Chapter 4: Carbohydrate Structure and Function Flashcards Preview

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Flashcards in Chapter 4: Carbohydrate Structure and Function Deck (50):
1

Aldose

carbohydrate with an aldehyde group as their most oxidized group

2

Hemiketal

Compound formed when an alcohol groups attaches to a ketone. The carbonyl double bond breaks and an alchohol group attaches.

  • The Oxygen loses its double bond, and now recieves the pi electrons and a negative charge
    • It recieves a hydrogen
  • Since the carbon now has four different groups attached, it becomes chiral

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3

Glycogen

What are its properties?

What enzyme is involved with it and what does it do?

  • The carbohydrate glucose storage unit of all animals.
  • It is a highly branched polysaccharide made up of only α-D-glucose molecules
  • Linked together by α-1,4 and α-1,6 glycosidic bonds.
  • Properties
    • High solubility due to branching
    • Ton of storage due to branching
  • It is converted into glucose 1-phosphate by Glycogen Phosphorylase enzyme

    • which cleaves portions of glycogen into glucose and then phosphorylates them

4

Acetal

A compound when two alchohol groups are added to an aldehyde.

  • Causes the carbon=oxygen double bond to break and attach two alcohol (-OR) groups

 

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5

in terms of metabolism, is it better for carbohydrates to be oxidized or reduced? Why?

For metabolism, it is best for carbohydrates to be oxidized so that they reduce other compounds

6

What is more highly branched:

Glycogen or Amylopectin?

What are they made up of and what are their linkages?

  • Both are branched but Glycogen is more branched than Amylopectin
  • Both are made up of α-D-glucose molecules
  • Linked together by α-1,4 and α-1,6 glycosidic bonds.

7

Is the formation of glycosidic bonds a hydrolysis or dehydration reaction?

What about the breaking of a glycosidic bond?

Glycosidic Bond Formation

  • It is a dehydration reaction, because the anomeric hydroxyl recieves another hydrogen and leaves as water.
    • Dehydration reaction because a bond is formed by removing water
  • Then an -OR group is attached to the anomeric carbon

________________________________________Glycosidic Bond Breaking

  • .It is a hydration reaction, because water is brought back onto the anomeric carbon, then the hydrogen leaves to form hydroxyl.

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8

On fischer projects, Horizontal is what? Vertical?

(Wedge/Dash)

What do the intersections represent?

Horizontal is wedge

Vertical is dash

  • Imagine someone putting their arms toward you to hug you (wedge)
  • The intersections represent chiral carbons

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9

Hemiacetal

Compound formed when an alcohol group is added to an aldehyde

  • The carbonyl double bond breaks and attaches the alcohol group to the carbonyl carbon 
    • Makes the carbonyl carbon chiral

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10

Draw the structures of the following 4 important monosaccharides:

D-fructose

D-glucose

D-galactose

D-manose

  • The first five carbons are your fingers
  • ALL have middle finger pointing hydroxyl up
  • D-fructose is the only one with CH2OH on top and a carbonyl on C-2
  • D-glucose has a middle finger pointing up
  • D-galactose has a galactic hand gesture with middle and ring finger up
  • D-mannose is making a peace sign because it’s a hippie saying “peace man”

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11

Which type of another causes steric hinderance and why? 

α-anomers and β-anomers

α-anomers cause steric hindreance betause the hydroxyl group on the anomeric carbon occupies an axial position straight down on the chair.

  • Causes steric hindrance with other molecules in axial.

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12

equation for number of possible stereoisomers

Possible stereoisomers = 2n

  • n: number of chiral centers

13

Cellulose 

structure?

what is it used for?

  • Main structural component of plants. 
  • Humans cannot digest cellulose because we don't have enzymes to break the beta glucose-glucose linkages
  • It is a made up of β-D-glucose molecules only.
  • Connected by β-1,4 glycosidic bonds

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14

Define Furanoside and Pyranoside

  • Furanoside = five membered carb ring attached to another compound by a glycosidic bond.
  • Pyranoside - six membered carb ring attached to another compound by a glycosidic bond.

15

Maltose

Maltose is a dissacharide made up of two D-glucose molecules

  • Connected by an α-1,4 glycosidic bond
  • glucose-glucose

 

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16

Tautomerization.

What happens if a Ketose undergoes tautomerization. What is the product and the intermediate?

  • The rearrangement of bonds in a compound, usually by moving a hydrogen and forming double bonds.
  • When Ketose undergoes tautomerization, it forms an enol intermediate and an aldose product

 

 

 

 

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17

polysaccharides 

long chains of monosaccharides linked together by glycosidic bonds

18

Pyranose.

What is its geometry.

Six membered carbohydrate ring which has a chair conformation.

 

19

Glycosidic Bond Formation of Carbohydrates

 

A bond that forms between an anomeric carbon's hydroxyl group and another compound.

  • Hemiacetal/Hemiketal reacts with alcohols under acidic conditions to form acetals/ketals
  • The hydrogen of the hydroxyl group is replaced by another molecule.

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20

Do diasteriomers have similar or different chemical/physical properties?

Do they have equal but opposite optical activities?

  • They all have different chemical/physical properties
  • Diasteriomers have very different optical activities, not equal but opposite
  • Enantiomers do have equal but opposite optical activities

21

Furanose.

What is its geometry?

five membered carbohydate ring

Planar

22

Define Mutatoration.

What causes it?

Which anomer is most prevalent?

 

When water causes a hemiacetal carbohydrate ring to open and close switching between α-anomers and β-anomers.

  • Creates a mixture of α-anomers and β-anomers
    • β-anomers are most prevalent because they occupy a more stable equatorial position on the chair conformation. 
  • Remember: α-males are not stable and can fuck up someone at any second.

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23

Define Aldonic Acid 

Define Alditol

  • Aldonic Acid = when the aldehyde of a noncyclic aldose carbohydrate becomes oxidized (O added)

 

  • Alditol = when the aldehyde of a noncyclic aldose carbohydrate becomes reduced (O removed)
    • The double bond between oxygen and carbon is turned into a single bond
    • Almost as if double oxygens become one

 

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24

Sucrose

A dissacharide made up of one  D-glucose and one D-fructose molecules

  • Connected by α-1,2 glycosidic bond
  • Glucose-Fructose

 

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25

Glycogen phosphorylase

Enzyme that cleaves the branches of glycogen to form Glucose 1-Phosphate

26

Homopolysaccharide

Heteropolysaccharide 

  • Homopolysaccharide = polysaccharide made up ot only one type of monosaccharide.
  • Heteropolysaccharide = polysaccharide made up of multiple types of monosaccharide.

27

Draw glucose without a ring.

Draw the α-anomer and β-anomer of glucose

α-anomer: Anomeric Hydroxyl points down

 β-anomer: Anomeric Hydroxyl points up.

  • When converting from straight chain Fischer projection to cyclic Haworth projection

    • Everything to the right faces down on the Haworth

    • Everything to the left faces up on the Haworth 

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28

Enol

A compound that has a hydroxyl group on one side of a carbon-carbon double bond.

 

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29

Define Deoxy sugar

a sugar that has its hydroxyl group replaced by hydrogen.

"De"_"Oxy" = Oxygen is detatched

30

Triose

Tetrose

Pentose

Hexose

Triose - sugar with 3 carbons

Tetrose - with 4 carbons

Pentose - with 5 carbons

Hexose - with 6 carbons

31

Define lactone

structure?

This is tested on the MCAT

When a cyclic aldose carbohydrate is oxidized to a cyclic ketone carbohydrate.

 

It contains a cyclic ester (RC=O OR)

 

Same structure as glucose, but C-1 has a carbonyl

 

 

 

 

 

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32

How do you know if a carbohydrate is D- or L-?

Put the carbohydrates in Fischer projections and determine what side the most oxidized carbon holds its hydroxyl group on.

  • D: hydroxyl is on right side of most oxidized C
  • L: hydroxyl is on left side of most oxidized C

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33

Starch

What are the two types of starch and define them.

What are their properties?

Polysaccharide that is made up of α-D-glucose molecules.

  • Amylose - starch of α-D-glucose molecules linked by α-1,4 glycosidic bonds.
  • Amylopectin - highly branched starch of             α-D-glucose molecules linked at first by α-1,4 glycosidic bonds and then α-1,6 glycosidic bonds
    • Because it is highly branched, it is more souble due to increased interactions with the surrounding solution

 

34

Ketose

carbohydrate with a ketone as their most oxidized group

35

Epimers?

Epimers are a type of diasteriomer where both compounds differ at only one chiral center. 

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36

Hemiacetal/Hemiketal vs Acetal/Ketal

Which ones are the cyclic forms and noncyclic forms of carbohydrates.

Hemiacetal/Hemiketal: Cyclic forms

Acetal/Ketal: Noncyclic forms

37

Monosaccharide

 

What parts of it are a nucleophile and an electrophile?

a simple carbohydrate which contains a hydroxyl group and a carbonyl group.

 

The hydroxyl group is the nucleophile.

Carbonyl group is the electrophile.

38

Dissacharides

two monosaccharides conencted by a glycosidic bond between their anomeric carbons.

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39

Which is the more stable form of D-glucose:

α-anomer or β-anomer? Why?

  • β-anomer is more stable because it's anomeric hydroxyl occupies the equitorial position in the chair.
    • Has less steric hindrance

 

  • α-anomer is less stable because it's anomeric hydroxyl occupies the axial position in the chair
    • Causing steric hindrance

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40

Lactose

dissacharide made up of  D-glucose and D-galactose.

  • Connected by β-1,4 glycosidic linkage
  • Galactose-Glucose
    • Remember: Galactic nerds are beta-males

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41

how do you determine if a sugar is D- or L-?

 

 

does this tell us what direction it rotates plane polarized light in?

You look at the last numbered chiral carbon that points horizontal on a fischer projection and see what side the hydroxyl is on

 

D = hydroxyl faces right

L = hydroxyl faces left

 

No, D- and L- do not tell us what direction they rotate plane polarized light

lowercase d- and l- are used to designated deirection of plane polarized light 

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42

is cyclic glucose a hemiketal or hemiacetal compound?

Why?

 

Draw the formation of cyclic glucose

Steps?

glucose has an aldehyde group

thus, cyclic glucose is a hemiacetal compound

 

steps in the picture

 

α-anomeric carbons have hydroxyls that point down

  • Remember: α-males are on bottom and let the bitch ride the dick

β-anomeric carbons have hydroxyls that point up

 

 

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43

What are glycosidic linkages?

covalent bonds between a carbohydrate (sugar) and another group

the other group may or may not be a carb

44

what are the only two stable cyclic sugars?

 

why?

six-membered pyranose rings

and

five-membered furanose rings

 

due to ring strain

45

Which configuration is more stable and why?

 

α-anomeric carbon sugar or β-anomeric carbon sugar

  • β-anomeric carbon sugars are the most stable because the hydroxyl is pointing up in the equatorial position.
    • Equatorial does not cause steric hindrance, thus, most stable
  • α-anomeric carbon sugars are less stable because the hydroxyl is pointing down in the axial position
    • Causes steric hindrance.
    • Remember: α-males are not stable and can fuckup someone at any second.

46

Glycosidic linkage formation

Glycoside

Steps? Draw the mechanism.

what is formed?

  1. The hemiacetal or hemiketal cyclic sugar is attacked by a nucleophilic hydroxyl of another compound. 
  2. Hydrolysis occurs: water is removed
    • OH of anomeric carbon is removed
    • H of nucleophilic hydroxyl is removed
  3. The anomeric carbon connects to the nucleophilic oxygen and its compound, thus becoming an acetal or a ketal
    • Acetal - carbon connected to 2 OR groups; in a molecule that had an aldehyde
    • Ketal- carbon connected to 2 OR groups; in a molecule that had a ketone
  4. This new compound with a glycosidic linkage is called a glycoside, which is a complex sugar
    • disaccharide, oligosaccharide, or polysaccharide.

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47

Are lipids or carbohydrates (glycogen) better for energy storage?

Why?

Lipids are best for energy storage 

2 reasons

  1. Lipids have more reduced carbon atoms with hydrogen, which yield more energy when oxidized​
  2. Lipids are nonpolar hydrophobic, so they are lighter weight cause they don't need hydration

48

what do plants use for energy storage?

What forms is it in?

structures?

plants use starch, instead of glycogen, for energy storage

 

Starch comes in 2 forms:

  1. Amylose (alpha 1-4 glucose-glucose connections)
  2. Amylopectin (alpha 1-4 and alpha 1-6 branch glucose-glucose connections

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49

What cells are able to get glucose in the absence of insulin?

The brain and liver are able to absorb glucose without needing insulin

 

Neurons and Hepatic cells

50

Where is glycogen located in the body?

 

Where is it found in very large amounts?

Glycogen is found in all animal cells

 

It is found in very large amounts in muscle and liver cells