Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCAT Biochem > Carbs > Flashcards

Carbs Flashcards

1
Q

monosaccharides

A
  • trioses, tetroses, pentoses, and hexoses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

carbs that contain aldehyde group as their most oxidized functional group

A

aldoses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

carbs that contain ketone group as their most oxidized functional group

A

ketoses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what would a 6C sugar with an aldehyde group be called

A

aldohexose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

simplest aldose

A

glyceraldehyde

O=CH
|
HCOH
|
CH2OH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The aldehyde carbon, C1, can participate in…

A
  • glycosidic linkages
  • sugars acting as substituents via this linkage are called glycosyl residues
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

simplest ketose

A

HOCH2C(=O)CH2OH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

carbonyl carbon of ketose

A
  • C2
  • can participate in glycosidic bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

D-fructose

A

know structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

D-glucose

A

know structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

D-galactose

A

know structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

D-mannose

A

know structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

number of stereoisomers w common backbone

A

2^n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

epimers

A
  • special subtype of diastereomers that differ in configuration at exactly one chiral center
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

monosaccharides contain…

A
  • hydroxyl group nucleophile
  • carbonyl group electrophile
  • therefore aldoses can become hemiacetals and ketoses can become hemiketals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

only cyclic molecules stable in solution due to ring strain

A

pyranose (6 membered)
furanose (5 membered)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

mechanism of hemiacetal or hemiketal formation

A

1) nu attack of second to last hydroxyl group upon electrophilic carbonyl carbon
2) anomeric carbon becomes chiral and the oxygen is protonated

alpha and beta anomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Fischer ~> Haworth

A
  • when we convert monosaccharides from straight-chain Fischer projection to Haworth projection, any group on the right in the Fischer projection will point down
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

mutarotation

A

exposing hemiacetal rings to water cause cause cycling between open and closed form

C1-C2 substituents can rotate freely, either alpha or beta anomer can be formed

unequal proportions at equilibrium bc axial position for hydroxyl groups is unfavored and not stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

monosaccharides contain…

A

alcohols and either aldehydes or ketones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

hemiacetal open ring oxidation

A

when hemiacetal rings are open they can be oxidized to form aldonic acids (the CA version)

aldoses are considered reducing agents since they can be oxidized

22
Q

reducing sugar

A

any monosaccharide with a hemiacetal ring

23
Q

hemiacetal closed ring oxidation

A

yields a lactone, a cyclic ester w a carbonyl group persisting on the anomeric carbon

24
Q

which reagents can be used to detect the presence of reducing sugars?

A

Tollen’s reagent and Benedict’s reagent

25
Q

Tollen’s reagent

A

must be freshly prepared

start with AgNO3, which is mixed w NaOH to produce Ag2O

this is dissolved in ammonia to produce [Ag(NH3)2]+ which is the actual Tollen’s reagent

26
Q

Benedict’s reagent

A

aldehyde of aldose sugar is readily oxidized

indicated by red Cu2O precipitate

27
Q

to test specifically for glucose…

A

use glucose oxidase

28
Q

why do ketose sugars produce positive Tollen’s and Benedict’s tests?

A
  • although ketones cannot be oxidized directly to CAs, they can tautomerize to form aldoses under basic conditions via keto-enol shifts
  • while in aldose form they can react w Tollens or Benedict’s reagents to form carboxylic acid
29
Q

alditol

A

aldehyde group of aldol reduced to alcohol

30
Q

deoxy sugar

A

hydrogen that replaces hydroxyl group on the sugar (deoxyribose)

31
Q

phosphorylation of glucose

A

phosphate group is transferred from ATP to glucose

32
Q

esterification of glucose

A

carb reacts w pyridine and (CH3CO)2O at 0°C to form ester

33
Q

glycoside formation

A
  • hemiacetal react w alcohols to form acetals
  • the anomeric hydroxyl group is transformed into an alkoxy group yielding a mixture of alpha and beta-acetals with H2O as an LG
  • the resulting C-O bonds are called glycosidic bonds and the acetals formed are glycosides
  • react sugar w ethanol and HCl to form glycosides and H2O
34
Q

breaking a glycosidic bond…

A

requires hydrolysis

35
Q

disaccharides and polysaccharides forms as a result of…

A

glycosidic bonds between monosaccharides

36
Q

disaccharides

A
  • glycosidic linkage is nonspecific in that the anomeric carbon of a cyclic sugar can react w any hydroxyl group on any other sugar molecule
37
Q

sucrose

A

know structure

38
Q

lactose

A

know structure

39
Q

maltose

A

know structure

40
Q

polysaccharides

A

long monosaccharide chains linked together by glycosidic bonds

41
Q

a polysaccharide composed entirely of one monosaccharide…

A

homopolysaccharide

42
Q

a polymer made up of more than one type of monosaccharide…

A

heteropolysaccharide

43
Q

cellulose, starch, and glycogen…

A
  • all composed of D-glucose
  • differ in configuration about the anomeric carbon and the position of glycosidic bonds
44
Q

cellulose

A
  • main structural component of plants
  • homopolysaccharide of D-glucose
  • linked by B-1,4 glycosidic bonds
  • we do not have cellulase and therefore cannot digest cellulose
  • hence why fruits and veggies are good fiber
45
Q

starches

A
  • polysaccharides more digestible by humans
  • linked a-D-glucose monomers
  • plants predominantly store starch as amylose (a-1,4 glycosidic polymer)
  • amylopectin, begins as a-1,4 glycosidic polymer and has a-1,6 glycosidic bonded branches
46
Q

iodine starch testing

A
  • Iodine fits into the helical structure of amylose to test for starch
47
Q

B-amylase

A
  • cleaves amylose at the nonreducing end of the polymer (end w acetal) to yield maltose
48
Q

a-amylase

A
  • cleaves randomly along the chain to yield shorter polysaccharide chains, maltose, and glucose
49
Q

amylopectin is broken down by…

A
  • debranching enzymes
50
Q

glycogen

A
  • carb storage unit in animals
  • a-1,6 glycosidic bonds (1 for every 10 glucose molecules whereas amylopectin is 1 in every 25)
  • highly branched
  • branching optimizes the energy efficiency of glycogen and makes it more soluble in solution, thereby allowing more glucose to be stored in the body
  • allows enzymes that cleave glucose from glycogen like glycogen phosphorylase to work on many sites within the molecule simultaneously
51
Q

glycogen phosphorylase

A
  • cleave glucose from nonreducing end of glycogen and phosphorylating it, producing G1-P

MCAT Biochem (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions