CARBOHYDRATE METABOLISM

digestion

is the biochemical process by which food molecules, through hydrolysis, are broken down into simpler chemical units that can be used by cells for their metabolic needs.

pancreatic a-amylase

breaks down polysaccharide chains into shorter and shorter segments until the disaccharide maltose

maltase, sucrase, and lactase

important disaccharidase enzymes are

glucose, galactose, and fructose

major breakdown products from carbohydrate digestion are thus

intestinal mucosa

enzyme sucrase is active

small intestine

hydrolysis reactions converting polysaccharides to disaccharides occur

mouth

First site where breaking of glycosidic linkages occurs

intestinal mucosa

The monosaccharides glucose, fructose, and galactose are produced.

small intestine

Pancreatic enzymes are active

intestinal mucosa

Hydrolysis reactions converting disaccharides to monosaccharides occur.

intestinal lining villi

Monosaccharides enter the bloodstream.

small intestine

primary site for carbohydrate digestion is located here.

glycolysis

is the metabolic pathway by which glucose (a C6 molecule) is converted into two molecules of pyruvate (a C, molecule), chemical energy in the form of ATP is produced, and NADH-reduced coenzymes are produced.

hexokinase

Step 1. Phosphorylation Using ATP: Formation of Glucose 6-Phosphate.

phosphoglucoisomerase

Step 2. Isomerization: Formation of Fructose 6-Phosphate.

phosphoructokinase

Step 3; Phosphorylation Using ATP: Formation of Fructose 1,6-Bisphosphate.

aldolase

Step 4. Cleavage; Formstion of Two Triose Phosphate

triose phosphate isomerase

Step 5: Isomerization: Formation of Glyceraldehyde 3-Phosphate

glyceraldehyde 3-phosphate dehydrogenase

Step 6. Oxidation and Phosphorylation Using P1; Formation of 1,3-Bisphosphoglycerate

phosphoglycerokinase

Step 7. Phosphorylation of ADP: Formation of 3-Phosphoglycerate

substrate-level phosphorylation

is the biochemical process whereby ATP is produced from ADP through direct transfer of a high-energy phosphoryl group from a reaction substrate to ADP

phosphoglyceromutase

Step 8: Isomerization; Formation of 2- Phosphoglycerate

enolase

Step 9: Dehydration: Formation of Phosphoenolpyruvate

pyruvate kinase

Step 10: Phosphorylation of ADP; Formation of pyruvate

steps 1,3, 7 and 10

ATP molecules involved

step 6, 9

energy rich compound is formed in what steps

steps 7, 10

ATP formed from ADP

-1

step 1; glucose to glucose 6-phosphate

-1

step 3; fructose 6-phosphate to fructose 1,6- biphosphate

+2

Step 7; 2(q,3- Biphosphoglycerate to 3- phosphogylcerate

+2

Step 10; 2(Phosphoenolpyruvate- pyruvate)

C6, one phosphate

glucose 6-phosphate

C6, two phosphate

fructose 1,6- biphosphate

C3, one phosphate

Glyceraldehyde 3-phosphate

C3, one phosphate

3- phosphoglycerate

step 7

fist phosphorylation of ADP occurs

step 6

first energy rich compound is produced

step 9-10

second energy rich compound undergoes reaction

step 2

first isomerization occurs

steps 2,5,8

steps that undergoes isomerizarion

step 10

second formation of ATP occurs

step 9

second energy rich compound is produced

step 3

ATP is converted for the second time

step 9

a dehydration reaction occurs

step 3

phosphofructokinase

step 8

phosphoglyceromutase

step 5

triose phosphateisomerase

step 9

enolase

step 1

hexokinase

step 10

pyruvate kinase

step 6

Glyceraldehyde 3- phosphate dehydrogenase

step 7

phosphoglycerokinase

glyceraldehyde and dihydroxyacetone phosphate

The entry of fructose into the glycolytic pathway involves phosphorylation by ATP to produce fructose 1-phosphate, which is then split into two trioses— ___.

dihydroxyacetone phosphate

enters glycolysis directly

glyceraldehyde 3-phosphate

glyceraldehyde must be phosphorylated by ATP to ____ before it enters the pathway

steps 1, 3, 10

steps that undergoes glycolysis

allosteric enzyme

pyruvate kinase, phosphofructokinase

conversion to acetyl CoA, conversion to lactate, and conversion to ethanol

Three common fates for pyruvate, all of importance, exist

acetyl CoA formation

requires aerobic (oxygen-rich) conditions

lactate and ethanol formation

occur under anaerobic (oxygen-deficient) conditions

ethanol formation

is limited to some microorganisms

gluconeogenesis

additional fate for pyruvate is conversion to oxaloacetate. This tate for pyruvate, which occurs during the process called

pyruvate

the end product of glycolysis, can leave the cytosol, cross the two mitochondrial membranes, and enter the mitochondrial matrix.

cytosol, mitochondrial matrix

pyruvate is formed through glycolysis crosses the two mitochondrial and enter __ where oxidation takes place

fermentation

is a biochemical process by which NADH is oxidized to NAD+without the need for oxygen

lactate fermentation and ethanol fermentation

Two fermentation processes

lactate fermentation

is the enzymatic anaerobic reduction of pyruvate to lactate.

lactate, pyruvate, and glycerate

are all derivatives of propionic acid, the three-carbon unsaturated monocarboxylic acid

red blood cells

have no mitochondria and therefore always form lactate as the end of glycolysis

ethanol fermentation

is the enzymatic anaerobic conversion of pruvate to ethanol and carbon dioxide. It sim involving yeast causes bread and related products to rise as a result of CO2

step 6

Anaerobic lactate formation allows for "recycling" of NAD*, providing the NAD+ needed for ___ of glycolysis.

lactate accumulation and pH change

are the cause of muscle pain and cramping during prolonged, strenuous exercise

heart muscle

Lactate accumulation can also occur in ___ if it experiences decreased oxygen supply (from artery block-age).

rapid breathing (hyperventilation)

raises slightly the pH of blood; which makes it basic

bicarbonate (HCO33)

solution to counteract the acidity change in the blood that accompanies lactate buildup.

acetaldehyde

first step in conversion of pyruvate to ethanol is a decarboxylation reaction to produce

ethanol

second step involves acetaldehyde reduction to produce

lactate fermentation

CO2 is not a product for this pathway

lactate fermentation

C3 molecule is a product for this pathway

acetyl CoA formation

NAD+ is needed as an oxidizing agent for this pathway

alcohol fermentation

C2 molecule is a product under anaerobic reaction conditions for this pathway

ethanol fermentation

Acetaldehyde is an intermediate in this pathway

ethanol fermentation

This is an anaerobic pathway that does not function in humans.

lactate fermentation

This is an anaerobic pathway that does function in humans.

acetyl CoA formation

C2 molecule is a product under aerobic reaction conditions for this pathway

complete oxidation of glucose

using assembled energy production figures for glycolysis, oxidation of pyruvate to acetyl CoA, the citric acid cycle, and the electron transport chain- with one added piece of information give the ATP yield for ____

cytosolic reduction

first step in the shuttle is the ____ of dihydroxyacetone phosphate by NADH to produce glycerol 3-phosphate and NAD+

FAD

oxidizing agent in the complete oxidation

+2

yield of ATP: 2 (succinylcholine CoA to succinate)

+3

yield atp: 2 Cytosolic NADH formed in glycolysis

+5

yield atp: 2 NADH formed in the oxidation of pyruvate

+3

2 FADH2 formed in the citric acid cycle

+15

6 NADH formed in the citric acid cycle

2 cytosolic NADH formed in glycolysis

2 FADH2 formed in the citric acid cycle

each produces 1.5 ATP

2 NADH formed in the oxidation of pyruvate

6 NADH formed in the citric acid cycle

each produces 2.5 ATP

30 ATP

ATP production for complete oxidation of a molecule of glucose

26

come from the oxidative phosphorylation associated with the ETC

2 ATP

for oxidation of glucose to lactate and ___ for oxidation of glucose to ethanol.

glycogen

branched polymeric form of glucose is the storage of carbohydrates in humans and animals

glycogen

in the liver, it is the source of glucose needed to maintain normal glucose levels in the blood