Biology: Carbohydrates and Biomolecules

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Questions and Answers

What percentage of monosaccharides exist in the open-chain form?

Less than 1% (correct)

Around 50%

About 10%

More than 90%

Which component is formed when a monosaccharide cyclizes?

An anomeric carbon (correct)

A reducing sugar

A polymer

A glycosidic bond

What is the structure of sucrose?

β-fructose + β-galactose

β-galactose + α-glucose

α-glucose + β-fructose (correct)

α-glucose + α-glucose

Which type of bond forms between monosaccharides to create disaccharides?

Glycosidic bonds Signup and view all the answers

What configuration does the anomeric hydroxyl take in an α-bond?

α configuration Signup and view all the answers

Which of the following is categorized as a reducing sugar?

Lactose Signup and view all the answers

Which compound is involved in forming a glycosidic bond during polymerization of sugars?

Glycosyltransferases Signup and view all the answers

What is a key characteristic of reducing sugars in terms of their functional groups?

They all contain carbonyl groups. Signup and view all the answers

What is the empirical formula for many simpler carbohydrates?

(CH2O)n Signup and view all the answers

Which of the following statements correctly describes epimers?

They are carbohydrate isomers that differ at only one specific carbon atom. Signup and view all the answers

Which of the following is NOT a classification of monosaccharides based on the number of carbon atoms?

Maltose Signup and view all the answers

How are monosaccharides numbered?

From the carbonyl carbon towards the other end. Signup and view all the answers

Which sugar is NOT considered a D-sugar?

L-Sugar Signup and view all the answers

Which functional group determines if a monosaccharide is an aldose or ketose?

Carbonyl carbon (C=O) Signup and view all the answers

Which of the following sugars are isomers?

Galactose, Fructose, and Glucose Signup and view all the answers

Which characteristic is true of carbohydrates?

They can be structural components of many organisms. Signup and view all the answers

What is the primary storage form of glucose in animals?

Glycogen Signup and view all the answers

Which type of glycosidic bond primarily connects glucose units in cellulose?

β1-4 glycosidic bonds Signup and view all the answers

What are the key structural features of starch?

Composed of amylose and amylopectin with both α1-4 and α1-6 bonds Signup and view all the answers

Which of these best describes the bonding in glycogen?

Contains α1-6 bonds and ~10 α1-4 bonds with frequent branching Signup and view all the answers

What is the role of ribose in biological systems?

It forms components of nucleotides and nucleic acids. Signup and view all the answers

How does cellulose differ structurally from starch?

Cellulose is made of β glucose, while starch is made of α glucose. Signup and view all the answers

What is the significance of glycoproteins in biological systems?

They are involved in cellular signaling and immune responses. Signup and view all the answers

What type of bond is formed when a sugar is attached to a purine base?

N-glycosidic link Signup and view all the answers

What is a key feature of glycogen regarding its structure?

It is highly branched, with branching occurring every ~10 glucose units. Signup and view all the answers

What role does glucose play in the human body?

It serves as the main energy source in all cells. Signup and view all the answers

Study Notes

Carbohydrates

Carbohydrates are the most abundant organic molecules in nature
They are classified based on the number of carbon atoms, sugar subunits, or functional groups
Carbohydrates exist as isomers, which have the same chemical formula but different structures
Carbohydrates' functions include short-term energy generation, intermediate-term energy storage, and structural components of cells
Carbohydrates can be attached to non-carbohydrate molecules by glycosidic bonds

Biomolecules

Biomolecules are organic molecules formed by living organisms
They are primarily composed of carbon, hydrogen, oxygen, and nitrogen
Four major classes of biomolecules include carbohydrates, proteins, lipids, and nucleic acids

Monosaccharides

Monosaccharides are simple sugars that cannot be hydrolyzed into simpler carbohydrates
They are classified based on the number of carbon atoms (e.g., trioses, tetroses, pentoses, hexoses)
Monosaccharides can be aldoses (aldehyde functional group) or ketoses (ketone functional group)
Common monosaccharides include glucose, fructose, and galactose

Isomers

Isomers have the same chemical formula but different structures
Examples include glucose, galactose, and fructose, all with the formula C₆H₁₂O₆.
Enantiomers are nonsuperimposable mirror images

Epimers

Epimers are isomers that differ in the configuration around only one specific carbon atom (excluding the carbonyl carbon)
Glucose and mannose are C-2 epimers
Glucose and galactose are C-4 epimers

Cyclisation

Monosaccharides often exist in ring formations
Less than 1% of monosaccharides exist in their open-chain form
Cyclization creates an anomeric carbon

Glycosidic bonds

Glycosidic bonds are the bonds that link monosaccharides to form disaccharides, oligosaccharides, and polysaccharides
They are formed through dehydration reactions (condensation)
Glycosidic bonds are named based on the configuration of the anomeric hydroxyl group (α or β)

Common disaccharides

Disaccharides are formed from two monosaccharides
Examples include lactose (β-galactose + α-glucose), maltose (α-glucose + α-glucose), and sucrose (α-glucose + β-fructose)

Reducing sugars

Reducing sugars can act as reducing agents because the anomeric carbon is not involved in a glycosidic bond
All monosaccharides are reducing sugars

Glucose – biomedical importance

Glucose is a crucial energy source in all cells
It cannot be stored in this form because it would affect osmotic balance
It is stored as glycogen in animals
Ribose is present in nucleotides and nucleic acids.

Polymers of glucose

Glycogen: Storage form of glucose in animals, highly branched
Starch: Storage form of glucose in plants; composed of amylose (linear) and amylopectin (branched)
Cellulose: Structural component of plant cell walls, composed of unbranched chains of β-glucose

Cellulose vs Starch

The main difference between cellulose and starch is that cellulose uses β-glucose while starch uses α-glucose units in its structure

Complex carbohydrates

Carbohydrates can be attached to non-carbohydrate molecules via glycosidic bonds
Structures include glycoproteins, proteoglycans, and glycolipids
The types of glycosidic bonds depend on the attached non-carbohydrate molecule (-NH₂ group = N-glycoside, -OH group = O-glycoside)

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Description

Explore the fascinating world of carbohydrates and biomolecules in this quiz. Learn about the classification, functions, and structures of carbohydrates, as well as the four major classes of biomolecules. Test your knowledge of monosaccharides, isomers, and their roles in living organisms.