Review: can you… Explain how Carbs are digested & absorbed
Draw the steps involved in Glycolysis
Compare and contrast aerobic respiration to two different types of fermentation
Discuss the 3 possible fates of Pyruvate
Energyyield fromcomplete
oxidation ofglucose (e- loss)
via aerobicrespirationanaerobic
fermentation
results in
just 2 ATP30 to 34
Cell constituentNumber of molecules per cell
Molecules synthesized per second
Molecules of ATP required per second for synthesis
DNA 1 0.00083 60,000
RNA 15,000 12.5 75,000
Polysaccharides 39,000 32.5 65,000
Lipids 15,000,000 12,500.0 87,000
Proteins 1,700,000 1,400.0 2,120,000
How is all of that ATP used?
Just focusing on building molecules (synthesis);gives you a taste of ATP driven reactions.
Glycogen = animal starch (glucose storage molecule). Muscle: glucose source for glycolysisLiver: glucose source for maintenance of
blood glucose levels
Glucose is stored in muscles and liver :
Comparing glycogenesis to glycogenolysis
Separate pathway energy needs. Separate control of each pathway.
Gluconeogenesis:Needed to produce glucose for the brain
when food isn’t available.Glycogen stores are depleted
in 12 to 18 hours.Use other non-carbohydrate sources (glycerol,lactate, some amino acids, & (in plants) acetyl-CoA)
to make glucose for brain fuel.The liver is the major site of
gluconeogenesis.
What does your body do if you don’t have enough glucose?
The “opposite” (sort of) processes of gluconeogenesis (pyruvate to glucose)
& glycolysis (glucose to pyruvate) are not exact opposites.
Additional step due to energy needs
Gerti and Carl Cori won 1947 Nobel Prize in
physiology / medicine for discovery of the enzyme that starts the conversion of glycogen to glucose.
The Cori cycle is named after them.
The Pentose Phosphate Pathway (PPP)
DNA & RNA need 5-C sugar ribose, formed in pentose phosphate pathway (PPP). PPP is a
network of reactions (Glycolysis is largely a straight-thru pathway).
We can make different products depending upon body’s needs.
PPP generates various sugars (e.g. ribose), & also
produces NADPH, required by cells for biosynthesis rxns.
Hormonal Control of Carbohydrate Metabolism
• Enzymes control the metabolism of carbohydrates, but...
• Several hormones also affect Carb. metabolism– Insulin– Glucagon– Epinephrine
Insulin reduces glucose in the blood and stimulates conversion of glucose to fats, proteins,
ribulose 5-phosphate and glycogen;inhibits the conversion of fats, proteins, glycogen
and ribulose 5-phosphate to glucose
Types of diabetes mellitusType 1: autoimmune disorder against the lslet cells of pancreas: deficiency in insulin. Usually diagnosed between 5-20. Insulin shots necessary. Hypoglycemia (too little glucose) may result.
Type 2: 80-90 % of all diabetics in US: usually diagnosed over age 40. relative insulin deficiency: either decreased production of insulin, or cells become insulin resistant. Strong genetic component: very high in Native Americans; high in Blacks & Hispanics. Obesity major risk factor (often controlled with weight loss).
Glucagon is a 29 amino acid peptide hormone formed and released from the cells of the islets of Langerhans, in
the pancreas. Glucagon is a hormone that opposes the action of insulin
- mainly in the liver.
Epinephrine & glucagon have opposite effects to insulin. Act to increase glucose in the blood.
Stimulate conversion of fats, glycogen and pyruvate to glucose
Inhibit conversion of glucose to fats, glycogen and pyruvate
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