BIOCHEM EXAM 2

Carbohydrates

Biomolecules that serve as a primary source of energy, structural components, and signaling molecules in cells.

Glycogen

A polysaccharide made of glucose units, used for energy storage in animals.

Monosaccharide

The simplest form of carbohydrates, consisting of a single sugar unit (e.g., glucose, fructose).

Disaccharide

A carbohydrate formed from two monosaccharides linked by glycosidic bonds (e.g., sucrose, lactose).

Polysaccharide

A carbohydrate composed of long chains of monosaccharide units (e.g., starch, cellulose).

Glycoprotein

A protein with carbohydrate chains attached, involved in cell recognition and signaling.

Lactase

An enzyme that catalyzes the hydrolysis of lactose into glucose and galactose.

Lactose intolerance

A condition resulting from the deficiency of lactase, causing symptoms after dairy consumption.

ATP

A high-energy molecule used as an energy currency in cells.

Catabolism

The metabolic process of breaking down larger molecules into smaller ones, releasing energy.

Anabolism

The metabolic process of building larger molecules from smaller ones, requiring energy.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, producing ATP in the process.

Oxidation

The loss of electrons by a molecule; often linked to energy release.

Reduction

The gain of electrons by a molecule; often associated with energy storage.

Metabolic pathway

A series of chemical reactions in a cell that convert substrates into products through enzyme action.

Enzyme regulation

The mechanisms that control enzyme activity and function to maintain metabolic balance.

Flux

The rate at which metabolites flow through a metabolic pathway, influenced by various factors.

ΔG (Gibbs Free Energy)

A thermodynamic quantity that indicates the spontaneity of a reaction; negative ΔG indicates a spontaneous reaction.

Pentose Phosphate Pathway

A metabolic pathway that generates ribose for nucleic acid synthesis and NADPH for biosynthetic reactions.

Homeostasis

The ability of a cell or organism to maintain stable internal conditions.

D-Fructose

Ketose

D-galactose

Aldose

D-glucose

Aldose

D-Mannose

Aldose

D-ribose

Aldose

Name

Glycogen

Monosaccharide

Glucose

Linkage

a-1,4-glycosidic bonds linked by a-1,6-glycosidic bond forms every 12 glucose units

Name of enzyme to breakdown

a-amylase, glycogen phosphorylase

Cellulose

Name

Glucose

Monosaccharide

Beta-1, 4-glycosidic bonds

Linkage

Cellulase

Name of enzyme to breakdown

Starch (amylose)

Name

Glucose

Monosaccharide

a-1,4-glucosidic bonds

Linkage

a-amylase

Name of enzyme to breakdown

Glucose-6-phosphate

In glycolysis Glucose becomes what in step 1

Frucotse-6-phosphate

In glycolysis Glucose-6-phosphate becomes what in step 2

Frucotse-1,6-biphosphate

In glycolysis fructose-6-phosphate becomes what in step 3

Glyceraldheyhde-3phosphate and dihydroxyacetone phosphate

In glycolysis fructose-1,6-biphosphate becomes what in step 4

What is glycolysis?

A metabolic pathway that converts glucose into pyruvate, producing a small amount of ATP.

Where does glycolysis occur?

In the cytoplasm of the cell.

What is the first product of glycolysis?

Glucose-6-phosphate.

What enzyme converts glucose to glucose-6-phosphate?

Hexokinase.

What is the primary purpose of glycolysis?

To break down glucose for energy production.

How many ATP molecules are produced in glycolysis?

A net gain of 2 ATP molecules.

What are the end products of glycolysis?

2 molecules of pyruvate, 2 ATP, and 2 NADH.

What is NADH's role in glycolysis?

It acts as an electron carrier, transferring electrons to the electron transport chain.

What happens to pyruvate after glycolysis?

It can be converted into either acetyl-CoA or lactate, depending on oxygen availability.

What is the structure of glycogen?

Glycogen is a branched polysaccharide made up of glucose units.

All mammalian tissue

Glut1 tissue distribution

Liver and pancreatic Beta Cells

Glut2 tissue distribution

All mammalian tissues-pt2

Glut3 tissue distribution

Muscle and fat cells

Glut 4

Small intestine

Glut5

Glut4

Transporter responsible for transporting glucose into muscle and fat cells

Insulin

Molecule that regulates tranpost of GLUT protein to the cell surface in muscle and fat cells

What is gluconeogenesis?

The metabolic process of synthesizing glucose from non-carbohydrate precursors.

Where does gluconeogenesis primarily occur?

In the liver and to a lesser extent in the kidneys.

What are the main substrates for gluconeogenesis?

Lactate, glycerol, and amino acids.

What is the significance of gluconeogenesis?

It maintains blood glucose levels during fasting or intense exercise.

What hormone primarily stimulates gluconeogenesis?

Glucagon promotes gluconeogenesis.

What is the initial substrate for gluconeogenesis?

Pyruvate is often the starting point.

What enzyme catalyzes the conversion of pyruvate to oxaloacetate?

Pyruvate carboxylase.

What role do hormones play in gluconeogenesis?

Hormones like glucagon and cortisol regulate and stimulate gluconeogenesis.

What is the energy requirement for gluconeogenesis?

Gluconeogenesis requires 6 ATP equivalents to synthesize one molecule of glucose.

How does gluconeogenesis differ from glycolysis?

Gluconeogenesis is the reverse of glycolysis but involves distinct enzymes at key steps.

What is glucose-6-phosphate's role in glycolysis?

It is the first product of glycolysis, formed from glucose.

Which enzyme catalyzes the conversion of glucose to glucose-6-phosphate?

Hexokinase.

What is the second step of glycolysis?

Isomerization of glucose-6-phosphate to fructose-6-phosphate.

Which enzyme is responsible for the second step?

Phosphoglucose isomerase.

What is the third step of glycolysis?

Phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate.

Which enzyme catalyzes the third step?

Phosphofructokinase-1 (PFK-1).

What occurs during the fourth step of glycolysis?

Fructose-1,6-bisphosphate is cleaved into two three-carbon molecules: glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.

Which enzyme facilitates the fourth step?

Aldolase.

What is the fifth step of glycolysis?

Isomerization of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate.

What enzyme catalyzes the fifth step in glycolysis?

Triose phosphate isomerase.

What is the first step of glycolysis?

Glucose is phosphorylated to form glucose-6-phosphate.

Which enzyme catalyzes the first step?

Hexokinase or glucokinase.

What is the second step of glycolysis?

Glucose-6-phosphate is isomerized to fructose-6-phosphate.

Which enzyme is responsible for the second step?

Phosphoglucose isomerase.

What is the third step of glycolysis?

Fructose-6-phosphate is phosphorylated to form fructose-1,6-bisphosphate.

Which enzyme catalyzes the third step?

Phosphofructokinase-1 (PFK-1).

What is the fourth step of glycolysis?

Fructose-1,6-bisphosphate is cleaved into two three-carbon molecules.

Which enzyme facilitates the fourth step?

Aldolase.

What are the two products of the fourth step?

Glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.

What is the fifth step of glycolysis?

Dihydroxyacetone phosphate is converted to glyceraldehyde-3-phosphate.

Which enzyme catalyzes the fifth step?

Triose phosphate isomerase.

What is the sixth step of glycolysis?

Glyceraldehyde-3-phosphate is oxidized and phosphorylated to form 1,3-bisphosphoglycerate.

Which enzyme catalyzes the sixth step?

Glyceraldehyde-3-phosphate dehydrogenase.

What is the seventh step of glycolysis?

1,3-bisphosphoglycerate donates a phosphate to ADP to form ATP and is converted to 3-phosphoglycerate.

Which enzyme catalyzes the seventh step?

Phosphoglycerate kinase.

What is the eighth step of glycolysis?

3-phosphoglycerate is converted into 2-phosphoglycerate.

Which enzyme catalyzes the eighth step of glycolysis?

Phosphoglycerate mutase.

What is the ninth step of glycolysis?

2-phosphoglycerate is dehydrated to form phosphoenolpyruvate (PEP).

Which enzyme catalyzes the ninth step of glycolysis?

Enolase.

What is the tenth step of glycolysis?

Phosphoenolpyruvate donates a phosphate to ADP to form ATP and pyruvate.

Which enzyme catalyzes the tenth step of glycolysis?

Pyruvate kinase.

What is the first step of gluconeogenesis?

Conversion of pyruvate to oxaloacetate.