Biochemistry: Structure of Carbohydrates

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Questions and Answers

What is the primary function of D-Ribose in the human body?

Structural support

Energy storage

Nucleic acid formation (correct)

Intercellular communication

Which of the following monosaccharides is NOT linked by glycosidic bonds?

D-Lyxose (correct)

D-Glucose

D-Ribose

D-Fructose

What is the consequence of a failure to metabolize D-Galactose in the body?

Histamine release

Galactosemia (correct)

Insulin resistance

Hemolytic anemia

Which sugar acid is specifically produced by the oxidation of the hydroxyl carbon?

D-Galactose Signup and view all the answers

What role do glycosyltransferases play in carbohydrate biochemistry?

Forming glycosidic linkages Signup and view all the answers

What is the major polysaccharide found in the shells of insects and crustaceans?

Chitin Signup and view all the answers

What happens to D-Fructose in the liver after its consumption?

It is converted to glucose Signup and view all the answers

Which of the following carbohydrates is a key structural component in bacterial cell walls?

Chitin Signup and view all the answers

What is the initial step in the metabolism of sugars?

Phosphorylation Signup and view all the answers

Which carbohydrate is used primarily by muscles for ATP generation during contraction?

Muscle glycogen Signup and view all the answers

Which sugar is a deoxy sugar that is crucial for DNA?

2-deoxyribose Signup and view all the answers

Which of the following compounds is NOT classified as an epimer?

Fructose Signup and view all the answers

What role does glucuronic acid play in metabolism?

It is involved in bilirubin metabolism. Signup and view all the answers

Which carbohydrates are examples of sugar alcohols?

Ribose and Xylitol Signup and view all the answers

Which carbohydrate structure is primarily made of amylose and amylopectin?

Starch Signup and view all the answers

Which of the following accurately describes isomers?

Compounds that have the same chemical formula but different structures. Signup and view all the answers

Which term refers to stereoisomers that differ only at one asymmetric carbon?

Epimers Signup and view all the answers

What is the common chemical formula of fructose, glucose, mannose, and galactose?

C6H12O6 Signup and view all the answers

Which statement about sugar alcohols is correct?

They are monosaccharides reduced at the carbonyl carbon. Signup and view all the answers

Which of the following options is NOT a component of proteoglycans?

Ascorbic Acid Signup and view all the answers

What term describes carbohydrates that are connected to non-carbohydrate structures?

Complex carbohydrates Signup and view all the answers

Which statement correctly describes the characteristic of D-sugars in humans?

D-sugars are the majority of sugars found in humans. Signup and view all the answers

Which of the following correctly defines racemases?

They are enzymes that interconvert D- and L- isomers. Signup and view all the answers

What does the term 'enantiomers' refer to?

Isomers that are mirror images of one another. Signup and view all the answers

What does dextrorotatory (D) indicate in terms of polarized light?

The light is rotated clockwise. Signup and view all the answers

What represents the main difference between N-glycoside and O-glycoside structures?

N-glycosides attach the -NH2 group; O-glycosides attach the -OH group. Signup and view all the answers

Which of the following is true about the classification of sugars?

All sugars are either D-sugars or L-sugars. Signup and view all the answers

What primarily distinguishes complex carbohydrates from simple carbohydrates?

Complex carbohydrates are linked to non-carbohydrate structures. Signup and view all the answers

Which of the following accurately reflects the relationship between D-sugars and their ability to rotate light?

Most D-sugars are classified as dextrorotatory. Signup and view all the answers

Which of the following best describes the functional nature of glycosaminoglycans?

They serve as lubricants and structural elements in tissues. Signup and view all the answers

What distinguishes aldoses from ketoses in carbohydrates?

Aldoses have an aldehyde as their most oxidized functional group. Signup and view all the answers

Which statement about disaccharides is true?

They are formed from two monosaccharides. Signup and view all the answers

Which of the following carbon counts represents a pentose?

5 Signup and view all the answers

Which of the following groups can be found in carbohydrates besides hydroxyl groups?

Phosphate groups Signup and view all the answers

What is a characteristic feature of polysaccharides?

They consist of more than 10 monosaccharides. Signup and view all the answers

Which of the following is an example of a hexose?

Glucose Signup and view all the answers

What is the primary characteristic of triodes in carbohydrate classification?

They consist of 3 carbon atoms. Signup and view all the answers

What common feature do glycosaminoglycans share?

They contain sulfate groups. Signup and view all the answers

Which of the following substances is classified as a nonose?

Neuraminic acid Signup and view all the answers

What type of functional group is typically associated with ketoses?

Keto groups Signup and view all the answers

Study Notes

Overview of Carbohydrates

Carbohydrates are the most abundant organic molecules in nature.
Exist as polyhydroxylated aldehydes or ketones.
Minimum structure requires at least three carbon atoms, a hydroxyl group, and typically an aldehyde or ketone.
Classified into monosaccharides, disaccharides (two monosaccharides), oligosaccharides (three to ten monosaccharides), and polysaccharides (more than ten monosaccharides).

Types of Monosaccharides

Triose: Glyceraldehyde (3 carbons)
Tetroses: Erythrose (4 carbons)
Pentoses: Include Ribose (5 carbons), vital for nucleic acids and as a coenzyme.
Hexoses: Include Glucose (6 carbons), primary energy source; important for metabolism.
Heptoses: Sedoheptulose (7 carbons).
Nonoses: Neuraminic acid (9 carbons), important in cell recognition.

Key Functional Groups

Can contain phosphate (e.g., UDP-glucose), amino (e.g., Glucosamine), or sulfate groups (e.g., Chondroitin sulfate).
Aldoses have an aldehyde group (e.g., Glyceraldehyde).
Ketoses have a keto group (e.g., Dihydroxyacetone).

Functions of Carbohydrates

Provide energy and are storage forms (glycogen).
Act as metabolic intermediates and form components of nucleotides in DNA and RNA.
Contribute to cell membranes, immunity, and structural roles in organisms, such as cellulose in plants and chitin in shells.

Sugar Metabolism and Important Compounds

Monosaccharides linked by glycosidic bonds.
Initial step in sugar metabolism is phosphorylation.
Glucosamine is derived from chitin, significant in insect shells.
Galactosamine is found in polysaccharides such as cartilage.

Glycogen and Energy Storage

Glycogen serves as the primary storage carbohydrate in animals, mainly in liver and muscle.
Liver glycogen maintains blood glucose levels during fasting; muscle glycogen helps generate ATP for contraction.

Sugar Acids and Their Role

Produced from oxidation of specific carbons (e.g., Ascorbic Acid and Glucuronic Acid).
Glucuronic Acid is vital in proteoglycans and bilirubin metabolism.

Unique Sugars and Isomerism

Deoxy sugars have a hydrogen atom instead of a hydroxyl group (e.g., 2-deoxyribose).
Sugar alcohols result from the reduction of carbonyls in monosaccharides.
Isomers have identical molecular formulas but different structures (e.g., Fructose, Glucose).
Epimers differ at one asymmetric carbon (e.g., Glucose and Galactose are C-4 epimers).

Enantiomers and Their Importance

Enantiomers are mirror-image isomers, defined as D- and L- sugars based on light polarization direction.
D-sugars dominate in human biochemistry, with enzymes (racemases) facilitating interconversion.

Complex Carbohydrates

Complex carbohydrates link to non-carbohydrate structures, such as nucleotides and glycoproteins.
N-glycosidic bonds connect amino groups of non-carbohydrates to sugars.
O-glycosidic bonds link hydroxyl groups of non-carbohydrates to sugars.

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Description

Explore the intriguing world of carbohydrates in biochemistry. This quiz delves into different types of carbohydrates, their structures, and examples across various carbon counts. Test your knowledge on trioses, tetroses, and more!