Carbohydrates

Question 1

aldoses

Answer 1

carbohydrates that contain an aldehyde group

Question 2

ketoses

Answer 2

carbohydrates that have a ketone group as their most oxidized functional group

Question 3

Glycosidic linkages

Answer 3

sugars acting as substituents via this linkage are called glycosyl residues

Question 4

Common names of monosaccharides

Answer 4

D- fructose, D-glucose, D-galactose, D-mannose

D-fructose is a ketose, rest are aldose

Question 5

optical isomers/steroisomers

Answer 5

compounds that have the same chemical formula, differ in the spatial arrangement of their component atoms

Question 6

Enantiomers

Answer 6

nonidentical, superimposable mirror images of each other (L glucose and D glucose)

Question 7

Where is the OH in a D sugar?

Answer 7

On the right. “all D-sugars have the hydroxide of their highest number chiral center on the right”

Question 8

Where is the OH in a L sugar?

Answer 8

On the left “all L sugars have the hydroxide of their highest number chiral center on the left”

Question 9

What is the difference in an L and D glucose?

Answer 9

Every chiral center in the D-glucose has the opposite configuration of the L glucose

Question 10

Diasteromers

Answer 10

two sugars that are in the same family, but are not identical and are not mirror images of each other

Question 11

A diastereomer that differs in exactly one chiral center?

Answer 11

epimers

Question 12

What is the most common electrophile on the MCAT?

Answer 12

A carbonyl group

Question 13

What are cyclic hemiacetals formed from?

Answer 13

Aldoses

Question 14

What are cyclic hemiketals formed form?

Answer 14

Ketoses

Question 15

Pyranose?

Answer 15

Six member ring/saccharide with 5 carbons and one oxygen

Question 16

Furanose?

Answer 16

5 member ring/saccharide

Question 17

Anomeric carbon

Answer 17

The carbonyl carbon becomes chiral, will form an alpha or beta anomer

Question 18

alpha-anomer

Answer 18

the OH group of C-1 is trans to the CH2OH substituent (A town down), axial and down

Question 19

beta-anomer

Answer 19

the OH group of C-1 is cis to the -CH2OH substituent (equatorial and up)

Question 20

mutarotation

Answer 20

exposing hemiacetal rings to water will cause them to spontaneously cycle between the open and closed form, making alpha and beta anomers

Question 21

Aldonic acids

Answer 21

oxidized aldoses, aldehydes are oxidized to form catalytic acids

Question 22

Any monosaccharide with a hemiacetal ring is considered?

Answer 22

a reducing sugar

Question 23

When an aldose in a ring form is oxidized it yields a…?

Answer 23

Lactone–> a cyclic ester with a carbonyl group persisting on the anomeric carbon

ex. vitamin C

Question 24

Tollens’ reagent

Answer 24

Helps detect a reducing sugar, AgNO3 is mixed with NaOH to produce a silver oxide (Ag2O), dissolved in ammonia to produce [Ag(NH3)2]+, the actual Tollens’ reagent

Question 25

Benedict’s reagent?

Answer 25

The aldehyde group of an aldose is readily oxidized, indicated by a red precipitate of Cu2O.

(so benedict’s reagent is basically Cu++. It tests for reducing sugars, so sugars that can reduce Cu++ to Cu+. That means that the sugar becomes oxidized. Glucose is an aldehyde, so oxidizing the aldehyde gives you a carboxylic acid, or a carboxylate.)

Question 26

Tautomerization

Answer 26

refers to the arrangement of of bonds in a compound, usually by moving a hydrogen and forming a double bond

ketone–> enol (OH with a double bond)

Question 27

enol

Answer 27

a compound with a double bond and an alcohol group

Question 28

alditol

Answer 28

when the aldehyde group of an aldose is reduced to an alcohol, the compound is considered an alditol

Question 29

Deoxy sugar

Answer 29

contains a hydrogen that replaces a hydroxyl group on the sugar

Question 30

Hemiacetals react with alcohols to form…?

Answer 30

acetals

will form glycosidic bonds and the acetals formed are glycosides

Question 31

Glycosides derived from furanose rings are referred to as…?

Answer 31

furanosides

Question 32

Glycosides derived from pyranose rings are called…?

Answer 32

Pyranosides

Question 33

Sucrose

Answer 33

glucose - alpha 1,2 fructose

G-F

Question 34

Lactose

Answer 34

galactose- beta- 1,4 glucose

Question 35

Maltose

Answer 35

glucose- alpha- 1,4- glucose

Question 36

Cellobiose

Answer 36

glucose- beta- 1,4 glucose

Question 37

A polysaccharide composed entirely of glucose?

Answer 37

Homopolysaccharide

Question 38

A polymer made up of more than one type of monosaccharide…?

Answer 38

Heteropolysaccharide

Question 39

Celluose

Answer 39

main structural component of plants, homopolysaccharide, chain of B-D-glucose molecules linked by B-1,4 glycosidic bonds

Question 40

Starches

Answer 40

polysaccharides that are more digestible by humans, linked alpha-D-glucose monomers, predominantly store starch as amylose; amylopectin is also a starch

Question 41

Amylose

Answer 41

linear glucose polymer linked by alpha- 1,4 glycosidic bonds, how plants store starch

degraded by beta-amylase (cleaves off non-reducing end) while alpha-amylase cleaves randomly along the chain to yield shorter polysaccharide chains, maltose, and glucose

Question 42

Amylopectin

Answer 42

has alpha- 1,4 glycosidic bonds, but also has alpha 1,6 glycosidic bonds

Question 43

Glycogen

Answer 43

carbohydrate storage unit in animals, like starch but with more alpha-1,6 glycosidic bonds, highly branched

can be cleaved with glycogen phosphorylase

Question 44

Glycogen phosphorylase

Answer 44

functions by cleaving glucose from the non-reducing end of a glycogen branch and phosphorylating it, thereby producing glucose-1-phosphate which plays an important role in metabolism

Question 45

Phosphorylation

Answer 45

when a phosphate ester is formed by transferring a phosphate group from ATP onto a sugar