Basics of Monosaccharides and Carbohydrates

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Questions and Answers

What contributes to the solubility of glucose and sucrose in water?

The absence of carbonyl groups

The presence of sulfur groups

The presence of hydroxyl (−OH) groups (correct)

The high molecular weight of the sugars

What are the products formed from the hydrolysis of lactose?

D-galactose and D-fructose

D-fructose and D-mannose

D-glucose and D-galactose (correct)

D-glucose and D-mannose

Why is D-glucose’s pentaacetate lacking an aldehyde group?

The aldehyde group is converted during acetylation (correct)

It does not contain any carbon atoms

The aldehyde group is converted into a ketone

It has been completely oxidized

Which of the following compounds is non-soluble in water?

Benzene Signup and view all the answers

How many −OH groups does sucrose contain?

Eight Signup and view all the answers

What reaction occurs between D-glucose and hydroxylamine (NH2OH)?

Formation of an oxime Signup and view all the answers

Which type of compounds cannot undergo hydrogen bonding with water?

Hydrocarbons Signup and view all the answers

What can be inferred about the relationship between the number of −OH groups and water solubility?

More −OH groups increase solubility Signup and view all the answers

What classification is given to monosaccharides that contain an aldehyde group?

Aldoses Signup and view all the answers

Which of the following types of sugars are considered reducing sugars?

All monosaccharides and disaccharides excluding sucrose Signup and view all the answers

What is the main use of cellulose in plants?

Building the cell wall Signup and view all the answers

When RNA is hydrolyzed, what does the lack of relationship among the quantities of different bases indicate?

RNA is single-stranded Signup and view all the answers

Which type of monosaccharide contains 3 carbon atoms and has a keto group?

Ketotriose Signup and view all the answers

What characteristic distinguishes polysaccharides from monosaccharides?

Polysaccharides consist of multiple sugar units Signup and view all the answers

Which of these is a function of starch in plants?

Energy storage Signup and view all the answers

How are monosaccharides classified?

By their functional group and carbon atom number Signup and view all the answers

Which of the following substances is a monosaccharide?

Fructose Signup and view all the answers

What type of linkage connects two monosaccharides?

Glycosidic linkage Signup and view all the answers

What are the products of hydrolysis for sucrose?

α-D glucose and β-D fructose Signup and view all the answers

Which component of starch has a linear structure?

Amylose Signup and view all the answers

How does glycogen differ from starch in terms of structure?

Glycogen is more branched than amylopectin Signup and view all the answers

What is produced from the hydrolysis of lactose?

β-D galactose and β-D glucose Signup and view all the answers

Which type of molecular bond is responsible for linking glucose units in amylose?

C1-C4 glycosidic linkage Signup and view all the answers

Which of the following is NOT a disaccharide?

Galactose Signup and view all the answers

What type of linkage connects the glucose units in amylopectin?

C1−C4 glycosidic linkage Signup and view all the answers

What compound is produced when D-glucose is treated with Br2 water?

D-gluconic acid Signup and view all the answers

Which of the following statements accurately describes essential amino acids?

They must be obtained through diet. Signup and view all the answers

What happens to D-glucose when treated with HNO3?

It is oxidized to saccharic acid. Signup and view all the answers

Which form of glucose crystallizes at a higher temperature?

Beta-form Signup and view all the answers

Which test does D-glucose NOT undergo due to the absence of a free -CHO group?

Tollens' test Signup and view all the answers

Which type of amino acids can be synthesized by the human body?

Non-essential amino acids Signup and view all the answers

What is a characteristic feature of cellulose compared to amylopectin?

Cellulose is composed of β-D-glucose, while amylopectin is composed of ∝-D-glucose. Signup and view all the answers

What type of sugar is found in DNA?

β-D-2 deoxyribose Signup and view all the answers

Which base pair combinations are found in the DNA structure?

Adenine-Thymine Signup and view all the answers

What is a key functional difference between DNA and RNA?

DNA is responsible for heredity, while RNA transfers coded messages. Signup and view all the answers

Which statement about the structural difference between DNA and RNA is accurate?

DNA has a double-helical structure; RNA is single-stranded. Signup and view all the answers

Which of the following is NOT a type of RNA found in the cell?

Microbial RNA (μ-RNA) Signup and view all the answers

Which statement best describes the role of messenger RNA?

It carries genetic information from DNA to ribosomes. Signup and view all the answers

Which of the following pairs of bases does match correctly in DNA?

Adenine - Thymine Signup and view all the answers

What is the function of transfer RNA in cells?

It transports amino acids to ribosomes during protein synthesis. Signup and view all the answers

Study Notes

Monosaccharides

Carbohydrates that can't be broken down further into simpler units
Classified based on the number of carbon atoms and the functional group present
Aldoses contain an aldehyde group
Ketoses contain a keto group
Further classified by the number of carbon atoms. For example:
Ketotriose: 3 carbon ketose
Aldotriose: 3 carbon aldose

### Reducing Sugars

Carbohydrates that reduce Fehling's solution and Tollen's reagent.
Include all monosaccharides and disaccharides except sucrose.

### Carbohydrate Function in Plants

Polysaccharides like starch serve as storage molecules
Cellulose, a polysaccharide, forms the cell wall.

### Hydrophilic Properties of Carbohydrates

Glucose and sucrose have multiple -OH groups, allowing for extensive hydrogen bonding with water, making them soluble
Cyclohexane and benzene lack -OH groups, preventing hydrogen bonding and making them insoluble in water.

### Hydrolysis of Lactose

Lactose is composed of β-D galactose and β-D glucose.
On hydrolysis, it yields these two monosaccharides.

### Glycosidic Linkage

The bond formed between two monosaccharide units by the loss of a water molecule.
For example, in a sucrose molecule, ∝-glucose and β-fructose are linked by a glycosidic linkage.

### Glycogen vs. Starch

Both are carbohydrates
Glycogen is stored in animals
Starch is composed of amylose (15-20%) and amylopectin (80-85%)
Glycogen is similar in structure to amylopectin, but highly branched

### Hydrolysis Products of Sucrose and Lactose

Sucrose hydrolysis yields one molecule of ∝-D glucose and one molecule of β-D fructose.
Lactose hydrolysis yields β-D-galactose and β-D-glucose.

### Starch and Cellulose: Structural Differences

Starch consists of:
Amylose: linear chain of ∝−D−(+)−glucose units linked by C1−C4 glycosidic linkage
Amylopectin: branched-chain polymer of ∝-D-glucose units linked by C1−C4 and C1−C6 glycosidic linkages
Cellulose: straight-chain polysaccharide of β-D-glucose units joined by C1−C4 glycosidic linkage.

### D-glucose Reactions

HI: Prolonged heating produces n-hexane
Bromine water: Produces D-gluconic acid
HNO3: Oxidizes D-glucose to saccharic acid

### D-glucose: Open Chain Structure

D-glucose does not show typical aldehyde reactions: 2, 4-DNP test, Schiff's test, or reaction with NaHSO4
Pentaacetate of glucose does not react with hydroxylamine, indicating an absence of a free -CHO group
Two crystalline forms of glucose ∝ and β, exist, not explainable with its open chain structure.

### Essential and Non-Essential Amino Acids

Essential: required by the body but cannot be synthesized (e.g., valine, leucine).
Non-Essential: Required by the body but can be synthesized (e.g., glycine, alanine).

### DNA Structure

Double-stranded helix
Each strand consists of a sugar-phosphate backbone, alternating between deoxyribose and phosphate groups.
Bases attached to the sugar molecules project inward
Bases on opposite strands pair through hydrogen bonding: adenine (A) with thymine (T), cytosine (C) with guanine (G)

### DNA vs. RNA Structure and Function

DNA*
Sugar: β-D-2'deoxyribose
Bases: adenine (A), guanine (G), cytosine (C), thymine (T)
Double-stranded helix
Functions:
- Chemical basis of heredity
- Carries genetic information
RNA*
Sugar: β-D-Ribose
Bases: adenine (A), guanine (G), cytosine (C), uracil (U)
Single-stranded
Functions:
- Protein synthesis
- Carries coded message for protein synthesis
- Transmits genetic information from DNA to ribosomes

### RNA Types

Messenger RNA (mRNA): carries genetic code from DNA to ribosomes for protein synthesis
Ribosomal RNA (rRNA): structural component of ribosomes, essential for protein synthesis
Transfer RNA (tRNA): carries amino acids to the ribosomes during protein synthesis

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Description

Explore the essential concepts of monosaccharides, including their classification and properties. This quiz encompasses the characteristics of reducing sugars, the function of carbohydrates in plants, and the solubility due to hydrophilic properties. Test your understanding of these fundamental carbohydrate topics.