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MC Biochem 1 > Chpt 11- Carbohydrates > Flashcards

Chpt 11- Carbohydrates Flashcards

1
Q

Carbohydrates Definition

A
  • an aldehyde or ketone derivative of a polyhydroxyl compound (having more than one hydroxyl group)
  • Old def-hydrate of carbon (CH2O)n
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2
Q

Counting Saccharides

A 
Saccharide=Sugars (-ose)
3 Carbons- trios
4 Carbons- Tetrose
5 Carbons- Pentose
6 Carbons- Hexose
7 Carbons- Heptose
8 Carbons- Octose
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3
Q

Function of Carbohydrates

A
  • energy source (glucose or sucrose)
  • energy storage molecules (starch in plants, glycogen in animals
  • structural components (DNA and RNA)
  • Cell signaling molecule
  • Cell to cell recognition (Glycosylation of proteins and other biomolecules)
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4
Q

Isomer

A

Molecules with identical molecular formulas but different structural formulas

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5
Q

Enantiomer

A
  • Differ in configuration around one chiral carbon
  • mirror images
  • D or L (living systems contain D)
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6
Q

Epimer

A
  • one of two optical isomers that differ from each other only in the configuration about one asymmetric carbon aton
  • during cyclization
  • alpha or beta
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7
Q

Diasteromer

A

-one of two or more optical isomers of a component that are not enantiomers (possible due to multiple asymmetric carbons)

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8
Q

Different ways of Classifying Carbohydrates

A
  1. Classified by repeating Structural element
  2. Monosaccharides are classified as Aldose or Ketose
  3. Cyclized Monosaccharides are classified as Alpha or Beta
  4. Monosaccharides are classifies as Furanose and Pyranose
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9
Q

Classification of Carbohydrates:

Repeating Structural element

A
  • Monosaccharide (one)
  • disaccharide (two)
  • Oligosaccharide (more than 9)
  • polysaccharide (ALOT)
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10
Q

Classification of Carbohydrates:

Monosaccharides as Aldose and Ketose

A

Aldose-contains an aldehyde group

Ketose-contains a ketone group

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11
Q

D-Aldoses and D-ketoses you need to know:

A

D-Aldoses: (-ose)

1) D-Glyceraldehyde (3 Carbons)
2) D-erythrose (4 Carbons also D-ketoses)
3) D-ribose (5 Carbons and also D-ketose)
4) D-glucose (6 carbons)
5) D-mannose (6 carbons)
6) D- galactose (6 carbons)

D-Ketoses (-ulose)

1) Dihydroxyacetone (3 Carbons)
2) D-erythrulose (4 carbons also D-Aldose)
3) D-ribulose (5 carbons also D-Aldose)
4) D-fructose (6 carbons)

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12
Q

Classifying Carbohydrates:

Cyclized Monosaccharides are classified as Alpha or Beta

A

> 5 carbons cyclize into ring form
-in vivo <1% exist in linear form

Cyclization produces anomeric carbon-new chiral carbon

Alpha HYDROGEN Above
Beta HYDROGEN Below

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13
Q

Hemiacetal

A

formed by reacting aldehyde with an alcohol

5-membered ring (furanose)

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14
Q

Hemiketal

A

formed by reacting ketone with an alcohol

6 membered ring (Pyranose)

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15
Q

Classifying Carbohydrates:

Monosaccharides are classified as Furanose and Pyranose

A

Furanose- 5 membered ring
Pyranose- 6 membered ring
*Fructose can form both Furanose and Pyranose rings

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16
Q

Cyclic Conformations of 6 membered ring

A

Chair conformation is more stable than boat conformations due to steric hindrance

  • Axial-nearly perpendicular to the average plane of the ring (stick straight up or down)
  • Equatorial- atoms nearly parallel to the average plane of the ring (stick slightly up or down)
  • Furanose rings assume envelope form
  • C-2 or C-3 out of plane on the same side as C-5
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17
Q

Monosaccharides Mofications

A
  • Hydroxylation- O glycosidic bonds
  • Amine groups attach through N linked glycosidic bonds
  • Phosphorylated (PO32) ***
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18
Q

Phosphorylation of Carbohydrates

A

Key metabolic intermediates
Sugars become negatively charges (anionic)
-“Locks” the intermediates into the cell or other membrane bound compartment
-activates the intermediate

19
Q

Reducing vs NonReducing Sugars

A

Reducing sugars have a free aldehyde group or are capable of forming an aldehyde through ring opening, isomerization, or tautomerization
-some ketone groups may through tautomerization be reducing

20
Q

Tests for reducing sugars

A

Benedicts Reagent (CuSO4/Citrate)

Fehling’s Solution (CuSO4/tartrate)
-reducing sugars reduce copper (II) to copper (I). The produce, copper (I) oxidize, forms a red precipitate

Tollen’s Test (silver mirror test)
Tollen’s reagent precipitates silver metal when exposed to free aldehydes

21
Q

Glycosidic Bonds

A
  • Connects monosaccharides into: dimers, trimers, oligosaccharides, or polysaccharides
  • Condensation (dehydration) reaction
  • Two orientations: alpha or Beta
22
Q

What are the disaccharides we need to know?

A

Maltose
Lactose
Sucrose

23
Q

Maltose

A

Disaccharide
(alpha-D-glucopyranosyl-1,4-alpha-D-glucopyranose)
Glucose alpha-1,4-Glucose

Breakdown produce to glycogen/starch

24
Q

Lactose

A

Disaccharide
(B-D-galactopyranosyl-1,4-alpha-D-glucopyranose)
Galactose B-1,4-Glucose

Mammals milk sugar

25
Sucrose
Disaccharide (alpha-D-Glucopyranosyl-1,2-B-D-fructofuranoside) Glucose alpha 1,2 fructose table sugar
26
Polysaccharides we need to know for class?
Glycogen Starch Cellulose
27
Glycogen
Polysaccharide Monomer-Glucose Bond-connect alpha-1,4- with alpha 1,6 branches Function-animal energy (glucose) storage and stored in liver and muscle
28
Starch
Polysacchardie Monomer- glucose Bond-connected alpha-1,4 with alpha 1,6 branches Function: Plant energy (glucose) storage
29
Cellulose
Polysaccharide Monomore-glucose Bond: connected B-1,4 linear polymer of glucose function: plant structural fiber
30
Structure of Glycogen and Starch
Both are branched polymers of glucose connected by alpha 1,4 glycosidic bonds with alpha 1,6 branches Glycogen has more branches than starch
31
Proteoglycans
are glycosolated proteins that serve as joint lubricants and structural components in connective tissue
32
Glycosaminoglycans
are the carbohydrate component of proteoglycans | -repeating disaccharides of amino sugars
33
Mucopolysaccharidoses
diseases caused by the inability to degrade glycosaminoglycans (carbohydrate component of proteolglycans) Skeletal deformities and reduced life expectancy
34
Osteoarthritis
Disease caused by breakdown of proteoglycans
35
Glycosyltransferases
``` class of enzymes that catalyzes the formation of glycosidic bonds -use sugar nucleotide intermediates ``` the genes for specific glycosyltransferases are inherited in the Mendelian Pattern
36
ABO blood types
due to different carbohydrates on the surface of RCBs O antigen group is foundation - contain four carbohydrates (fucose, 2 copies of Galactose, N-actetylglucosamine) - modified to form A and B antigens A antigen -added N-acteylgalactosamine B antigen -added galactose
37
Proteins Modification in relation to carbohydrates
Proteins are modified by Attachment of carbohydrates 1) N linked carbohydrates are attached to the R group of asparagine 2) O linked carbohydrates are attached to the R group of Serine or Threonine For both: -Glycosylation sites identified by consenses sequences Asn-X-Ser or Asn-X-Thr, where X can't be proline
38
N-linked Oligosaccharides
Extensive modification leads to vast array of molecular shapes
39
EPO
Erythropoietin Function-stimulates the production of RBCs -Glycoprotein hormone; secreted kidney Structure: - 165 amino acids - 3 N-linked groups - 1 O-linked Group Uses: - Treats anemia cancer patients - Performance enhancement by athletes (Lance Armstrong)
40
Cellular Localization: N-linked Carbohydrates Glycoproteins O-linked carbohydrates
N-linked carbohydrates: - are attached/modified in thee lumen of the Endoplasmic Reticulum - are modified in the lumen of the golgi Glycoproteins: -are usually found on cell surface O-linked carbohydrates: -are attached in Golgi and cytoplasm
41
N Linked Carbohydrates Synthesization
are synthesized as a performed unit and transferred to newly synthesized proteins -assembled on a Dolichol phosphate in Lumen of ER
42
Lectins: | Function and Structure
specific carbohydrate binging proteins Legere (to select) Function- cell to cell interaction Structure: classified based on: amino acid homology and biochemical properties
43
Digestion of Carbohydrates
1) Mouth Mastification mixes salivary alpha amylase with dietary starch 2) Stomach digestion halts (inhibits alpha amylase) due to low PH 3) small intestine -acid neutralized by bicarbonate (from pancreas) -alpha amylase (from pancreas-continues digestion) 4) Mucosal lining of upper jejunum -Disaccharidases, oligosaccharidases-isomaltase, maltase, sucrase -secreted by luminal side of the brush border of intestinal mucosal cells

MC Biochem 1 (30 decks)

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