Carbohydrate Metabolism
How is glucose used and stored in the body?
1. Complex carbohydrates (polysaccharides) are ingested
starch from plants (wheat, rice, potatoes, and maize)
is broken
2. Excess glucose is stored in liver
3. Glycogen is broken down into glucose monomers to be used in glycolysis
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Carbohydrate Metabolism
Polysaccharides
Monosaccharide -
Oligosaccharides – linkage of ____________________________________
disaccharide of glucose
Polysaccharides - linkage of
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Carbohydrate Metabolism
Polysaccharides
Glycosidic bond - a bond between the #1 _________________________________
- can be between __________________________________
- bond can be in the __________ depending the OH orientation
around C#1
αβ-
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Carbohydrate Metabolism
Polysaccharides
Polysaccharides can be linear or branched
Two forms of starch:
1. amylose 2. amylopectin -
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Carbohydrate Metabolism
Glycogen
Glucose from ingested complex carbohydrates ______________________
Excess glucose is used to form ________________________.
During low glucose, glycogen can be broken down into glucose for glycolysis
Glycogen - a branched polymer _____________
- about _____________ units per glycogen molecule
- linear portions have ________________________
- branch points are __________________________
- 13: average chain length of glycogen branches
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Carbohydrate Metabolism
Glycogen
Break down of glycogen
- glucose is released from glycogen at
-  highly branched structure allows for release of many ______________
_____________________________
- allows for quick _____________________ at times of need
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Carbohydrate Metabolism
Glycogen breakdown
Glycogen phosphorylase - enzyme that releases
- uses Pi to phosphorylate glucose to G1P, breaks
Phosphoglucomutase - enzyme that isomerizes
- this G6P can then be put directly into
_________________
α-1,6 branch bond broke by
______________________
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Carbohydrate Metabolism
Glycogen breakdown
Glycogen phosphorylase - enzyme that releases _________________
- note that the phosphate for G6P formation from glycogen
- thus, glycolysis from glycogen
- net
from glycolysis
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Carbohydrate Metabolism
First step:
Glycogen formation
Energy for glycogen production from glucose uses _________________
____________________ to form uridine diphosphate glucose (UDPG)
UDP-glucose pyrophosphorylase - enzyme that carries out this reaction
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Carbohydrate Metabolism
Second step:
Glycogen formation
- UDPG is linked to another ________________________________
- carried out by __________________________________
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Carbohydrate Metabolism
Glycogen formation
Branching step:
- branching enzyme transfers 7 glucoses from ______________________
_____________________________________________
- forms _________________
- each transferred segment
comes from at least
- each branch point at least
4 glucoses
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Carbohydrate Metabolism
Glycogen formation
Why do athletes that perform endurance events (long distance
running, cycling) eat pasta before exercise?
Glycogen loading (carbo loading) - _________________________
__________________________________________
- extra glycogen allows for ______________________________
by anaerobic glycolysis during extended exercise
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Carbohydrate Metabolism
Gluconeogenesis
- Conversion of ___________________
- essentially ____________________, but not exactly
- _________________ of glucose
- occurs in ________________
- occurs in time of _________, __________, or intense _________
- requires energy (ATP) input
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Carbohydrate Metabolism
Gluconeogenesis
- Many of the steps in glycolysis are ________
- 3 steps in glycolysis are irreversible:
1. G6P production from ______________
_____________________
2. F1,6BP production from ___________
3. ________________________ from
phosphoenolpyruvate (PEP)
These reactions must be __________
in gluconeogenesis
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Carbohydrate Metabolism
Gluconeogenesis
Step 1. Conversion of pyruvate to __________
- carried out by enzyme __________________
- uses 1 ATP
- reaction takes place
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Carbohydrate Metabolism
Gluconeogenesis
Step 2. Conversion of oxaloacetate to
Mg2+
+ GTP
Phosphoenolpyruvate
carboxykinase
O
C
O-
O
C
O
P
CH2
+CO2 + GDP
O-
O-
phosphoenolpyruvate
- carried out by enzyme phosphoenolpyruvate
carboxykinase
- uses 1
instead of ATP
- reaction takes place in ________________
- now PEP is produced,
- PEP continues through gluconeogenesis
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Carbohydrate Metabolism
Gluconeogenesis
Step 9. Conversion of F1,6BP
11
10
9
8
6
7
-  carried out by enzyme ________________
___________________________
5
4
- removes __________________ from F1,6BP
3
2
- reaction takes place in ________________
1
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Carbohydrate Metabolism
Gluconeogenesis
Step 11. Conversion of G6P to _____________
11
10
9
8
6
7
- carried out by enzyme ________________
_______________________________
5
4
- removes phosphate from G6P
3
2
1
- reaction takes place in
Gluconeogenesis and glycolysis are not exact
reversals of each other,
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Carbohydrate Metabolism
Gluconeogenesis
11
Entry points for gluconeogenesis
10
1. Lactate can be
9
2. Amino acids can be converted to
8
6
7
3. Glycerol can be converted to
5
4
3
2
1
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Carbohydrate Metabolism
The Cori Cycle
- fast twitch muscle mostly carries out
.
- during exercise such as sprint
fast twitch muscles will _______
________________________
- lactic acid is transported _____
- lactic acid is converted to
glucose via _______________
- glucose is shuttled back to
__________________
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Carbohydrate Metabolism
The Cori Cycle
Why warm down or have massage after exercise?
- muscle soreness after exercise
- warm down or massage keeps
blood flowing to ____________
_______________________
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Carbohydrate Metabolism
The Cori Cycle
Carl Ferdinand Cori & Gerty Theresa Cori
- naturalized Americans
- born in Prague
- worked at the State Institute for the Study
of Malignant Diseases (now the Roswell
Park Cancer Institute) in Buffalo, New York
- defined Cori Cycle in 1929
- Nobel Prize in Physiology or
Medicine in 1947
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