Biomolecules and Carbohydrates
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Biomolecules and Carbohydrates

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What is the primary function of carbohydrates in cell walls and exoskeletons?

  • Structural component (correct)
  • Energy source and energy storage
  • Cell signaling
  • Informational molecules

    • What is the chemical formula of carbohydrates?

  • CH4O
  • (CH2O)n (correct)
  • C5H10O5
  • C6H12O6

    • What is the molecular weight range of carbohydrates?

  • 1000-100,000 Da
  • 10-100 Da
  • 90-200,000,000 Da (correct)
  • 100-1000 Da

    • What is the name of the process by which plants produce carbohydrates?

    <p>Photosynthesis</p> Signup and view all the answers

    What is the term for a group of atoms within a molecule with distinctive chemical properties?

    <p>Functional group</p> Signup and view all the answers

    What is the term for the process of covalently linking carbohydrates with proteins?

    <p>Glycosylation</p> Signup and view all the answers

    What is the term for the role of carbohydrates in cell-cell signaling?

    <p>Informational molecules</p> Signup and view all the answers

    What is the name of the carbohydrate molecule with a molecular weight of 90 Da?

    <p>Glyceraldehyde</p> Signup and view all the answers

    What is the simplest carbohydrate that exists in two isomeric forms that are mirror images of each other?

    <p>Glyceraldehyde</p> Signup and view all the answers

    What is the term for a compound that contains an asymmetric center and thus can occur in two non-superposable mirror-image forms?

    <p>Chiral compound</p> Signup and view all the answers

    What is the purpose of a polarising filter in the context of optically active compounds?

    <p>To pass only waves with vibration aligned in the same direction</p> Signup and view all the answers

    In a Fischer projection formula, where is the carbonyl group situated?

    <p>At the top</p> Signup and view all the answers

    What is the term for a carbon atom that has four different substituents attached?

    <p>Chiral atom</p> Signup and view all the answers

    What is the term for a molecule that can be superimposed on its mirror image?

    <p>Achiral molecule</p> Signup and view all the answers

    What is the term for the rotation of the plane of vibration of light caused by a chiral compound?

    <p>Optical activity</p> Signup and view all the answers

    In a sugar molecule, which carbon atom is designated as D or L?

    <p>The carbon atom farthest from the carbonyl carbon</p> Signup and view all the answers

    What is the primary characteristic that distinguishes aldoses from ketoses?

    <p>The presence of an aldehyde group or a ketone group</p> Signup and view all the answers

    What is the term for a simple sugar that consists of a single sugar unit?

    <p>Monosaccharide</p> Signup and view all the answers

    How are the carbon atoms in a monosaccharide numbered?

    <p>Based on the location of the carbonyl carbon atom</p> Signup and view all the answers

    What is the general formula for a hexose sugar?

    <p>C6H12O6</p> Signup and view all the answers

    What is the suffix of glucose and fructose?

    <p>-ose</p> Signup and view all the answers

    Why do carbohydrates have many isomers?

    <p>Because of the arrangement of the -OH groups in their structures</p> Signup and view all the answers

    What is the characteristic of an aldose sugar?

    <p>The carbonyl carbon atom is at the end of the carbon chain</p> Signup and view all the answers

    What is the primary reason why obtaining enantiomerically pure compounds is important in medicine?

    <p>To reduce toxicity and improve selectivity</p> Signup and view all the answers

    Which of the following sugars is a ketose?

    <p>Fructose</p> Signup and view all the answers

    What is the main difference between enantiomers and epimers?

    <p>Enantiomers are non-superposable mirror images, while epimers differ in configuration at one asymmetric center</p> Signup and view all the answers

    What is the characteristic that distinguishes L and D enantiomers of a chiral molecule?

    <p>Different directions of rotation of plane-polarized light</p> Signup and view all the answers

    What is the term for a sugar molecule that contains an aldehyde or ketone group and two or more hydroxyl groups?

    <p>Saccharide</p> Signup and view all the answers

    Why do some simple sugars occur in the L-form?

    <p>Because they have different biological properties</p> Signup and view all the answers

    What is the term for a chiral center in a molecule?

    <p>Asymmetric center</p> Signup and view all the answers

    What is the primary role of chirality in biology?

    <p>To influence the biological properties of molecules</p> Signup and view all the answers

    What is an example of a pair of epimers?

    <p>D-glucose and 2-deoxy-D-glucose</p> Signup and view all the answers

    What determines the classification of monosaccharides?

    <p>The number of carbon atoms and the functional 'carbonyl' group</p> Signup and view all the answers

    What is a characteristic of sugars that differ in configuration at only one carbon atom?

    <p>They are epimers</p> Signup and view all the answers

    What type of representation is used to show the configuration of groups around chiral centers?

    <p>Fischer projection formulas</p> Signup and view all the answers

    What is the term for a simple sugar in which the carbonyl carbon atom is a ketone?

    <p>Ketose</p> Signup and view all the answers

    What is the bond between a sugar and another molecule through an intervening oxygen?

    <p>Glycosidic bond</p> Signup and view all the answers

    What is the term for a carbohydrate consisting of several monosaccharide groups joined by glycosidic bonds?

    <p>Oligosaccharide</p> Signup and view all the answers

    What is the term for a carbohydrate consisting of a single sugar unit?

    <p>Monosaccharide</p> Signup and view all the answers

    What is the term for a linear or branched polymer of monosaccharide units linked by glycosidic bonds?

    <p>Polysaccharide</p> Signup and view all the answers

    What type of stereoisomers are glucose, galactose, and fructose?

    <p>Isomers</p> Signup and view all the answers

    What is the term for the carbon atom in a sugar molecule that has four different substituents attached?

    <p>Chiral center</p> Signup and view all the answers

    What type of bond is formed when an aldehyde is attacked by an alcohol?

    <p>Hemiacetal</p> Signup and view all the answers

    What is the term for a sugar molecule with a carbonyl group that is a ketone?

    <p>Ketose</p> Signup and view all the answers

    Why do some simple sugars occur in the L-form?

    <p>Because they are the mirror image of the D-form</p> Signup and view all the answers

    What is the term for the process of a sugar molecule forming a ring structure?

    <p>Cyclisation</p> Signup and view all the answers

    What is the characteristic that distinguishes aldoses from ketoses?

    <p>The presence of an aldehyde or ketone group</p> Signup and view all the answers

    What is the term for a carbon atom with four different substituents attached?

    <p>Chiral center</p> Signup and view all the answers

    What is the result of the condensation reaction between two monosaccharides?

    <p>Formation of a glycosidic bond</p> Signup and view all the answers

    What is the role of the anomeric carbon in glycosidic bond formation?

    <p>It participates in the condensation reaction</p> Signup and view all the answers

    What is the difference between a hemiacetal and an acetal?

    <p>A hemiacetal is formed from a monosaccharide, while an acetal is formed from two monosaccharides</p> Signup and view all the answers

    What is the term for a disaccharide with no reducing ends?

    <p>Nonreducing disaccharide</p> Signup and view all the answers

    What is the purpose of the Haworth perspective formula?

    <p>To represent the chemical structure of a monosaccharide</p> Signup and view all the answers

    What is the term for the process by which a hydroxyl group from one monosaccharide adds to the anomeric carbon of another monosaccharide?

    <p>Condensation</p> Signup and view all the answers

    What is the characteristic of a nonreducing disaccharide?

    <p>It has no reducing ends</p> Signup and view all the answers

    What is the term for a molecule formed by the condensation of two alcohol molecules with an aldehyde molecule?

    <p>Acetal</p> Signup and view all the answers

    What type of bond is formed between two monosaccharide units in a disaccharide?

    <p>Glycosidic bond</p> Signup and view all the answers

    What is the term for a sugar that cannot donate electrons to other molecules and therefore cannot act as a reducing agent or be oxidized in aqueous solution?

    <p>Non-reducing sugar</p> Signup and view all the answers

    What is the term for the carbon atom in a sugar at the new stereocenter formed when a sugar cyclizes to form a hemiacetal?

    <p>Anomeric carbon</p> Signup and view all the answers

    What type of reaction is involved in the formation of a hemiacetal?

    <p>Nucleophilic addition</p> Signup and view all the answers

    What is the term for a method for representing cyclic chemical structures so as to define the configuration of each substituent group?

    <p>Haworth perspective formulas</p> Signup and view all the answers

    What type of reaction is involved in the condensation of two monosaccharides to form a disaccharide?

    <p>Condensation reaction</p> Signup and view all the answers

    What is the term for two stereoisomers of a given sugar that differ only in the configuration about the carbonyl (anomeric) carbon atom?

    <p>Anomers</p> Signup and view all the answers

    What is the term for a carbohydrate consisting of two covalently joined monosaccharide units?

    <p>Disaccharide</p> Signup and view all the answers

    What is the difference between α-Glucose and β-Glucose?

    <p>The placement of the hydroxyl group on Carbon 1</p> Signup and view all the answers

    What is the result of nucleophilic attack on the anomeric carbon in aldopyranose?

    <p>The formation of a hemiacetal linkage</p> Signup and view all the answers

    What is the term for the carbon atom that becomes a new chiral center during cyclisation of monosaccharides?

    <p>Anomeric carbon</p> Signup and view all the answers

    What is the type of ring formed when the hydroxyl group at C-5 (or C-6) reacts with the keto group at C-2?

    <p>Furanose</p> Signup and view all the answers

    What is the most common anomer of D-Fructose?

    <p>β-D-Fructofuranose</p> Signup and view all the answers

    What is the term for the process of intramolecular cyclisation of monosaccharides?

    <p>Cyclisation</p> Signup and view all the answers

    What is the effect of mutarotation on the anomeric carbon?

    <p>It changes the configuration of the hydroxyl group</p> Signup and view all the answers

    What is the difference between aldofuranose and aldopyranose?

    <p>The stability of the ring</p> Signup and view all the answers

    What is the configuration of the hydroxyl group if it is on the opposite side of the ring as the CH2OH moiety?

    <p>b</p> Signup and view all the answers

    What type of reaction is a dehydration reaction?

    <p>Condensation</p> Signup and view all the answers

    What is the bond between two monosaccharides called?

    <p>Glycosidic bond</p> Signup and view all the answers

    What is the term for a monosaccharide that has a free hemiacetal?

    <p>Reducing sugar</p> Signup and view all the answers

    What is the glycosidic bond between monomers?

    <p>An acetal</p> Signup and view all the answers

    What is the term for the carbon atom involved in the glycosidic linkage?

    <p>Anomeric carbon</p> Signup and view all the answers

    What is the disaccharide formed by the condensation of two glucose molecules via a carbon 1-4 bond?

    <p>Maltose</p> Signup and view all the answers

    What is the significance of the hemiacetal at the second monomer?

    <p>It makes the sugar reducing</p> Signup and view all the answers

    Agarose is a component of which substance commonly used in laboratories?

    <p>Agar</p> Signup and view all the answers

    What is the primary function of the extracellular matrix (ECM)?

    <p>To provide structural support to cells</p> Signup and view all the answers

    What type of polymers are glycosaminoglycans?

    <p>Linear heteropolysaccharides</p> Signup and view all the answers

    What is the characteristic that distinguishes polysaccharides from other carbohydrates?

    <p>They serve as stored fuel and structural components</p> Signup and view all the answers

    What is the primary function of peptidoglycan in bacterial cell walls?

    <p>To provide structural support</p> Signup and view all the answers

    What is the role of hyaluronan in the extracellular matrix (ECM)?

    <p>To aid diffusion and provide support</p> Signup and view all the answers

    What is the characteristic of agarose and agar solutions?

    <p>They form gels at low temperatures</p> Signup and view all the answers

    What is the primary function of cellulose in plant cell walls?

    <p>To provide structural support</p> Signup and view all the answers

    What is the role of glycosaminoglycans in the extracellular matrix (ECM)?

    <p>To support and aid diffusion</p> Signup and view all the answers

    What is the characteristic of glycans?

    <p>They serve as stored fuel and structural components</p> Signup and view all the answers

    Study Notes

    Carbohydrates

    • Carbohydrates are the most abundant biomolecule on Earth, with approximately 100 billion metric tons produced annually through photosynthesis.
    • They are a vital dietary staple in many parts of the world, and their functions include energy source, energy storage, structural component, and informational molecules.
    • Carbohydrates can be covalently linked with proteins to form glycoproteins, glycolipids, and proteoglycans.

    Classification of Carbohydrates

    • Carbohydrates are classified based on the number of carbon atoms they have, with the formula (CH2O)n, where 'n' is the number of carbon atoms ≥ 3.
    • They can range in size from small (e.g., glyceraldehyde, Mw = 90 Da) to huge (e.g., amylopectin, Mw = 200,000,000 Da).

    Functional Groups of Biomolecules

    • A functional group is a group of atoms within a molecule with distinctive chemical properties.
    • When two or more substituents are shown in a molecule, they are designated as R1, R2, and so forth.

    Monosaccharides

    • Monosaccharides are classified into two classes: aldoses and ketoses, based on the type of carbonyl group they possess.
    • Aldoses have an aldehyde group, while ketoses have a ketone group.
    • Monosaccharides can also be classified based on the number of carbon atoms they have, such as trioses, tetroses, pentoses, and hexoses.

    Fischer Projection Formulas

    • Fischer projection formulas are a 2D method for representing 3D molecules to show the configuration of groups around chiral centers.
    • The carbonyl group is situated at the top, and the last achiral CH2OH is at the bottom.

    Chiral Centers and Enantiomers

    • Chiral centers are atoms with substituents arranged so that the molecule is non-superposable on its mirror image.
    • Enantiomers are stereoisomers that are non-superposable mirror images of each other.
    • Chiral compounds can interact with polarized light, causing the plane of vibration to rotate.

    Importance of Enantiomers

    • Obtaining enantiomerically pure compounds is crucial in medicine, as the two enantiomers of a chiral molecule can have very different biological properties.
    • Enantiomers can differ in bioavailability, rate of metabolism, metabolites, excretion, potency, selectivity, and toxicity.

    Epimers

    • Epimers are two sugars that differ only in the configuration around one carbon atom.
    • D-glucose and D-mannose are examples of epimers.

    Definitions

    • Aldose: A simple sugar in which the carbonyl carbon atom is an aldehyde.
    • Carbohydrate: A sugar (monosaccharide) or one of its dimers (disaccharide) or polymers (polysaccharide).
    • Chiral center: An atom with substituents arranged so that the molecule is non-superposable on its mirror image.
    • Chiral compound: A compound that contains an asymmetric center (chiral atom or chiral center) and thus can occur in two non-superposable mirror-image forms.
    • Disaccharide: A carbohydrate consisting of two covalently joined monosaccharide units.
    • Enantiomers: Stereoisomers that are non-superposable mirror images of each other (L - laevorotatory and D - dextrorotatory).
    • Fischer projection formulas: A 2D method for representing 3D molecules to show the configuration of groups around chiral centers.
    • Glycosidic bond: Bonds between a sugar and another molecule (typically an alcohol, purine, pyrimidine, or sugar) through an intervening oxygen.
    • Isomers: Any two molecules with the same molecular formula but a different arrangement of molecular groups.
    • Ketose: A simple monosaccharide in which the carbonyl group is a ketone.
    • Monosaccharide: A carbohydrate consisting of a single sugar unit.
    • Oligosaccharide: Several monosaccharide groups joined by glycosidic bonds.
    • Polysaccharide: A linear or branched polymer of monosaccharide units linked by glycosidic bonds.

    Monosaccharides

    • Monosaccharides can exist in a straight or cyclic structure.
    • In aqueous solutions, aldotetroses and monosaccharides with 5 or more carbon atoms occur predominantly as cyclic structures.
    • Glucose, Galactose, and Fructose are all isomers of one another (same chemical formula, different structural formula).

    Cyclic Structure: Hemiacetals and Hemiketals

    • Aldehyde and ketone carbons are electrophilic, while alcohol oxygen atoms are nucleophilic.
    • When aldehydes are attacked by alcohols, hemiacetals form, and when ketones are attacked by alcohols, hemiketals form.
    • Formation of an additional asymmetric carbon atom (anomeric carbon) can exist in two stereoisomeric forms.

    Cyclisation of Monosaccharides

    • There can be multiple configurations of a ring structure.
    • Two possible ring structures for Glucose exist: α-Glucose and β-Glucose.
    • The difference between α-Glucose and β-Glucose is the placement of the hydroxyl group on Carbon 1.
    • Aldopyranose is more stable than aldo furanose.
    • Mutarotation occurs when the anomeric carbon is attacked by a nucleophile.

    Anomers

    • Anomers are two stereoisomers of a given sugar that differ only in the configuration about the carbonyl (anomeric) carbon atom.
    • The anomeric carbon is the carbon atom in a sugar at the new stereocenter formed when a sugar cyclizes to form a hemiacetal.

    Disaccharides

    • Two monosaccharides bond together (dehydration reaction) to form a carbohydrate called a disaccharide.
    • A dehydration reaction is a condensation reaction, where two molecules combine to form one single molecule, losing a small molecule in the process.
    • The bond between two monosaccharides is known as a glycosidic bond.

    The Glycosidic Bond

    • Two sugar molecules can be joined via a glycosidic bond between an anomeric carbon and a hydroxyl carbon.
    • The glycosidic bond (an acetal) between monomers is less reactive than the hemiacetal at the second monomer.
    • A second monomer with a hemiacetal is reducing, while the anomeric carbon involved in the glycosidic linkage is non-reducing.

    Non-Reducing Disaccharides

    • Two sugar molecules can also be joined via a glycosidic bond between two anomeric carbons.
    • No remaining hemiacetals are present, and the product has two acetal groups and no hemiacetals.
    • There are no reducing ends, and this is a non-reducing sugar.

    Key Concepts

    • Haworth perspective formulas are a method for representing cyclic chemical structures to define the configuration of each substituent group.
    • Hemiacetal/Hemiketal is formed when an alcohol oxygen atom adds to the carbonyl carbon of an aldehyde or a ketone following nucleophilic attack.
    • Nucleophilic addition is the initial attack of a nucleophile (hydroxyl group) on the slightly positive carbon center of the carbonyl group.
    • Reducing sugar is a sugar in which the carbonyl (anomeric) carbon is not involved in a glycosidic bond and can therefore undergo oxidation.
    • Non-reducing sugar is a carbohydrate that cannot donate electrons to other molecules and therefore cannot act as a reducing agent or be oxidized in aqueous solution.

    Polysaccharide Structure

    • Polysaccharides can be composed of 1, 2, or several different monosaccharides in straight or branched chains of varying length.

    Homopolysaccharides

    • A homopolysaccharide is a polysaccharide made up of one type of monosaccharide unit.
    • Examples: starch, glycogen, chitin, cellulose.

    Heteropolysaccharides

    • A heteropolysaccharide is a polysaccharide containing more than one type of sugar.
    • Examples: agarose, peptidoglycans, glycosaminoglycans.

    Starch

    • Starch is a mixture of two homopolysaccharides of D-glucose: amylose and amylopectin.
    • Amylose is an unbranched polymer of (α1 → 4) linked residues with a molecular weight that varies from a few thousand to over 1 million.
    • Amylopectin is branched like glycogen, but the branch-points with (α1 → 6) linkers occur every 24–30 residues, with a molecular weight of up to 200 million.
    • Starch is the main storage polysaccharide in plants and is heavily hydrated due to the number of exposed -OH groups.

    Glycogen

    • Glycogen is a branched homopolysaccharide of glucose.
    • Glucose monomers form (α1 → 4) linked chains.
    • Branch-points with (α1 → 6) linkers occur every 8–12 residues, making it more compact than starch.
    • Molecular weight reaches several millions, and it functions as the main storage polysaccharide in animals, abundant in the liver and skeletal muscle.

    Other Polysaccharides

    • Dextrans: bacterial and yeast polysaccharides, with poly-D-glucose forming (α1 → 6) linked chains.
    • Cellulose: an unbranched homopolysaccharide of glucose, with D-glucose monomers forming (β1 → 4) linked chains.
    • Chitin: a linear homopolysaccharide of N-acetylglucosamine (NAG), found in cell walls of mushrooms and exoskeletons of insects, spiders, and other arthropods.
    • Agar and Agarose: complex mixtures of heteropolysaccharides containing modified galactose units, used in laboratory settings.
    • Glycosaminoglycans: linear polymers with repeating disaccharide units, found in animals and bacteria, containing sulfate groups.

    Polysaccharide Functions

    • Serve as stored fuel and structural components of cell walls and extracellular matrix.
    • Some homopolysaccharides fold in 3D, forming helical structures with interchain hydrogen bonding.
    • Heteropolysaccharides, such as peptidoglycan and agar, strengthen bacterial and algal cell walls.
    • Glycosaminoglycans provide support and aid diffusion in the extracellular matrix.

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    Description

    This quiz covers the importance of carbohydrates, types of biomolecules, and their functions in cells and organisms. It also touches on their role in cell recognition and adhesion.

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