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Biochemistry Exam 2 > Carbohydrate Structure > Flashcards

Carbohydrate Structure Flashcards

1
Q

What are the 3 types of isomers?

A

Constitutional
Configurational
Conformational

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2
Q

Describe constitutional isomers

A

The order of the atoms changes

All constitutional isomers are Tautomers- fluctuate between the alcohol and the carbonyl group

If the alcohol points to the right on the fisher projection it is D
If it points to the left, it is L

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3
Q

_____ _______are the linear versions of the carbohydrates

A

Fisher Projections

*Note that the carbon numbering starts at the carbonyl/alcohol end of the aldose

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4
Q

Describe Stereoisomers

A

They have the same connectivity, but different spatial organizations

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5
Q

Describe configurational isomers

A

They have chiral carbons- 4 different groups attached to a single carbon

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6
Q

What are enantiomers?

A

Mirror images at all chiral centers

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7
Q

What are diastereomers?

A

Not mirror images at every chiral center, but note that they do have multiple chiral centers

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8
Q

______ _______ are the cyclical versions of carbohydrates

A

Hawthorn Projections

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9
Q

For the ring form (Hawthorn projection), where is the anomeric carbon?

A

Whichever carbon is attached to 2 oxygens

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10
Q

For the Fisher projection (linear form), how can you tell which is the anomeric carbon?

A

It will be the carbon that starts its life as a carbonyl because it loses the double bond and gains an oxygen when converted to the ring form

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11
Q

When the carbonyl in the fisher projection is converted into an alcohol in the Hawthorn projection, if the alcohol on the anomeric carbon is pointing up what does this mean and if it is pointing down what does this mean?

A

Up- Beta

Down- Alpha

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12
Q

What is an anomer?

A

They differ at the anomeric carbon only, example: alpha verses beta orientation

*Note that an anomer is a type of diastereomer

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13
Q

What is an epimer?

A

Differ at any other carbon than the anomeric carbon

  • Note that this means they must have the same alpha or beta orientation
  • Note that an epimer is a type of diastereomer
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14
Q

If during the fisher projections the alcohols are on the LEFT side, what does this mean for the Hawthorn projections?

A

They will be pointing up

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15
Q

If during the fisher projections the alcohols are on the RIGHT side, what does this mean for the Hawthorn projections?

A

They will be pointing down

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16
Q

What are the 2 conformations for a 4 membered ring and what is that ring called?

A

Furanose- 4 membered ring

C-3’- endo
C-2’-endo

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17
Q

What are the 2 conformations for a 6 membered ring and what is that ring called?

A

Pyranose- 6 membered ring

Boat
Chair

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18
Q

What are the 4 aldoses we need to know, and how many carbons are in each?

A

Glyceraldehyde- Triose (3)
Ribose- Pentose (5)
Glucose- Hexose (6)
Galactose- Hexose (6)

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19
Q

What are the 3 ketoses we need to know, and how many carbons are in each?

A

Dihydroxyacetone- Triose
Ribulose- Pentose
Fructose- Hexose

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20
Q

Take a look at slide 23, lecture 19 and know the structures of the sugars and how to convert them to eachother

A

Do this

21
Q

How do we form Fucose (yes this is the right spelling)

A

It is a Galactose derivative, at position carbon 6 the alcohol has been exchanged for a methyl

22
Q

What s the only L-monosaccharide made and used by mammals?

A

Fucose

23
Q

How is Fucose important?

A

Part of the A/B/O blood antigens

Excess free fucose in the blood shows signs of:
Liver damage
Cancer
Diabetes
Heart Disease
24
Q

How is phosphorylation important for modifying monosaccharides?

A

Part of nucleic acid structure

Adds a negative charge

25
Q

Where do we get the phosphate from during phosphorylation of monosaccharides?

A

ATP

26
Q

How do we know where the phosphate goes during phosphorylation of monosaccharides?

A

The name tells you where to put it…

Glucose-6- phosphate… you replace the hydrogen on carbon 6 with a phosphate

27
Q

When oxidizing monosaccharides, where does the acid attack the ring?

And what 2 strucutres can oxidizing a monosaccharide make? (how many rounds of oxidation to get to each structure)

A

The acid (in our case hydroxyl) attacks the anomeric carbon and expose it

By doing this, we make acids and lactones

  • Acids are made after one round of oxidation
  • Lactones are made after 2 rounds of oxidation
28
Q

What does reducing a monosaccharide at the carbonyl make?

Give an example

A

Alditols

Example: Sorbitol can cause cataracts if it accumulates in the lens of the eye

29
Q

Describe amino sugars modification of monosaccharides. Where are they found, how are they made?

A

Found in branched polysaccharides (Ex. cell walls)

Formed by N-linked glycosides:

  • Amine group
  • Acetyl group
  • Lactic Acid

*Note that the amine group always has to be directly attached to the ring. If the sugar does not have an amine group already present, whatever modification is being added must start with an amine.

30
Q

What is the difference between glucose and galactose in the ring conformation?

A

Glucose has its hydroxyl at carbon 4 pointing down

Galactose has its hydroxyl at carbon 4 pointing up

31
Q

During the methylation modification to a monosaccharide, where will the methyl group be added?

A

To put a methyl group on a monosaccharide, it must be connected to an alcohol because the oxygen will attack the anomeric carbon to add the methyl group

32
Q

Describe the O-linked glycosides modification of monosaccharides. What 2 toxins utilize this method and what are the effects of each?

A

Oubain- monosaccharide attached to a steroid. Locks the Na/K pump in the E2 conformation so there is an accumulation of Na because it cannot be released.

Amygdalin- disaccharide attached to a weird group with a cyanide on it. This releases cyanide, which is really bad.

33
Q

What are the essential Monosaccharides?

What are their structures

A

D-Glucose
D-Galactose
D-Mannose
D-Xylose (don’t need to know the structures)

34
Q

What are the 3 essential amino sugars?

A

GlcNAc- Glucose with amino acetyl group attached

GalNAc- Galactose with amino acetyl group attached

Sialic Acid

35
Q

What are the monosaccharides that make up the disaccharide, Maltose? What is the name of the connection for Maltose?

Slide 33- lectue 19

A

Glucose + Glucose

alpha- D- Glucopyranosyl (1–> 4) alpha- D Glucopyranose

36
Q

What are the monosaccharides that make up the disaccharide, Sucrose? What is the name of the connection for Sucrose?

Slide 33- lectue 19

A

Glucose + Fructose

alpha- D- Glucopyranosyl (1 –> 2) Beta- D-Fructofuranoside

37
Q

What are the monosaccharides that make up the disaccharide, Lactose? What is the name of the connection for Lactose?

Slide 33- lectue 19

A

Glucose + Galactose

Beta-D- Galactopyranosyl (1–>4) Beta-D- Glucopyranose

38
Q

What is the role of Sucrose?

A

A final product of photosynthesis, used as a primary source of energy in organisms that photosynthesize

39
Q

What is the role of Lactose?

A

Major animal energy source

40
Q

What is the role of Maltose?

A

A major circulatory sugar in insects, used for energy

41
Q

What are the 3 roles of Polysaccharides?

A
  1. Glucose Storage
  2. Structure
  3. Protein Diversity
42
Q

Describe the 1st role of polysaccharides, Glucose Storage. Give 2 examples

A

Less compact than lipid storage because it likes to interact with water therefore making it more volumenous

Amylopectin- branched
Amylose- unbranched

43
Q

Describe the 2nd role of polysaccharides, Structure.

A

Cellulose- Beta sheets. (1–> 4) Beta linkage

Chitin- is universal in providing structure. (1–>4) Beta linkage

44
Q

Describe the 3rd role of polysaccharides, Protein Diversity. What are the overall 2 types?

A

N-linked (Only amino acid that attaches the protein to the monosaccharide is Asparagine, Asn)

O-linked (Only amino acids that attach the protein to the monosaccharide are Serine or Threonine)

45
Q

Describe the 3rd role of polysaccharides, Protein Diversity. What are the 3 types?

A

Glycoproteins
Glycosaminoglycans
Mucins

46
Q

What is the role of Glycoproteins in terms of adding protein diversity and what is the stipulation to be added?

A

Protein > Sugar (by weight) - Stipulation

On membrane proteins –> cell adhesion
On soluble proteins –> cell signaling

Example: Erythropoietin is a glycoprotein hormone that stimulates RBC production

47
Q

What is the role of Glycosaminoglycans in terms of adding protein diversity and what is the stipulation to be added? What is it made up of?

A

Sugar > Protein (by weight)- Stipulation

Repeating disaccharide units

These are the sugar components for proteoglycans and they are important for:

  • Carilage
  • Blood clotting
  • Chitin
48
Q

What is the role of Mucins in terms of adding protein diversity and what is the stipulation to be added?

A

Sugar > Protein (by weight)

Lubrication= protection + hydration

49
Q

What are glycolipids used for and where are they found? How do you convert between A, B, and O in terms of glycolipids?

A

Found on the surface of cell memebranes and are used to recognize self from nonself.

O –> B by adding Galactose
O –> A by adding GalNAc

Biochemistry Exam 2 (13 decks)

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