at the carbonyl C

18

How are monosaccharides further classified

by the number of carbons. we are focusing on the pentoses (5) and hexoses (6)

19

Glucose is an

aldohexose

20

Fructose is a

ketohexose

21

glucose and fructose have same formula but different connectivity so they are

consitutional isomers

22

mannose glucose and galactose plus fructose are

the most abundant sugars

23

mannose glucose and galactose are

stereoisomers; they have the same connectivity

24

All monosaccharides except ____ have one or more assymetric chiral C atoms

dihydroxyacetone

25

By convention, the OH is drawn to the right for the ___isomer

D

26

Our amino acids are ___

L

27

Optical activity and absolute configuration are ___related

NOT

28

Almost all monosaccharides are in the ___form

D

29

D- ____ is the most abundant monosaccharide in the body

glucose

30

when the carbonyl carbon forms a covalent bond with the oxygen of an OH (alcohol) group along the chain you can form a

Hemiacetal --> acetal
Hemiketal --> Ketal

31

Five membered rings form a

furan --> form of sugar is called furanose

32

6 membered ring forms a

pyran-->pyranose

33

When hydroxyl is below the rings its called

alpha

34

when hydroxyl group is above the ring its called

Beta

35

What does mutarotation refer to

when alpha and beta OH groups move around and rotate

36

The hydroxyl group can usually be replaced by another substituent, usually an ___group

amino

37

____is important in bacterial cell walls

N-acetylmuramic acid

38

Monosaccharides can oxidize carbonyl (aldehyde groups) to COOH which yields ____acid

aldonic; gluconate from glucose

39

If you oxidize the last C in chain you form ____acid

uronic; glucoronate from glucose

40

If you form internal esters you get

lactones

41

What is chlorhexidine

used as achlorhexidine gluconate derivative. A chemical antiseptic for maintaing oral hygience in treatment of gingivitis and periodontal disease

42

What is sialic acid

A derivative of N-acetylmannosamine which is impt for components of many glycoproteins, proteoglycans and glycolipds

43

What are phosphate esters of sugars

very important in metabolism. Traps sugars inside cells and activates OH groups for further reactions

44

What are enediol formations

Important in isomerization of glucose 6-P to fructose 6-P. Reaction is catalyzed by phosphoglucoisomerase

45

What is xylitol

a sugar alcohol which is a pentose derivative which is associated with a reduction in caries incidence

46

What is inositol

sugar molecule that is a important in cell signaling. AKA Vitamin B8 found in kiwi. May be effective in helping spina bifida

47

What are reducing sugars

Mild oxidzing agents like iron and copper will oxidize the sugar that will reduce the metal and cause a color change. These sugars are called reducing sugars

48

What are glycosides

Monosaccharides in solution are hemiacetals which can react with an alcohol to form acetals. Linkage to alcohol is an O-glycosidic bond

49

N -linked bond is when sugars can attach to ___group

amide

50

What are disaccharides

When a monosachharide is joined by another monosaccharide joined by an O -glycosidic bond

51

Which carbons are anomeric?

The carbonyl carbons

52

How do you determine if a sugar is reducing or non reducing

Depends on whether the anomeric carbon is involved in the glycosidic bond. If its free its reducing, if its not, its non reducing

53

Sucrose is a ___ ___ disaccharide

non- reducing

54

What are the most common disaccharides

Maltose = glucose + glucose
Lactose+ glucose + galactose
Sucrose = Glucose + fructose

55

What is lactose

most abundant sugar in milk. poorly absorbed.

56

Small intestine secretes ____ to hydrolyze glucose and galactose

lactase

57

What is lactose intolerance

Lactose not being absorbed. Causes osmotic imbalance. You get diarreah. Bacteria starts to ferment it so you get a lot of gas

58

What are 3 types of lactose intolerance

1. Primary: Due to genetically controlled decline in intestinal lactase. Permanent. give patient a bolus of lactose and monitor for rise in blood glucose levels. If levels go up they are intolerant
2. Secondary: Due to damage to intestine wall (temporary)
3. Congenital: Genetic lack of lactase (rare)

59

What are homopolysaccharides

Serve as storage forms of monosaccharides used as fuels: starch in plants, glycogen in animals

60

What is starch

Main storage polymer of plant cells.

61

What are the two polymers of starch

1. Amylose: Linear homopolymer of D-glucose linked alpha 1-4
2. Amylopectin: branched polymer of D-glucose; branches alpha 1-6