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My Packs: (WIZEPREP) (BIOCHEM 2280) > Chapter 7: 7.1 Carbohydrates > Flashcards

Chapter 7: 7.1 Carbohydrates Flashcards

1
Q

What are carbohydrates involved in?

A
  • Postranslational modifications
  • Cell recognition
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2
Q

What are carbohydrates also referred to as?

A

Sugars

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3
Q

Define:

Monosaccharides

A

The simplest carbohydrate
* Has the formula: (CH2O)n

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4
Q

How are carbohydrates named as?

A

Named based on the number of carbons they have
* E.x. triose, tetrose, pentose, hexose, heptose…

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5
Q

What are aldoses? What are ketoses?

A
  1. Aldoses: Carbohydrates have an aldehyde at C1
  2. Ketoses: Carbohydrates have a ketone at C2
  • E.x. Ketohexose, aldotriose…
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6
Q

In Fischer Projections:

What do L and D represent?

A

L and D are in reference to the different enantiomers of the sugar structure (asymmetry)

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7
Q

In Fischer Projections:

What do enantiomers depend on?

A

Dependent on the chiral carbon furthest from the carbonyl group

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8
Q

In Fischer Projections:

What does it mean that enantiomers are optically active?

A

Rotate polarized light either to:
* The right (+, D)
* The left (-, L)

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9
Q

In Fischer Projections:

What determines the possible number of stereoisomers? State the formula

A

The number of chiral carbons (x)
* Possible number of stereoisomers = 2^x

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10
Q

Describe:

Carbohydrate Cyclization

A

The hydroxyl group nycleophilically attacks the aldehyde or the ketone (very reactive) forming the ring

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11
Q

In carbohydrate cyclization:

What types of rings are formed?

A
  1. Furan (5 membered ring)
  2. Pryan (6 membered ring)
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12
Q

What types of bonds can be formed in carbohydrate cyclization?

A
  1. Hemiacetal (from aldehyde)
  2. Hemiketal (from ketone)
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13
Q

In carbohydrate cyclization:

It result in — possible ——-

A
  1. Two
  2. Anomers
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14
Q

What are the two possible anomers resulting from carbohydrate cyclization?

A
  1. α (E.x. α-D-Glucose)
  2. β (E.x. β-D-Glucose)
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15
Q

In carbohydrate cyclization:

Which anomer is more stable?

A

β

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16
Q

Define:

Isomers

A

Same formula, different structures

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17
Q

What types of stereoisomers are there?

A
  • Enantiomers
  • Diastereoisomers
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18
Q

Define:

Enantiomers

A

Mirror images (not superimposable)

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19
Q

Define:

Diastereoisomers

A

Not mirror images (superimposable)

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20
Q

Define:

Anomers

A

Differs at a new asymmetric carbon in the ring conformation

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21
Q

True or False:

Anomers are a type of diastereoisomer

A

True

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22
Q

Define:

Reducing Sugars

A

Sugars able to act as a reducing agent due to a free aldehyde or free ketone group (all monosaccharides)

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23
Q

In reducing sugars:

What are aldehydes converted to?

A

Converted to carboxylic acids

24
Q

In reducing sugars:

What are ketones converted to?

A

Tautomerized into aldehydes and then reduced to carboxylic acids

25
Q

True or False:

Disaccharides are reducing sugars

A

Partially true. Disaccharides are reducing sugars as long as one of the units have an open chain with an aldehyde

26
Q

Is maltose a reducing sugar? Is sucrose a reducing sugar?

A
  1. Maltose is reducing
  2. Sucrose is not reducing
27
Q

What modifications are made to make complex carbohydrates?

A
  • Phosphorylation
  • Methylation
  • Addition of N-containing groups
  • Hydroxyl groups removed
28
Q

Describe:

Naming of sugar complexes:

A
  • Monosaccharide = 1
  • Disaccharide = 2
  • Oligosaccharide = 3-20
  • Polysaccharides = 1000s
29
Q

Describe:

Disaccharide formation

A

Condensation reaction forming a glycosidic bond

30
Q

In disaccharide formation:

What type of glycosidic bonds are there?

A
  1. O-glycosidic bond
  2. N-glycosidic bond
31
Q

In disaccharide formation:

List the linkage to proteins

A
  1. O-linkages (to Ser/Thr)
  2. N-linkages (to Asn)
32
Q

Define:

Glycosyltransferase

A

The enzyme responsible for linking sugars via O-glycosidic bonds

33
Q

How does glycosyltransferase work?

A

Uses UPD-glucose to attach sugars onto other sugars or proteins

34
Q

Define:

UPD glucose

A

A high energy sugar nucleotide used by glycosyltransferase

35
Q

—— are cleaved into ————— via ——-

A
  1. Sugars
  2. Monosaccharides
  3. Enzymes
36
Q

True or False:

Monosaccharides are a source of fuel

A

True

37
Q

What enzymes are used to cleave sugars into monosaccharides?

A

Lactase, maltase, sucrase

38
Q

Explain:

Naming Disaccharides

A
  1. Identify N or O linkage
  2. Configuration of the first sugar plus the name ending in -yl
  3. The number identifiers of the carbons linked together
  4. Configuration of the second sugar plus the name ending in -ose
39
Q

What are polysaccharides also referred to as?

A

Glycans

40
Q

Describe:

Polysaccharides

A

Consist of 1000s of monosaccharides (linked either linearly or branched)

41
Q

Polysaccharides play roles in…

A
  • Energy storage
  • Cell structure
  • Cell recognition
42
Q

Define:

Homopolymers

A

Polysaccharides made up of the same repeating monosaccharide

43
Q

Define:

Heteropolymers

A

Polysaccharides made up of different monosaccharide repeats

44
Q

Define:

Glycogen

A

A energy storage homopolymer with a multibranched structure

45
Q

What is the repeating monosaccharide in glycogen?

A

Glucose

46
Q

Describe structure of:

Glycogen

A

Consists of branched glucose units surrounding a glycogenin protein at its core
* Chain lengths of 8-12 of linearly linked glucose molecules (α(1-4) glycosidic bonds) with branches forming α(1-6) glycosidic bonds

47
Q

What is starch comprised of?

A
  1. Amylose
  2. Amylopectin
48
Q

Describe structure of:

Amylose

A

Linear linkages of glucose (α(1-4) glycosidic bonds)

49
Q

Describe structure of:

Amylopectin

A

Linear linkages of glucose (α(1-4) glycosidic bonds) with α(1-6) glycosidic linkages occuring every 30 glucose units

50
Q

Explain the function of:

α-amylase

A

Cleaves glycogen and starch at random locations yielding maltose and maltotriose

51
Q

What secretes α-amylase?

A

Pancreas

52
Q

Explain the function of:

β-amylase

A

Hydrolyzes glucose units in glycogen and starch systematically at non-reducing ends, producing maltose

53
Q

True or False:

β-amylase is produced in the pancreas

A

False, β-amylase is not produced by mammals

54
Q

Define:

Cellulose

A

Structural components in plants

55
Q

Describe the structure of:

Cellulose

A
  • Formed by β(1-4) glycosidic linkages
  • Linear chains
  • Formula: (C6H10O5)n
  • More crystalline than starch
56
Q

True or False:

Cellulose is digestible by humans

A

False, cellulose is not digestible by humans

57
Q

List:

Common monosaccharides to know

A
  1. Glucose (Glucopyranose)
  2. Fructose (Fructofuranose)
  3. Galactose (Galactopyranose)
  4. Mannose (Mannopyranose)
  5. Ribose (Ribofuranose)
  6. Deoxyribose (Deoxyribofuranose)

My Packs: (WIZEPREP) (BIOCHEM 2280) (19 decks)

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