Lecture 15: Carbohydrate Structure & Function

Question 1

Carbohydrates contain at least three _____ atoms, a number of __________groups and usually an __________ group

Answer 1

Carbohydrates at least three carbon atoms, a number of hydroxyl groups, and usually an aldehyde/ketone group

Question 2

Glucose converted to glycogen or __________\_ for storage

Answer 2

Glucose converted to glycogen or triacylglycerols (TAG) for storage

Question 3

Monosacharides

Answer 3

Question 4

Glucose: _______\_

_______\_ group at the end

Answer 4

Glucose: Hexoaldose

Aldehyde group at the end

Question 5

Fructose = _______\_

______\_ group usually at C2

Answer 5

Fructose = ketohexose

Ketone group usually at C2

Question 6

Nearly all sugars found in the body have the _________\_

This is because humans can not use the ___________\_ Enantiomer

Configuration of chiral carbon furthest from the aldehyde/ketone group determines the configuration

Answer 6

Nearly all sugars found in the body have the D configuration

This is because humans can not use the L configuration Enantiomer

Configuration of chiral carbon furthest from the aldehyde/ketone group determines the configuration

Question 7

__________: Same chemical formula but the position of hydroxyl group different at one or more of the asymmetrical carbons.

• 3 commonly found?

Answer 7

Stereoisomer: Same chemical formula but the position of hydroxyl group different at one or more of the asymmetrical carbons

• Only three are found in significant amounts:
  
  • D-Glucose
  • D-Mannose
  • D-Galactose

Question 8

_____________: hydroxyl group on anomeric carbon is:

• On the right in the Fischer projection
• Below the plane in Haworth projection

Answer 8

αconfiguration: hydroxyl group on anomeric carbon is: ‘right below’

• on the right in the Fischer projection
• Below the plane in Haworth projection

Question 9

___________\_: The C of the C=O group

Answer 9

Anomeric Carbon: The C of the C=O group

Question 10

_____________: hydroxyl group on anomeric carbon is:

On the left in the Fischer projection

Above the plane in Haworth projection

Answer 10

Beta Configuration: hydroxyl group on anomeric carbon is:

On the left in the Fischer projection

Above the plane in Haworth projection

Question 11

_________________bond forms between the anomeric carbon of a monosaccharide and the

hydroxyl/-NH group of another compound.

Answer 11

Glycosidic bond forms between the anomeric carbon of a monosaccharide and the hydroxyl/-NH group of another compound

Usually 1,4 glucosidic bond. Can also be 1,6

Question 12

Monosaccharides linked to other monosaccharides via _____________\_

Monosaccharides can be linked to non-carbohydrates via ___________\_

Answer 12

Monosaccharides linked to other monosaccharides via O-glycosidic bonds (oxygen)

Monosaccharides can be linked to non-carbohydrates via N-glycosidic bonds (nitrogen)

Question 13

_________, __________, and ________\_ are the main disaccharides

Answer 13

Sucrose (table sugar), lactose (milk sugar), and maltose are the main disaccharides

Question 14

Cells store glucose in homopolymers to reduce the _________ of stored glucose

Answer 14

Cells store glucose in homopolymers to reduce the osmotic pressure of stored glucose

Question 15

________________:

• Monomers of glucose with 1,4 and periodic 1,6 bonds and branch points in the chain
• Highly branched with frequent alpha 1,6 linkages giving rise to short branch chains

Answer 15

Glycogen:

• Monomers of glucose with 1,4 and periodic 1,6 bonds and branch points in the chain
• Highly branched with frequent alpha 1,6 linkages giving rise to short branch chains

Question 16

________________:

• Monomers of glucose with 1,4 and periodic 1,6 bonds and branch points in the chain
• Occurs as unbranched amylose or branched amylopectin w/ infrequent 1,6 linkages and long side chains

Answer 16

Starch:

• Monomers of glucose with 1,4 and periodic 1,6 bonds and branch points in the chain
• Occurs as unbranched amylose or branched amylopectin w/ infrequent 1,6 linkages and long side chains

Question 17

____________ –major component of plant cell walls is also a homopolymer of glucose

• Glycosidiclinkages are in the ________\_instead of ________\_ as seen in starch and glycogen
• Insoluble in water due to high affinity of polymer chains for one another

Answer 17

Cellulose –major component of plant cell walls is also a homopolymer of glucose

• Glycosidiclinkages are in the β-(1,4) configuration instead of α-configuration as seen in starch and glycogen
• Insoluble in water due to high affinity of polymer chains for one another

Question 18

________\_ of glucose is the first step in glycolysis and is facilitated by the enzyme_______

(_______\_ in the liver)

Answer 18

Phosphorylation of glucose is the first step in glycolysis and is facilitated by the enzyme hexokinase

(glucokinase in the liver)

Question 19

Answer 19

Question 20

_____________:

• one of the most abundant monosaccharides
• Precursor for the formation of glycosylated proteins and lipids
• Found in the fluid around joints

Answer 20

Glucosamine:

• one of the most abundant monosaccharides
• Precursor for the formation of glycosylated proteins and lipids
• Found in the fluid around joints

Question 21

_________\_ are a class of sugar acids with both carbonyl and carboxylic acid functional groups

Answer 21

Uronic Acids are a class of sugar acids with both carbonyl and carboxylic acid functional groups

Question 22

________ is involved in the solubilization of bile acids –makes lipid compounds more water-soluble

Answer 22

Glucuronic acid is involved in the solubilization of bile acids- makes lipid compounds more water-soluble

Question 23

Sugars can be reduced to form alcohols:

• Glucose reduced to sorbitol by ________ and galactose to galactilol
• Sorbitol then converted to fructose by ____________

Answer 23

Sugars can be reduced to form alcohols

• Glucose reduced to sorbitol by aldose reductase and galactose to galactilol
• Sorbitol then converted to fructose by sorbitol dehydrogenase

Question 24

________ pathway:

____________ converts glucose into sorbitol during the first step in the polyol pathway. Sorbitol cannot readily cross the cell membrane and gets trapped within cells, which can lead to Cataracts in the eyes during hyperglycemia.

However, if the enzyme ___________ is present it can convert sorbitol into fructose

Answer 24

Polyol pathway:

Aldose Reductase converts glucose into sorbitol during the first step in the polyol pathway. Sorbitol cannot readily cross the cell membrane and gets trapped within cells, which can lead to Cataracts in the eyes during hyperglycemia.

However, if the enzyme Sorbitol Dehydrogenase is present it can convert sorbitol into fructose

Question 25

_\_\_\_\_\_\_\__ is a glycosylated pyrimidine-analog containing uracil attached to a ribose ring * Important intermediates in glycogen synthesis, formation of proteoglycans and glycolipids * _\_\_\_\_\_\__ donors of the attached sugar

Answer 25

_Uridine_ is a glycosylated pyrimidine-analog containing uracil attached to a ribose ring * Important intermediates in glycogen synthesis, formation of proteoglycans and glycolipids * _Active_ donors of the attached sugar

Question 26

Glycosaminoglycans (GAGs): * Synthesized from _\_\_\_\_\__ sugars * Polysaccharides made up of repeating _\_\_\_\_\__ units * Long unbranched polysaccharides * Highly charged and _\_\_\_\_\__

Answer 26

Glycosaminoglycans (GAGs): * Synthesized from _UDP_ sugars * Polysaccharides made up of repeating _disaccharide_ units * Long unbranched polysaccharides * Highly charged and _polar_

Question 27

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_: * Found in connective tissue, synovial fluid of joints, vitreous humor(eye), cartilage * Long linear chains of glycosaminoglycans(\_\_\_\_) attached to a core protein

Answer 27

_Proteoglycans_: * Found in connective tissue, synovial fluid of joints, vitreous humor(eye), cartilage * Long linear chains of glycosaminoglycans(_GAGs_) attached to a core protein

Question 28

_\_\_\_\_\_\_\_\_\_\_\_\__: * Enzymes, hormones, antibodies, and structural proteins. Cell-cell interactions * Less sugar and _\_\_\_\_\_\__ polysaccharide chains than proteoglycans which are usually branched * Branches grow by attaching to the amide nitrogen of an _\_\_\_\_\_\__ residue within the protein (ie. SPIKE protein in SARS CoV2 tutorial)

Answer 28

_Glycoproteins_: * Enzymes, hormones, antibodies, and structural proteins. Cell-cell interactions * Contain _smaller_ polysaccharide chains than proteoglycans that are usually branched * branches grow by attaching to the amide nitrogen of an A**_sparagine_** residue within the protein (remember SPIKE protein in SARS CoV2 tutorial?)

Question 29

Lysosomal enzymes are _\_\_\_\_\_\_\_\_\__and are labeled with _\_\_\_\_\_\_\__ to direct them to Lysozyme and prevent excretion from the cell.

Answer 29

Lysosomal enzymes are _glycoproteins_ and are labeled with _mannose-6 phosphate_

Question 30

_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_:_ * Mutations in phosphotransferase enzyme responsible for the addition of mannose-6-phosphate to lysosomal enzymes * Lysosomal function is impaired –lysosomes become engorged with non-digested material * Death ensues within the first 10 years of life

Answer 30

_I-cell disease:_ * Mutations in phosphotransferase enzyme responsible for the addition of mannose-6-phosphate to lysosomal enzymes * Lysosomal function is impaired –lysosomes become engorged with non-digested material * Death ensues within the first 10 years of life

Question 31

The pH of Lysosome versus Cell?

Answer 31

Lysosome (4.5-5) Cytoplasmic pH (7.2)