Understanding Carbohydrates and Their Classification

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Questions and Answers

Which enzyme is deficient in von Gierke's disease?

Brancher enzyme

Glucose-6-phosphatase (correct)

Debrancher enzyme

a-1,4-glucosidase

What clinical feature is associated with Pompe's disease?

Hypoglycemia and mental retardation (correct)

Severe fasting hypoglycemia

Progressive liver enlargement

Absence of storage glycogen

What enzyme deficiency characterizes Forbe's disease?

Brancher enzyme

Debrancher enzyme (correct)

Glucose-6-phosphatase

C-Peptide

How much does whole blood glucose decrease per hour at room temperature?

10 mg/dL Signup and view all the answers

What is the plasma glucose concentration at which glucagon and other glycemic factors are released?

65-70 mg/dL Signup and view all the answers

Which type of symptoms are associated with neurogenic/adrenergic hypoglycemia?

Tremors and palpitations Signup and view all the answers

What is the fasting requirement for assessing blood glucose levels?

10-16 hours Signup and view all the answers

Which of the following is a characteristic of Andersen's disease?

Unbranched amylopectin storage Signup and view all the answers

What is a characteristic symptom of Cushing syndrome?

Excessive cortisol Signup and view all the answers

What condition is characterized by glucose intolerance that begins during pregnancy?

Gestational diabetes mellitus Signup and view all the answers

Which laboratory finding would you expect in a state of hyperglycemia?

Ketonemia Signup and view all the answers

What is the fasting plasma glucose threshold indicating provisional diabetes diagnosis?

FPG ≥126 mg/dL Signup and view all the answers

What does the HbA1c measurement assess over a period of about 60 days?

Long-term glucose control Signup and view all the answers

Which method separates glycated proteins based on chemical structure?

Affinity chromatography Signup and view all the answers

In the Nelson Somogyi method, what is the end product produced indicative of glucose measurement?

Arsenomolybdenum blue Signup and view all the answers

What is the primary disadvantage of the Glucose Oxidase Method?

It is inhibited by high concentrations of several substances. Signup and view all the answers

Which reagent is used in the Dubowski method to measure glucose levels in urine and CSF?

Glacial acetic acid Signup and view all the answers

What does the Hexokinase method quantify to determine glucose concentration?

NADH formation Signup and view all the answers

Which hormone is elevated in pheochromocytoma?

Epinephrine Signup and view all the answers

Which ketone body comprises the largest percentage in the body?

β-hydroxybutyric acid Signup and view all the answers

What is indicated by C-peptide levels greater than 1:1 in a patient?

Excessive insulin production Signup and view all the answers

What is the recommended specimen type for ketone measurement in diabetic patients?

Fresh serum or urine Signup and view all the answers

Which of the following is not a cause of increased ketone levels?

Lactose intolerance Signup and view all the answers

What does the Glucose Dehydrogenase Method measure?

NADH generation Signup and view all the answers

What is the recommended situation for measuring ketones in Type 1 Diabetes patients?

During acute illness or stress Signup and view all the answers

Which of the following methods is generally accepted as the reference method for glucose measurement?

Hexokinase Method Signup and view all the answers

What is the general formula for a carbohydrate?

Cx(H2O)y Signup and view all the answers

Which type of carbohydrate has a terminal carbonyl group?

Aldose Signup and view all the answers

Which of the following is a characteristic of reducing sugars?

Can reduce other compounds Signup and view all the answers

What determines the classification of oligosaccharides?

Number of sugar units Signup and view all the answers

Which of the following is an example of a disaccharide?

Maltose Signup and view all the answers

Which carbohydrate classification mainly focuses on whether the compound can exist in non-superimposable forms?

Stereochemistry Signup and view all the answers

Trioses are classified as carbohydrates with how many carbon atoms?

Three Signup and view all the answers

Which of the following carbohydrates yield more than 10 monosaccharides upon hydrolysis?

Polysaccharides Signup and view all the answers

What characteristic defines non-reducing substances?

No free anomeric carbon Signup and view all the answers

Which enzyme is responsible for converting disaccharides to monosaccharides in the intestine?

Maltase Signup and view all the answers

What is a direct end product of glycolysis?

Pyruvic acid Signup and view all the answers

What type of metabolic pathway is glycolysis classified as?

Both aerobic and anaerobic Signup and view all the answers

Which enzyme deficiency is most commonly associated with galactosemia?

Galactose-1-phosphate uridyl transferase Signup and view all the answers

What is a diagnostic indicator of essential fructosuria?

Presence of fructose in urine Signup and view all the answers

What clinical feature is associated with hereditary fructose intolerance?

Irritability and lethargy Signup and view all the answers

What condition occurs due to a defect in fructose-1,6-biphosphate?

Hypoglycemia and lactic acidosis Signup and view all the answers

Study Notes

Carbohydrates

Carbohydrates are compounds containing C, H, and O.
General formula: Cx(H₂O)y
All carbohydrates contain C=O and -OH functional groups.
Derivatives may have additional chemical groups like phosphates, sulfates, and amines.
Models include Fischer and Haworth projections.

Classification of Carbohydrates

Based on the size of the carbon chain:
- Trioses (3 carbons)
- Tetroses (4 carbons)
- Pentoses (5 carbons)
- Hexoses (6 carbons)
Based on the position of the carbonyl group:
- Aldoses (aldehyde group at the end)
- Ketoses (ketone group in the middle)
Based on the number of sugar units:
- Monosaccharides (cannot be broken down further)
- Disaccharides (2 monosaccharides joined)
- Oligosaccharides (2-10 monosaccharides joined)
- Polysaccharides (many monosaccharides joined)
Examples of monosaccharides include glucose, fructose, and galactose.
Examples of disaccharides include maltose, lactose, and sucrose.
Examples of polysaccharides include starch and glycogen.

Chemical Properties of Carbohydrates

Reducing Sugars: Contain a ketone or aldehyde group, with a free anomeric carbon. They can reduce other compounds. Glucose, maltose, fructose, lactose, and galactose are examples.
Non-Reducing Sugars: Do not have a free anomeric carbon or a ketone or aldehyde group. Sucrose (table sugar) is an example.

Major Metabolic Pathways

Glycogenesis: Conversion of glucose to glycogen for storage.
Glycogenolysis: Breakdown of glycogen to glucose.
Hexose Monophosphate Shunt (HMP): Converts glucose-6-phosphate, creating NADPH and pentose phosphates.

Diabetes Mellitus

A group of metabolic diseases characterized by hyperglycemia (high blood sugar).
Glucosuria occurs when plasma glucose exceeds 180 mg/dL.
Ketosis develops with excessive Acetyl-CoA synthesis.
Hyperglycemia results from hormone imbalances.

Types of Diabetes

Type 1 Diabetes (possibly autoimmune and insulin dependent)
Type 2 Diabetes (possibly insulin resistant)
Gestational Diabetes Mellitus (GDM)(occurs during pregnancy)

Criteria and Points of Difference

Detailed information about the types of diabetes based on various medical criteria.

Specimen Collection and Handling

Fasting plasma glucose is typically higher in the morning.
Normal fasting glucose for serum/plasma is 70-110 mg/dL.
Arterial/capillary glucose is about 5 mg/dL higher than venous glucose when fasting.
Urine glucose analysis needs preservative and 4°C storage to prevent loss.
CSF glucose analysis requires centrifugation, 4°C-20°C storage if delayed, and normal CSF glucose is roughly 60-70% of plasma glucose.
The renal threshold for glucose is 180 mg/dL

Glucose Metabolism

Various tests for diagnosing, and long-term control of glucose metabolism are discussed in detail. (Includes various methods of testing blood glucose, and HbA1c)

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Description

This quiz covers the structure and classification of carbohydrates, including their functional groups and various types such as monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Participants will explore the general formulas and models like Fischer and Haworth projections to better understand carbohydrates.