Carbohydrate Metabolism Flashcards by Adrian Molina

Enzyme that breaks down amylose and amylopctin

Amylase

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Amylase will breakdown amylose and amylopectin into?

Dextrin and maltose

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% of starch broken down in the mouth

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mixture of partially digested food and digestive
juices

Chyme

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breaks down dextrin into shorter carbohydrate
chain.

Pancreatic Amylase

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what enzymes?
1. Sucrose → Glucose + Fructose
2. Maltose → Glucose + Glucose
3. Lactose → Glucose + Galactose

Sucrase
Maltase
Lactase

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Once broken down into monosaccharides, compounds
are ready to enter bloodstream via facilitated diffusion &
active transport
1. _____→ fructose
2._____→ glucose and galactose

Facilitated Diffusion
Active Transport

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First organ to receive monosaccharides:

Liver

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Liver converts galactose to?

Glucose

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Liver Stores glucose as?

glycogen

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two metabolic pathways of glucose?

Glycolysis & pentose phosphate pathway

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the process of storing excess glucose
from the bloodstream into the liver and muscles (anabolic)

Glycogenesis

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the process of utilizing the stored
glucose, in response to demand for glucose in certain
tissues (catabolic)

Glycogenolysis

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sourcing carbohydrate from noncarbohydrate compounds by a series of metabolic
pathways; the process that transforms non-carbohydrate
substrates (such as lactate, amino acids, and glycerol) into glucose

Gluconeogenisis

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First stage of glucose metabolism.

GLYCOLYSIS

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glycolysis takes place where?

cytoplasm/cytosol

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two phases of glycolysis

phosphorylation/priming phase
energy yielding phase

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conversion of two molecules glyceraldehyde-3-
phosphate; 2 ATPs are used to prime these reactions

phosphorylation of
glucose/Priming phase

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Formation of
glyceraldehyde-3-phosphate to pyruvate and coupled
formation of 4 molecules of ATP

ENERGY-YIELDING Phase

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In all these reactions, the conversion of glucose to product is

Oxidation Reaction

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when NAD+ is converted to NADH.

reduction or oxidation?

reduction

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Net Reaction: of glycolysis

Glucose + 2ADP + 2Pi → 2 Pyruvate + 2 ATP

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5 steps of priming phase:

Phosphorylation
Isomerization
Phosphorylation
Cleavage
Isomerization

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5 steps of energy yielding phase

Oxidation (and phosphorylation)
Transfer of a phosphate group
Isomerization
Dehydration
Transfer of phosphate group

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reaction involved in step 1: phosphorylation

Glucose + ATP → Glucose-6-phosphate + ADP

reaction involved in step 2: isomerization

Glucose-6-phosphate → Fructose-6-phosphate

reaction involved in step 3: Phosphorylation

Fructose-6-phosphate + ATP → Fructose-1,6-bisphosphate + ADP

reaction involved in step 4: cleavage

Fructose-1,6-bisphosphate → Glyceraldehyde-3-phosphate + Dihydroxyacetone phosphate

reaction involved in step 5: isomerization

Dihydroxyacetone phosphate → Glyceraldehyde-3-phosphate

reaction invloved in step 6: oxidation

Glyceraldehyde-3-phosphate + NAD+ + Pi → NADH + 1,3-bisphosphoglycerate + H+

reaction involved in step 7: transfer of phosphate group

1,3-bisphosphoglycerate + ADP → 3-phosphoglycerate + ATP

reaction involved in step 8: isomerization

3-phosphoglycerate → 2-phosphoglycerate

reaction involved in step 9: Dehydration

2-phosphoglycerate → phosphoenolpyruvate + H2O

reaction involved in step 10: Transfer of phosphate group

Phosphoenolpyruvate + ADP → Pyruvate + ATP

enzymes involved in glycolysis

Hexokinase/Glucokinase Glucose phosphate isomerase Phosphofructokinase Aldolase Triose phosphate isomerase Glyceraldehyde-3-P dehydrogenase Phosphoglycerate kinase Phosphoglyceromutase Enolase Pyruvate Kinase

an NADH-linked dehydrogenase that catalyzes the conversion of pyruvate to lactate

Lactate dehydrogenase

Glucokinase: is found where?

liver

what is hexokinase?

general enzyme that attaches phosphate to any hexose molecule

Possible Fates of Pyruvate in Glycolysis:

Aerobic metabolism: pyruvate loses CO2 then forms acetyl-CoA Anaerobic metabolism: Pyruvate becomes acetaldehyde Fermentation: Acetaldehyde is reduced to ethanol Anaerobic glycolysis: Pyruvate is reduced to lactic acid

pathway of glucose metabolism that is not for the production of energy.

Pentose-Phosphate Pathway

Important for the production of pentoses

Pentose-Phosphate Pathway

important for the production of nicotinamide adenine dinucleotide phosphate (NADPH),

Pentose-Phosphate Pathway

what is nicotinamide adenine dinucleotide phosphate (NADPH)

a coenzyme critical in the biosynthesis of lipids.

what First reaction of Pentose-Phosphate Pathway and its enzyme?

(Glucose-6-phosphate to 6-Phosphogluconate) enzyme: Glucose-6-phosphate dehydrogenase

2nd reaction of (PPT) and its enzyme?

(6-Phosphogluconate to Ribulose-5-phosphate) enzyme: 6-phosphogluconate dehydrogenase

the first and 2nd reactions of PPT are? oxidative or nonoxidative?

oxidative

the remaning reactions of PPT are? oxidative or non oxidative?

nonoxidative

two different reactions in which ribulose-5-phosphate isomerizes are catalyzed by?

phosphopentose-3-epimerase and phosphopentose isomerase

in the reaction that is catalyzed by phosphopentose-3-epimerase; what is produced?

xylulose-5- phosphate,

in the reaction that is catalyzed phosphopentose isomerase; what is produced?

ribose-5-phosphate.

it is a necessary building block for the synthesis of nucleic acids (DNA or RNA) and coenzymes such as NADH.

ribose-5-phosphate.

In PPT what are the Two enzymes that are responsible for the re shuffling of the carbon atoms of sugars such as ribose-5-phosphate and xylulose-5- phosphate in the remainder of the pathway, which consists of three reactions.

tansketolase and transaldolase

Formation of glycogen from excessive glucose in the bloodstream

GLYCOGENESIS

Glycogen synthesis is primed by

glycogenin

Glucose-6-phosphate reacts with UTP to yield?

UDP-glucose

Continuous addition of UDPG to a growing chain. Each step involves formation of a new

α(1→4) glycosidic linkage.

At about 8th residue during glycogenisis what takes over in catalyzing the synthesis of glycogen

glycogen synthase

At about 12th residue, a _______ catalyzes the attachment of a glucose oligosaccharide through an α(1→6) glycosidic linkage.

branching enzyme

the Release of liver glycogen store is triggered by low blood glucose levels.

Glycogenolysis

In the first reaction, each glucose residue cleaved from glycogen reacts with phosphate to give? what is the enzyme?

glucose-1-phosphate. enzyme: Glycogen phosphorylase

In the second reaction, glucose-1-phosphate is isomerized to give? what is the enzyme?

glucose-6-phosphate enzyme: Phosphoglucomutase

Not the reverse of glycolysis

GLUCONEOGENESIS

it is an important intermediate between citric acid cycle (Krebs cycle) and gluconeogenesis

Oxaloacetate

reversible reactions that differs glycolysis and gluconeogenisis

1. Production of pyruvate from phophoenolpyruvate 2. Production of fructose-1,6-bisphosphate from fructose-6-phosphate 3. Production of glucose-6-phosphate from glucose

Why must oxaloacetate be converted to malate?

because oxaloacetate cannot leave the mitochondrion.

before leaving the mitochondrion oxaloacetate reduces to?

malate

Fructose, upon reaching the liver, undergoes

fructolysis.

Galactose, on the other hand, undergoes _____ to become glucose-6-phosphate

leloir pathway

Condition in which blood glucose levels are too high due to absence (or low levels) of insulin or insensitivity to the hormone.

Diabetes Mellitus

Inherited disorder that prevents the processing of galactose, resulting to the build-up of the compound and can cause serious complications in the body.

Galactosemia

Aka Von Gierke’s disease, it affects the ability of the body to release glucose from glycogen stores, with affected people prone to hypoglycemia.

Type I Glycogen Storage Disorder

Rare, inherited, and often fatal disorder that disables heart and skeletal muscles caused by mutations in the gene that produce acid alpha glucosidase, an enzyme similar to a debranching enzyme, but in muscle cells.

Pompe Disease

Carbohydrate Metabolism Flashcards

(72 cards)