Carbohydrate Metabolism

Question 1

What is Carbohydrate ?

Answer 1

Carbohydrates are called carbohydrates because they are essentially
hydrates of carbon (i.e. they are composed of carbon and water and
have a composition of (CH2O)n.

Question 2

Carbohydrate - 2

Answer 2

Simple Carbohydrate :

• sugars
  – monosaccharides – single sugars
  – disaccharides – 2 monosaccharide

Complex carbohydrates

starches and fibers
• polysaccharides
– chains of monosaccharides

Question 3

Glucose

Answer 3

Glucose
– Important energy source for the brain and red blood cells. and ½ of
energy for muscles and tissues.
• Glucose is immediate energy
• Can be stored as glycogen (reserve energy)

Question 4

Carbohydrate

Answer 4

Generates energy anaerobically and aerobically
– Transforms to energy via four metabolic pathways
1. Glycolysis
2. Intermediate reaction pyruvate to acetyl CoA
3. Tricarboxylic acid (TCA) cycle
4. Electron transport chain

Question 5

Full Glicose

Answer 5

If/when glycogen stores are full
 Tryglyceride synthesis
• Glucose converted to glycerol
and fatty acid
 Amino acid synthesis

Question 6

Pyruvate

Answer 6

Pyruvate is transported across the inner
mitochondrial membrane
Oxidized within the matrix to acetyl CoA
via Tri Carboxylic cycle (Krebs or citric
acid cycle) .

Question 7

Importance of Krebb cycle

Answer 7

Energy (2 ATPs per cycle) will be
produced from succinyl Co A (step 5).
• Other compounds produce NADH and
FADH2 for oxidative phosphorylation in
the mitochondria to make more ATP.

Question 8

Kreb

Answer 8

Kreb cycle (Citric acid cycle or TCA
cycle) is a amphibolic pathway:
Oxidative catabolism and
Provide precursor molecules for
anabolism, (particularly
gluconeogenesis.)

Question 9

Oxidation phosphorylation

Answer 9

Oxidative phosphorylation
– depends on electron transfer and the respiratory
chain linking to TCA cycle create proton gradient
across the inner membrane of mitochondria.
The proton gradient powers the synthesis of ATP
using ATP Synthase
When ETC blocked,
- no ATP is produced made
- only heat energy produced.

Question 10

Liver and Pancreas

Answer 10

Liver and Pancreas function is to regulate glucose levels in the blood:
– Liver responsible for storing the glucose
– Pancreas responsible for regulating the glucose available to cells

Question 11

Cells

Answer 11

Delta cells (10%) secrete somatostatin
slows the rate of food absorption and digestive enzyme
secretion

Alpha cells (25%) secrete glucagon
elevates blood glucose concentrations

Beta cells (60%) secrete insulin
reduces blood glucose concentrations

Question 12

One of most important homeostatic systems for survival of mammals.
• Continuously protects the metabolism and the function of the body and
brain by preventing or limiting hypoglycemia.

Answer 12

Normal plasma glucose level: 65 to 70 mg/dL (3.6 to 3.9 mmol/L)