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

Yield of ATP from the Complete Oxidation of One Glucose Molecule in a Skeletal Muscle Cell.

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

The relationships among 4 common metabolic pathways that involve glucose.

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 Cori cycle: processing lactate made during anaerobic exercise

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).

Epinephrine a.k.a. adrenalin

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

The series of events by which the hormone epinephrine stimulates glucose production.

Stimulates adenyl cyclaseto make cAMP

cAMP released to interior activates… Glycogen phosphorylase,

which starts glycogenolysis

Quick energy molecule glucose 6-phosphate forms