Nucleic Acids

What is the overarching term for all the biochemical reactions involved in maintaining the dynamic state of the cell?

Metabolism

What are the products and substrates in metabolic reactions referred to as?

Intermediates or metabolites

What is another term for intermediates in metabolic reactions?

Metabolites

Metabolism and the reactions involved are classified into catabolism and which other process?

Anabolism

Which process is the breakdown of molecules to produce energy?

Catabolism

Catabolism is characterized as what kind of reactions?

Degradative reactions

Which process is the synthesis of molecules that consume energy?

Anabolism

Anabolism is characterized as what kind of reactions?

Synthetic reaction

What are consecutive biochemical/metabolic reactions called?

Pathways

What kind of pathways lead to the production of energy?

Catabolic pathways

What kind of pathways lead to the synthesis of biomolecules?

Anabolic pathways

Carbohydrate digestion begins in the mouth with what process?

Mastication

Food is turned into what upon entering the esophagus?

Bolus

What enzyme is present in the mouth that begins carbohydrate digestion?

Salivary amylases

Salivary amylases hydrolyze alpha-glycosidic linkages in starch and glycogen to produce what two products?

Smaller polysaccharides and disaccharide – maltose

Why is there minimal absorption in the mouth?

Food is swallowed quickly

In the stomach, what enzyme is inactivated?

Salivary amylase

Why is salivary amylase inactivated in the stomach?

Because of hydrochloric acid (HCl) in the stomach acidity

In the stomach, what is the bolus turned into?

Chyme

What absorption takes place in the stomach?

Amino acid absorption

Once food enters the small intestine, what is released that neutralizes the pH?

Bile

What is the primary function of bile besides pH neutralization?

Emulsify lipids

What enzyme breaks down polysaccharide chains into the disaccharide maltose in the small intestine?

Pancreatic alpha-amylase

What is the site of digestion due to the presence of pancreatic amylase?

Small Intestine

Where does most of the absorption occur?

Small and large intestines

Which enzyme converts maltose to glucose on the outer membrane of intestinal mucosal cells?

Maltase

Which enzyme converts sucrose to glucose and fructose?

Sucrase

Which enzyme converts lactose to glucose and galactose?

Lactase

What are the carbohydrate digestion products absorbed into the bloodstream?

Glucose, galactose, and fructose

What are the monosaccharides actively transported into?

Blood capillaries

What mediates the passage of the monosaccharides through cell membranes?

Protein carriers

Galactose and fructose are converted to products of glucose metabolism in what organ?

Liver

What are the end products of carbohydrate digestion, which are single sugar units?

Monosaccharides (glu, gal, fruc)

What is the term for the breakdown of glucose?

Glycolysis

Where does glycolysis take place within the cell?

Cytoplasm

Which molecule is converted to two molecules of pyruvate?

One molecule of glucose

Glycolysis produces what two key energy molecules?

ATP and NADH

What are the two stages in which glycolysis occurs?

Six-carbon (Energy Investment) and three-carbon (Energy Production/Payoff) stages

The six-carbon stage is also known as what?

Energy Investment

The three-carbon stage is also known as what?

Energy Production/Payoff

What are irreversible reactions in metabolic pathways known as?

Committed steps

Committed steps usually involve the addition/removal of what two groups?

Phosphate groups or CoA

Which enzyme class transfers a phosphoryl group?

Kinase

Which enzyme class converts a ketose into an aldose or vice versa?

Isomerase

Which enzyme class shifts a phosphoryl group within a molecule?

Mutase

Redox reactions between the intermediate and another molecule (like NADH or FADH2) are catalyzed by which enzyme class?

Dehydrogenase

What is the reaction in Step 1?

Phosphorylation of glucose

Which enzyme catalyzes Step 1?

Hexokinase

What is the energy required for Step 1 derived from?

ATP hydrolysis

Which enzyme isomerizes glucose 6-phosphate to fructose 6-phosphate in Step 2?

Phosphoglucoisomerase

Step 3 is which type of reaction?

Phosphorylation reaction

Which enzyme is involved in Step 3?

Phosphofructokinase

In Step 4, what C6 biphosphate is split?

Fructose 1,6-bisphosphate

What are the two C3 monophosphate species formed in Step 4?

Dihydroxyacetone phosphate and glyceraldehyde 3-phosphate

Which enzyme catalyzes Step 4?

Aldolase

In Step 5, what molecule is isomerized to glyceraldehyde 3-phosphate?

Dihydroxyacetone phosphate

Which enzyme is involved in Step 5?

Triosephosphate isomerase

Which enzyme catalyzes Step 6?

Glyceraldehyde 3-phosphate dehydrogenase

How many molecules of NADH are produced in Step 6?

2 molecules of the reduced coenzyme NADH

What is the source of the added phosphate in Step 6?

Inorganic phosphate (Pi)

Step 7 is what kind of ATP-producing step?

An ATP-producing step

What is the process in Step 7 called?

Substrate-level phosphorylation

Which enzyme is involved in Step 7?

Phosphoglycerokinase

Step 8 involves the isomerization of 3-phosphoglycerate to what?

2-phosphoglycerate

Which enzyme is involved in Step 8?

Phosphoglyceromutase

What type of reaction is Step 9?

Alcohol dehydration reaction

Which enzyme is involved in Step 9?

Enolase

What is the final product of glycolysis in Step 10?

Pyruvate

Which enzyme is involved in Step 10?

Pyruvate kinase

The overall equation for glycolysis produces how many ATP?

2 ATP

The overall equation for glycolysis consumes how many ADP?

2 ADP

The overall equation for glycolysis consumes how many Pi?

2 Pi

What are the two products besides pyruvate, NADH, ATP, and H+?

2 H2O

Besides glucose, which three simple sugars can enter the glycolytic pathway?

Fructose, Galactose, Mannose

Hexokinase (Step 1) is inhibited by what molecule?

Glucose 6-phosphate (feedback inhibition)

Phosphofructokinase (Step 3) is inhibited by high concentrations of what two molecules?

ATP and citrate

Pyruvate kinase (Step 10) is inhibited by what molecule?

High ATP concentrations

Both pyruvate kinase and phosphofructokinase are what type of enzymes?

Allosteric enzymes

Pyruvate is metabolized in one of three ways depending on what?

Type of organism and the presence or absence of O2

Pyruvate metabolism provides a continuous supply of what for glycolysis?

NAD+

Oxidation to Acetyl-CoA takes place under what conditions?

Aerobic (oxygen-rich) conditions

Oxidation to Acetyl-CoA is catalyzed by what?

Pyruvate dehydrogenase complex

Pyruvate enters which part of the cell for oxidation?

Mitochondrial matrix

Acetyl-CoA molecules enter what process?

Citric acid cycle

Fermentation processes occur under what condition?

Anaerobic (oxygen-deficient) conditions

Lactate Fermentation takes place in which tissue?

Muscles

Lactate Fermentation is catalyzed by which enzyme?

Lactate dehydrogenase

Lactate fermentation increases the concentration of what two substances in muscle tissue?

Lactate and H+

What does Lactate Fermentation provide for glycolysis?

NAD+

Lactate is converted back to pyruvate when what is reestablished?

Aerobic conditions

Ethanol Fermentation takes place in what types of organisms?

Simple organisms, e.g. yeast, bacteria

Which two enzymes catalyze the two-step Ethanol Fermentation process?

Pyruvate decarboxylase and alcohol dehydrogenase

Ethanol fermentation produces NAD+, ethanol and what gas?

CO2

What is the pathway by which glucose is synthesized from noncarbohydrate materials?

Gluconeogenesis

Which process is described as not being the exact opposite of gluconeogenesis?

Glycolysis

Besides pyruvate, what non-carbohydrate starting materials for gluconeogenesis come from triacylglycerol hydrolysis?

Glycerol

Which non-carbohydrate starting materials for gluconeogenesis come from dietary or muscle protein hydrolysis?

Glucogenic amino acids

Lactate, a starting material for gluconeogenesis, is sourced from which two locations?

Muscles and red blood cells

About what percentage of gluconeogenesis takes place in the liver?

90%

Which depleted stores does gluconeogenesis replenish?

Liver glycogen stores