Biomolecules and Carbohydrates

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Questions and Answers

What are the melting points of the a-form and b-form of glucose?

The melting point of the a-form of glucose is 419 K and that of the b-form is 423 K.

How is the a-form of glucose obtained?

The a-form of glucose is obtained by crystallisation from a concentrated solution at 303 K.

What is the significance of the anomeric carbon in glucose?

The anomeric carbon is the carbon at C1 which determines the configuration of the cyclic forms of glucose.

What type of structure does glucose form when it cyclizes?

Glucose forms a six-membered ring structure known as the pyranose structure. Signup and view all the answers

What is fructose, and how is it related to sucrose?

Fructose is a ketohexose obtained by the hydrolysis of the disaccharide sucrose. Signup and view all the answers

What is the molecular formula of fructose, and how does it compare to glucose?

The molecular formula of fructose is C6H12O6, the same as that of glucose. Signup and view all the answers

Why are glucose's cyclic forms in equilibrium with the open chain structure?

Glucose's cyclic forms are in equilibrium with the open chain structure due to the reversible nature of the cyclization process. Signup and view all the answers

Describe the stereochemical characterization of fructose.

Fructose belongs to the D-series and is a laevorotatory compound, denoted as D-(–)-fructose. Signup and view all the answers

Why are essential amino acids important to our diet?

Essential amino acids are crucial because they cannot be synthesized by the body and must therefore be obtained through diet. Signup and view all the answers

What occurs during the denaturation of proteins?

Denaturation of proteins occurs when their secondary or tertiary structures are disturbed, often due to changes in pH or temperature. Signup and view all the answers

How do enzymes function as biocatalysts?

Enzymes function as biocatalysts by speeding up biochemical reactions, being highly specific and selective in their action. Signup and view all the answers

What are the two main types of nucleic acids and a key structural difference between them?

The two main types of nucleic acids are DNA and RNA, with DNA being a double-stranded molecule and RNA being single-stranded. Signup and view all the answers

What are vitamins and why are they necessary?

Vitamins are accessory food factors needed in the diet and are essential for various physiological functions. Signup and view all the answers

What is glycogen and how does it differ from starch?

Glycogen is a polysaccharide that serves as energy storage in animals, while starch is used for energy storage in plants. Signup and view all the answers

Explain what a glycosidic linkage is.

A glycosidic linkage is a covalent bond that joins a carbohydrate (sugar) to another group, which can also be a carbohydrate. Signup and view all the answers

What roles do carbohydrates play in plants?

Carbohydrates in plants primarily provide energy and serve as structural components. Signup and view all the answers

What are the three types of RNA and their primary functions?

The three types of RNA are messenger RNA (m-RNA), which carries genetic information from DNA, ribosomal RNA (r-RNA), which is a component of ribosomes, and transfer RNA (t-RNA), which helps in translating the m-RNA into proteins. Signup and view all the answers

What unique characteristic does DNA fingerprinting hold compared to traditional fingerprints?

DNA fingerprinting is unique to each individual and remains unchanged throughout a person's life, while traditional fingerprints can be altered. Signup and view all the answers

What is a tripeptide, and how is it formed?

A tripeptide is a molecule formed by the combination of three amino acids linked by two peptide linkages. Signup and view all the answers

How are polypeptides differentiated from proteins in terms of amino acid residue count?

Polypeptides are generally defined as chains with more than ten amino acids, while proteins typically consist of polypeptides with over hundred amino acid residues. Signup and view all the answers

Who shared the Nobel Prize for Medicine and Physiology in 1968 and for what achievement?

Har Gobind Khorana, Marshall Nirenberg, and Robert Holley shared the Nobel Prize for cracking the genetic code. Signup and view all the answers

What role does DNA play in heredity?

DNA serves as the chemical basis of heredity and is responsible for maintaining the identity of different species over generations. Signup and view all the answers

Describe the structural difference between fibrous and globular proteins.

Fibrous proteins have parallel polypeptide chains held together by bonds, forming an insoluble fiber-like structure, while globular proteins have coiled chains forming spherical shapes and are usually soluble in water. Signup and view all the answers

What bonds contribute to the structure of fibrous proteins?

Fibrous proteins are primarily held together by hydrogen and disulfide bonds. Signup and view all the answers

In which contexts is DNA fingerprinting utilized?

DNA fingerprinting is used in forensic laboratories for criminal identification, to determine paternity, to identify deceased individuals, and to study racial groupings. Signup and view all the answers

What are the four levels of protein structure and their complexity?

The four levels of protein structure are primary, secondary, tertiary, and quaternary, with each level representing increased complexity. Signup and view all the answers

Describe the secondary structure of RNA.

The secondary structure of RNA involves single-stranded helices that can sometimes fold back on themselves. Signup and view all the answers

Provide examples of fibrous and globular proteins.

Examples of fibrous proteins include keratin and myosin, while insulin and albumins are examples of globular proteins. Signup and view all the answers

What is the significance of Har Gobind Khorana's work?

Har Gobind Khorana's work significantly advanced our understanding of nucleic acids and helped elucidate how genetic information is translated into proteins. Signup and view all the answers

How is DNA's uniqueness determined?

The uniqueness of DNA is determined by the specific sequence of bases in each individual's DNA. Signup and view all the answers

What is the significance of the primary structure of proteins?

The primary structure of a protein refers to its specific sequence of amino acids, which determines the protein's overall structure and function. Signup and view all the answers

What term is used for polypeptides containing fewer than ten amino acids?

Polypeptides containing fewer than ten amino acids are typically not specifically classified and may still be considered part of a protein. Signup and view all the answers

What distinguishes monosaccharides from oligosaccharides in carbohydrate classification?

Monosaccharides cannot be hydrolyzed into simpler units, while oligosaccharides yield 2 to 10 monosaccharide units upon hydrolysis. Signup and view all the answers

Name a common disaccharide and the monosaccharides it hydrolyzes into.

Sucrose is a common disaccharide that hydrolyzes into glucose and fructose. Signup and view all the answers

What are polysaccharides, and why are they referred to as non-sugars?

Polysaccharides are carbohydrates that yield many monosaccharide units on hydrolysis and are referred to as non-sugars because they are not sweet in taste. Signup and view all the answers

What functional groups do carbohydrates contain that justify their classification as polyhydroxy aldehydes or ketones?

Carbohydrates contain multiple hydroxyl (-OH) groups and either an aldehyde or a ketone group. Signup and view all the answers

Provide an example of a carbohydrate that is not a sugar and explain why.

Cellulose is an example of a carbohydrate that is not a sugar because it is a polysaccharide that does not taste sweet. Signup and view all the answers

What environmental factor can affect the classification of carbohydrates?

The classification of carbohydrates can be affected by their behavior on hydrolysis. Signup and view all the answers

How many known monosaccharides exist in nature, and can you name a few?

About 20 monosaccharides are known to exist in nature, including glucose, fructose, and ribose. Signup and view all the answers

What are the key characteristics of oligosaccharides compared to monosaccharides?

Oligosaccharides consist of 2 to 10 monosaccharide units and can be hydrolyzed into these units, unlike monosaccharides which are single units. Signup and view all the answers

What are the two functional groups present in amino acids?

The two functional groups present in amino acids are amino (-NH2) and carboxyl (-COOH) groups. Signup and view all the answers

How are amino acids classified based on the position of the amino group?

Amino acids are classified as alpha (α), beta (β), gamma (γ), delta (δ), etc., depending on the relative position of the amino group to the carboxyl group. Signup and view all the answers

What is the significance of glycine's name in relation to its properties?

Glycine is named after the Greek word 'glykos', meaning sweet, because it has a sweet taste. Signup and view all the answers

What does the 'R' represent in the amino acid structure?

In the amino acid structure, 'R' represents the side chain or variable group that distinguishes different amino acids. Signup and view all the answers

How are amino acids commonly represented in terms of symbols?

Amino acids are commonly represented by a three-letter symbol and sometimes a one-letter code. Signup and view all the answers

What structural feature differentiates valine from other amino acids?

Valine has a branched side chain, specifically represented as (H3C)2CH-. Signup and view all the answers

What amino acid is characterized by having a longer carbon chain with an amino group at one end?

Lysine is characterized by having a longer carbon chain with an amino group at one end, specifically H2N-(CH2)4-. Signup and view all the answers

What common feature do all alpha-amino acids share?

All alpha-amino acids share the feature of having the amino group attached to the carbon adjacent to the carboxyl group. Signup and view all the answers

Study Notes

Biomolecules

Biomolecules are the fundamental building blocks of living systems
Living systems are composed of non-living atoms and molecules
Biomolecules are complex molecules like carbohydrates, proteins, nucleic acids, lipids, etc.
These molecules interact and form the molecular logic of life processes
Carbohydrates, proteins, nucleic acids and vitamins are significant constituents of food.
Structures and functions of some of these biomolecules are discussed

Carbohydrates

Carbohydrates are primarily produced by plants.
Common examples include cane sugar, glucose and starch.
General formula is Cx(H2O)y; considered hydrates of carbon.
Example: Glucose (C6H12O6) fits the formula C6(H2O)6.
Not all compounds fitting the formula are carbohydrates (e.g., acetic acid).
Chemically, carbohydrates are polyhydroxy aldehydes or ketones or compounds producing these units on hydrolysis.
Some are sweet (sugars), others are not (e.g., starch, cellulose).

Classification of Carbohydrates

Monosaccharides: Cannot be hydrolyzed further into simpler units (e.g., glucose, fructose).
Oligosaccharides: Yield 2-10 monosaccharide units on hydrolysis (e.g., disaccharides, trisaccharides).
Polysaccharides: Yield many monosaccharide units on hydrolysis (e.g., starch, cellulose, glycogen).

Monosaccharides

Classified by the number of carbon atoms and the functional group (aldehyde or ketone).
Aldoses: Contain an aldehyde group (e.g., glucose).
Ketoses: Contain a ketone group (e.g., fructose).

Glucose

Glucose is an aldohexose, also known as dextrose.
Molecular formula is C6H12O6.
Glucose forms a six-membered ring structure in solution.
It exists in two cyclic forms (α and β).

Fructose

Fructose is a ketohexose.
Molecular formula C6H12O6.
Found in fruits, honey, and vegetables.
Also exists in cyclic forms (α and β).

Disaccharides

Formed by the combination of two monosaccharides through a glycosidic linkage.
Example: Sucrose (glucose + fructose).
Sucrose is a non-reducing sugar (reducing groups are involved in linkage).
Maltose (glucose + glucose) is a reducing sugar.
Lactose (glucose + galactose) is a reducing sugar.

Polysaccharides

Long chains of monosaccharides linked by glycosidic bonds.
Starch: Plants' storage polysaccharide, composed of amylose and amylopectin.
Cellulose: Plant structural polysaccharide, composed of β-D-glucose units.
Glycogen: Animal storage polysaccharide, similar to amylopectin.

Proteins

Proteins are the most abundant biomolecules in living systems.
Made up of amino acids linked by peptide bonds.
Classified as acidic, basic, or neutral depending on the balance of amino and carboxyl groups.

Amino Acids

Building blocks of proteins.
Contain an amino group (-NH2) and a carboxyl group (-COOH).
Different side chains (R groups) distinguish each amino acid.
Some amino acids are essential for humans (cannot be synthesized).

Structure of Proteins

Primary structure: Linear sequence of amino acids.
Secondary structure: Folding patterns (α-helix, β-sheet).
Tertiary structure: Overall 3D shape of the polypeptide chain.
Quaternary structure: Arrangement of multiple polypeptide chains in a protein complex.

Denaturation of Proteins

Loss of secondary, tertiary, and quaternary structures, often due to heat or pH changes.
Proteins lose their biological activity.

Enzymes

Biological catalysts that speed up chemical reactions.
Mostly globular proteins.
Active sites catalyze reactions.
Mechanism involves lowering activation energy.

Vitamins

Organic compounds essential for specific biological functions.
Classified into fat-soluble (A, D, E, K) and water-soluble (B complex, C).
Deficiencies lead to specific diseases.

Nucleic Acids

DNA and RNA.
Polymers of nucleotides.
DNA: Deoxyribonucleic acid, double-stranded helix structure.
RNA: Ribonucleic acid, single-stranded structure, various types (mRNA, tRNA, rRNA).
Nucleic acids carry genetic information.

Hormones

Chemical messengers produced by endocrine glands.
Transported through the bloodstream.
Several functions including regulating growth, metabolism, response to stress, and reproduction.
Steroids, polypeptides, or amino acid derivatives.

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Description

Explore the fascinating world of biomolecules that are essential for all living systems. This quiz will delve into the structures and functions of various biomolecules, focusing specifically on carbohydrates, their production, and chemical properties. Test your knowledge and understanding of these complex molecules that form the basis of life.