Metabolic Processes and Energy Production Overview

Catabolism

Breakdown of complex organic molecules.

Metabolism

•refers to all the chemical reactions in the body

•Utilizing Macromolecules called proteins, fats, carbs and nucleic acid .

Anabolism

Combination of simple molecules into complex ones.

ATP Generation

phosphorylation(ADP+P)= ATP

Carbohydrate Metabolism

Focuses on glucose metabolism.

Polysaccharides

Complex carbohydrates broken down into simple sugars.

•Liver cells convert much of the remaining fructose and practically all of the galactose to glucose

•carbohydrate metabolism is primarily concerned with glucose metabolism.

Monosaccharides

Simple sugars like glucose, fructose, and galactose.

In GI tract

•polysaccharides broken down into simple sugars

•absorption of simple sugars (glucose, fructose & galactose)

In liver

•fructose & galactose transformed into glucose

•storage of glycogen (also in muscle)

in body cells

•functions of glucose

•oxidized to produce energy

Glycolysis

First stage of cellular respiration, occurs in cytoplasm.

Krebs Cycle

Occurs in mitochondrial matrix, produces energy.

Electron Transport Chain

Final stage of respiration, occurs in inner membrane.

NADH

Electron carrier, reduced from NAD+.

FADH2

Electron carrier, reduced from FAD+.

Steps in glycolysis:

I) Investment stage

•Glucose is a 6 carbon molecule

•We invest an ATP. ATP is hydrolyzed to ADP+pi

•The phosphate group attaches to glucose and is called glucose 6-phosphate

•We invest an atp again. Atp is hydrolyzed to adp+ pi

•The phosphate group attaches to glucose 6-phosphate and is now called fructose 1,6-bisphosphate

II) Cleavage:

•Fructose 1,6 bisphosphate is split into 2-3 carbon molecules

•A) One called dihydroxyacetone which will be converted into glyceraldehyde 3-phosphate

•B) One already called glyceraldehyde 3-phosphate

III) Harvesting stage

•A) One called dihydroxyacetone which will be converted into glyceraldehyde 3-phosphate

•B) One already called glyceraldehyde 3-phosphate

•Each One glyceraldehyde 3-phosphate(B) will go through the harvesting

•glyceraldehyde 3-phosphate(B) also called G3P will continue the harvesting processes

•NAD+ is reduced to NADH at the same time adding a phosphate group to G3P

•We harvest by converting ADP+ a phosphate taken from G3P to give us atp

•We harvest by converting ADP+ a phosphate taken from G3P to give us ATP again

•We are left with a 3-carbon molecule called pyruvate

Glucose 6-Phosphate

First product of glucose phosphorylation.

Fructose 1,6-Bisphosphate

Intermediate formed from glucose 6-phosphate.

Glyceraldehyde 3-Phosphate

3-carbon molecule involved in glycolysis.

Pyruvate

End product of glycolysis, 3-carbon molecule.

End result of glycolysis

•NADH, 2 ATP and, 2 pyruvate were generated

•Pyruvate will be used to start kreb cycle

•NADH will be brought to ETC stage.

Pyruvate Oxidation

Conversion of pyruvate to Acetyl-CoA.

Acetyl-CoA

2-carbon molecule from pyruvate oxidation.

Oxaloacetate

4-carbon molecule that combines with Acetyl-CoA.

Citrate

6-carbon molecule formed in Krebs cycle from the combination of oxaloacetate and acetyl coA

Krebs Cycle

Metabolic pathway producing energy from acetyl CoA.

Kreb cycle steps

Citrate is converted to isocitrate(6-carbon)

Isocitrate is oxidized, releasing a carbon molecule. This give us C02 NAD+ is reduced to NADH and a-ketoglutrate( 5-carbon molecule)

a-ketoglutarate(5-carbon molecule) is oxidized, releasing a carbon molecule. This give us C02, NAD+ is reduced to NADH, and giving us Succinyl coA(4-carbon molecule)

Succinyl coA(4-carbon) is synthesized into succinate(4-carbon), and ADP is hydrolyzed to ATP

Succinate(4-carbnon) is oxidized to fumrate(4-caarbon), and at the same time FAD---FADH2

Water is added to fumrate(4-carbon) to give malate(4-carbon)

Malate(4-carbon) is oxidized to give oxaloactate(4-carbon) and at the same time NAD+ is reduced to NADH

Mitochondrial Matrix

Site of Krebs cycle reactions.

Glycolysis Products

Generates 2 NADH, 2 ATP, and 2 pyruvate.

a-ketoglutarate

5-carbon molecule in Krebs cycle.

Succinyl coA

4-carbon molecule formed from a-ketoglutarate.

Succinate

4-carbon product from Succinyl coA.

Fumarate

4-carbon molecule formed from succinate.

Malate

4-carbon molecule formed from fumarate.

End of kreb cycle

•1st round: 3 NADH, 1 ATP and 1 FADH2

•2nd round: 3 NaDH, 1 aTP and 1 FADH2

Total Yield (Krebs Cycle)

6 NADH, 2 ATP, 2 FADH2 after two rounds.

Electron Transport Chain (ETC)

Series of proteins transferring electrons to create ATP.

Oxidative Phosphorylation

Process of ATP production using electron transport.

Complex I

Oxidizes NADH, pumps protons into intermembrane space.

Complex II

Oxidizes FADH2, transfers electrons to coenzyme Q.

Coenzyme Q

Electron carrier transferring electrons to Complex III.

Complex III

Pumps protons and transfers electrons to Cytochrome C.

Complex IV

Final complex, transfers electrons to oxygen.

Chemiosmosis

Process using proton gradient to synthesize ATP.

ATP Synthase

Enzyme converting ADP to ATP using protons.

Triglycerides

Stored fats broken down into glycerol and fatty acids.Stored form of lipids in the body.

Lipids

•Lipids are made up of fats such as triglycerides, unsaturated/saturated fats.

•Lipid is broken down and synthesizes through the process of beta-oxidation

overall process of lipid metabolism

•the Triglycerides enters the blood and into the cell as fatty acid--the free fatty acids enters the mitochondria as acetyl coA-à transported into the mitochondrial matrix

•Keep in mind only cells with a mitochondria is where fatty acids can enter. So, nervous tissue and red bloods cells don't have fatty acids because they don't have a mitochondria

Beta-Oxidation

Process of breaking down fatty acids.

Three stages of beta oxidation(lipid metabolism)

•I) transport of fatty acids from adipose tissue to a targeted cell

•Triglycerides within the adipose tissue is broken down into glycerol and fatty acids lipase which is an enzyme breaks the bonds between glycerol and fatty acids

•Glycerol runs through glycolysis

•The free fatty acids that detached enters the blood and moves into any cell that can metabolizes fatty acids which means it should have a mitochondria

•The fatty acid enters the cytoplasm of any cells via a fatty acid transporter

•II) Entry into the cytoplasm of the targeted cell and into the mitochondria

•Before entering the mitochondria from the cytoplasm, the fatty acid needs to be converted into acetyl coA and this happens by using an enzyme called acetyl-CoA synthase

•Once converted, acetyl coA moves into the mitochondria matrix with the helps of enzymes

•III) oxidative catabolism in the mitochondrial matrix

•Within the matrix, the acetyl-COA goes through the process of kreb cycle and generating NADH, FADH2 which are used in ETC

Lipase

Enzyme that hydrolyzes triglycerides.

Glycerol

Converted to glucose via glycolysis.

Fatty Acid Transporter

Facilitates fatty acid entry into cells.

Protein Metabolism

Involves amino acids for various bodily functions.

•Of the 20 amino acids in our bodies, 10 are referred to as essential amino acids. These amino acids cannot be synthesized by the human body from molecules present within the body. They are synthesized by plants or bacteria. Food containing these amino acids are “essential” for human growth and must be a part of the diet.

Polypeptide Chain

Long chain of amino acids.

Steps involved in protein metabolism

•1) Amino acids go through the process of transamination, which means you are transferring the amine group from the amino acid to another molecule and forming glutamate via an enzyme called amino transferase

•2) Deamination: glutamate is converted to alpha-ketoglutrate releasing ammonia which is a toxic substance

•3) urea cycle: ammonia is converted to urea through the urea cycle and excreted out via urine

Glycogenesis

Storage of glucose as glycogen.

Glycogenolysis

Release of glucose from glycogen.

Lipogenesis

Synthesis of fatty acids from excess carbohydrates.

Gluconeogenesis

Conversion of proteins or fats into glucose.

•Nervous tissue/RBC need glucose as a source oof energy so proteins and fat are converted to glucose via gluconeogenesis

•Reaction process:

•Glycolysis: pyruvic acid is converted eventually back to glucose

•Kreb Cycle: oxaloactetate is used to help the conversion to fructose 1-6 bis phosphate

•Other ways: lactic acid back to pyruvate

Absorptive State

Nutrient absorption period after meals.

•Starts approx. 4 hours after eating

•the body spends about 12 hours of each day in the absorptive state.

•Excess Glucose transported to the liver is converted to glycogen

•Amino acids in liver cells are converted to carbohydrates, fats, and proteins.

•Most dietary lipids are stored in adipose tissue.

Postabsorptive State

Maintains blood glucose levels after nutrient absorption.

•12 hours, during late morning, late afternoon, and most of the evening, are spent in the postabsorptive state.)

•fatty acids from fat tissue fed into Krebs as acetyl CoA

•lactic acid produced anaerobically during exercise

•Red blood cells

•derive all of their ATP from glycolysis of glucose by anaerobic respiration because they lack mitochondria (and thus lack the Krebs cycle and electron transport chain.)

Core Temperature

Body temperature in structures below skin.

Shell Temperature

Body temperature at skin surface.

•that is, the skin and subcutaneous tissue.

•shell temperature is usually 1 to 6 degrees lower

•Too high a core temperature kills the organism by

•denaturing body proteins

•Too low a core temperature kills by

•cardiac arrhythmias: irregular heartbeat

Heat Production

Balance with heat loss maintains body temperature.

Two centers in the hypothalamus related to regulation of food intake

•feeding (hunger) center and satiety center. The feeding center is constantly active but may be inhibited by the satiety center

•The hormone leptin

•It acts on the hypothalamus to inhibit ciruits that stimulate hunger & eating and to activate circuits that increase energy expenditure.

Minerals: calcium/ phosphorous

•form part of the matrix of bone

•help regulate enzymatic reactions

•calcium, iron, magnesium

Mg

•is catalyst for conversion of ADP to ATP

•regulate osmosis of water

•generation of nerve impulses

Fat-soluble vitamins

•emulsified into micelles and absorbed along with ingested dietary fats by the small intestine. They are stored in cells (particularly liver cells) and include vitamins A, D, E, and K.

Water-soluble vitamins

•absorbed along with water in the GI tract and dissolve in the body fluids. Excess quantities of these vitamins are excreted in the urine. The body does not store water-soluble vitamins well. They include the B vitamins and vitamin C.