Biochemistry: Proteins and Carbohydrates
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Questions and Answers

What is a key characteristic of enzymes?

  • They are made of lipids.
  • They can speed up reactions without being consumed. (correct)
  • They have a fixed shape throughout their function.
  • They change the properties of the substrates.

    • All enzymes are non-proteins.

    False

    Name one example of a contractile protein.

    myocin or actin

    The primary structure of proteins is determined by the sequence of __________.

    <p>amino acids</p> Signup and view all the answers

    Match the types of proteins with their examples:

    <p>Structural proteins = collagen Transport proteins = haemoglobin Enzymes = amylase Protective proteins = antibodies</p> Signup and view all the answers

    Which type of bond is NOT present in globular proteins?

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

    Enzymes can catalyze only one type of reaction.

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

    What structural component often binds multiple globular molecules in quaternary protein structure?

    <p>hydrogen bonds</p> Signup and view all the answers

    Which of the following are considered classes of biomolecules?

    <p>All of the above</p> Signup and view all the answers

    Carbohydrates are only composed of monosaccharides.

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

    What is the primary sugar found in fruits?

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

    The two main processes regarding biomolecules are _____ and catabolism.

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

    Match the following terms to their definitions:

    <p>Monosaccharides = Simple sugars that cannot be hydrolyzed Polysaccharides = Macromolecules formed by the linkage of multiple sugars Glycogen = A storage form of glucose in animals Cellulose = A structural component in plant cell walls</p> Signup and view all the answers

    What type of carbohydrate is sucrose classified as?

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

    Structural changes in carbohydrates can affect their functional properties.

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

    Name one macromolecular carbohydrate.

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

    What type of sugars are predominantly found in humans?

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

    All monosaccharides exist in both pyranose and furanose forms in solution.

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

    What is the general formula for a disaccharide?

    <p>CnH2nOn-1</p> Signup and view all the answers

    Maltose is produced during the hydrolysis of _____ by α-amylase.

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

    Match the following types of sugars to their descriptions:

    <p>D-sugars = Predominant type of sugars in humans L-fucose = An example of an L-form sugar Pyranose = Six-membered ring structure Furanose = Five-membered ring structure</p> Signup and view all the answers

    What linkage is found in maltose?

    <p>α(1 → 4) linkage</p> Signup and view all the answers

    α-anomers have the hydroxyl group on the right side of the anomeric carbon.

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

    What type of carbon is formed during the cyclization of aldose and ketose sugars?

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

    What type of glycosidic linkage is present in lactose?

    <p>β(1 → 4)</p> Signup and view all the answers

    Sucrose is a reducing sugar due to the presence of a free aldehyde group.

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

    What are the two monosaccharides that compose sucrose?

    <p>glucose and fructose</p> Signup and view all the answers

    The molecular formula for polysaccharides is (C6H10O5)_____

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

    Match the following carbohydrates with their classifications:

    <p>Starch = Homopolysaccharide Glycogen = Homopolysaccharide Mucopolysaccharides = Heteropolysaccharide Lactose = Disaccharide</p> Signup and view all the answers

    Which of the following is true about maltose?

    <p>It has a free hydroxyl group on C-1 of the second sugar.</p> Signup and view all the answers

    Oligosaccharides consist of more than ten monosaccharide units.

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

    Where is starch most commonly found in nature?

    <p>In cereals, grains, potatoes, carrots, millets, and legumes</p> Signup and view all the answers

    What is the term for the enzyme-cofactor complex?

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

    Competitive inhibitors can be reversed by increasing the concentration of substrate.

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

    Name two types of reversible inhibitors.

    <p>Competitive and non-competitive</p> Signup and view all the answers

    The optimum temperature for enzyme activity is usually below _____ degrees Celsius.

    <p>60</p> Signup and view all the answers

    Match the following types of inhibitors with their characteristics:

    <p>Competitive = Binds to active site, can be outcompeted by substrate Non-competitive = Binds to a different site and alters enzyme structure Reversible = Can be removed or overcome Non-reversible = Irreversibly binds and inactivates enzyme</p> Signup and view all the answers

    Which of the following substances is NOT considered a non-reversible inhibitor?

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

    Apoenzyme is the enzyme component that has its cofactor attached.

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

    What is the effect of pH on enzyme activity?

    <p>Alters enzyme shape and reduces activity.</p> Signup and view all the answers

    What happens to the rate of reaction when substrate concentration is increased beyond a certain point?

    <p>It remains constant.</p> Signup and view all the answers

    Increasing enzyme concentration will always lead to a constant rate of reaction in living systems.

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

    What are the three factors that are kept constant in the reaction medium when examining substrate and enzyme concentrations?

    <p>Temperature, pH value, and enzyme (or substrate) concentration.</p> Signup and view all the answers

    When the substrate concentration is too high, all active sites of enzyme molecules are __________.

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

    Match the following effects with the appropriate concentration changes:

    <p>Increasing substrate concentration = Rate of reaction increases until saturation Increasing enzyme concentration = Rate of reaction continuously increases High enzyme concentration = Does not stabilize due to high substrate concentration Low substrate concentration = Rate of reaction is limited</p> Signup and view all the answers

    What happens to the rate of reaction when the substrate concentration is increased gradually up to a certain point?

    <p>The rate of reaction increases.</p> Signup and view all the answers

    What occurs when the substrate concentration is high enough that all active sites of enzyme molecules are saturated?

    <p>Further increases in substrate concentration have no significant effect.</p> Signup and view all the answers

    When the concentration of the enzyme is increased while keeping the substrate concentration constant, what is the expected effect on the reaction rate?

    <p>The reaction rate eventually stabilizes at a constant level.</p> Signup and view all the answers

    In living systems, why is the concentration of substrate compared to enzyme concentration considered to be very high?

    <p>Substrates are consumed faster than they are produced.</p> Signup and view all the answers

    Which statement accurately describes the behavior of enzymes as the concentration of the enzyme increases?

    <p>The rate of reaction will always reach a plateau.</p> Signup and view all the answers

    What type of sugar forms the backbone of most sugars in humans?

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

    Which describes the formation of a hemiacetal?

    <p>Aldehyde reacting with one hydroxyl group</p> Signup and view all the answers

    Which structure has six carbon members and one oxygen?

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

    Which carbon becomes the anomeric carbon in aldose sugars?

    <p>C-1</p> Signup and view all the answers

    What type of linkage connects the two glucose molecules in maltose?

    <p>α(1 → 4)</p> Signup and view all the answers

    Which of the following substances undergoes hydrolysis to yield two moles of monosaccharides?

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

    In which form do most monosaccharides exist in solution?

    <p>Cyclic form only</p> Signup and view all the answers

    What is the general molecular formula for disaccharides?

    <p>CnH2nOn-1</p> Signup and view all the answers

    What term is used to describe the enzyme portion without its cofactor?

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

    What are the two main processes involved in the metabolism of biomolecules?

    <p>Anabolism and catabolism</p> Signup and view all the answers

    Which class of biomolecules includes starch and glycogen?

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

    What is a characteristic of non-competitive inhibitors?

    <p>They do not compete with the substrate for binding.</p> Signup and view all the answers

    Which of the following substances is classified as a non-reversible inhibitor?

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

    Which of the following is NOT a classification of carbohydrates?

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

    What happens to enzyme activity when the pH value deviates from the optimum range?

    <p>Enzyme activity diminishes.</p> Signup and view all the answers

    What is the primary function of nucleic acids?

    <p>Storing genetic information</p> Signup and view all the answers

    At approximately what temperature does enzyme denaturation typically begin to occur?

    <p>60°C</p> Signup and view all the answers

    Which type of carbohydrate is primarily found in fruits?

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

    What defines the optimum pH for an enzyme's activity?

    <p>The pH at which the maximum rate of reaction occurs.</p> Signup and view all the answers

    What term describes the small molecules that make up carbohydrates?

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

    Which regulatory mechanism is involved in the metabolism of biomolecules?

    <p>Feedback inhibition</p> Signup and view all the answers

    What are cofactors primarily responsible for?

    <p>Facilitating chemical reactions by altering enzyme shape.</p> Signup and view all the answers

    Which statement accurately describes lactose?

    <p>Lactose contains a free anomeric carbon.</p> Signup and view all the answers

    What is the effect of competitive inhibitors on enzymatic reactions?

    <p>They can be overcome with an increased substrate concentration.</p> Signup and view all the answers

    What type of bond links the monosaccharides in sucrose?

    <p>α, β(1 → 2) glycosidic linkage</p> Signup and view all the answers

    Which characterizes the change in functional properties of carbohydrates?

    <p>Structural configuration</p> Signup and view all the answers

    Which of the following best describes the structure of starch?

    <p>Starch has a helical structure due to amylose.</p> Signup and view all the answers

    What is the characteristic of sucrose that differentiates it from maltose?

    <p>It is a non-reducing sugar.</p> Signup and view all the answers

    Which of the following correctly defines oligosaccharides?

    <p>Carbohydrates that yield two to ten monosaccharides.</p> Signup and view all the answers

    What distinguishes homopolysaccharides from heteropolysaccharides?

    <p>Heteropolysaccharides have different monosaccharide units.</p> Signup and view all the answers

    Which of the following best describes the composition of maltotriose?

    <p>It consists of three glucose units.</p> Signup and view all the answers

    In which type of plant sources is sucrose predominantly found?

    <p>Sugarcane and sugar beet</p> Signup and view all the answers

    What role do enzymes play in metabolic reactions?

    <p>They catalyse reactions</p> Signup and view all the answers

    Which of the following is a characteristic of enzymes?

    <p>They have a specific 3D shape</p> Signup and view all the answers

    Which bonds primarily hold the globular proteins in a quaternary structure together?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What is true about the enzyme activity with respect to substrate concentration?

    <p>It increases until a saturation point is reached</p> Signup and view all the answers

    Which type of protein is collagen classified as?

    <p>Structural protein</p> Signup and view all the answers

    How many globular molecules can typically combine to form a quaternary protein structure?

    <p>2-4 globular molecules</p> Signup and view all the answers

    Which of the following factors does NOT affect enzyme activity?

    <p>Concentration of caffeine</p> Signup and view all the answers

    What is the role of genes concerning enzymes?

    <p>They provide information to synthesize proteins</p> Signup and view all the answers

    Proteins are made up of amino acids.

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

    Study Notes

    Biomedical Science Course - Biochemistry Module

    • The course is offered by LSBU (London South Bank University), established in 1892.
    • The Biochemistry module is taught by Dr. Mohammed Mansour.
    • The lecturer has a PhD in Cancer Biology from Nagoya University's Graduate School of Medicine (2012-2015).
    • Postdoctoral experience includes research at the CRUK Beatson Institute in Glasgow (2017-2019), a Newton international fellowship and the University of Southampton (2019-2020).
    • The lecturer is also a Lecturer in Biomedical Science at LSBU since 2020.

    Module Aims

    • Provide a broad understanding of the structure, types, and functions of the four main classes of biomolecules.
    • Identify key metabolic pathways and specific regulatory mechanisms involving biomolecules.
    • Introduce the principles of basic techniques and assays used to detect biomolecules in a laboratory setting.

    Lectures Contents

    • Carbohydrates and protein structure
    • Lipids and nucleic acids structure
    • Carbohydrates metabolism
    • Protein metabolism
    • Lipids metabolism
    • Nucleic acids metabolism

    Carbohydrates

    • Carbohydrates are polyhydroxy aldehydes or ketones that store energy and are membrane components.
    • Classified into Monosaccharides, Disaccharides, Oligosaccharides, and Polysaccharides.
    • Monosaccharides: Simple sugars (e.g., glucose, fructose), cannot be hydrolysed further. Subdivided based on carbon atoms (trioses, tetroses, pentoses, hexoses, heptoses) and aldehyde/ketone groups (aldose/ketose).
    • Stereoisomers: Compounds with the same formula but different spatial configurations. Monosaccharides contain asymmetric carbons, leading to isomers (enantiomers and epimers). Glucose has 16 isomers.
    • Epimers: Stereoisomers differing in the configuration of a single asymmetric carbon (e.g., mannose and glucose).
    • Enantiomers: Mirror images of each other (e.g., D-fructose and L-fructose). Most sugars in humans are D-sugars.
    • HEMIACETAL FORMATION: In acidic conditions, aldehydes combine with one or two hydroxyl groups of an alcohol, forming a hemiacetal or acetal.
    • PYRANOSE AND FURANOSE RINGS: Haworth proposed cyclic ring structures (pyranose and furanose) for sugars. Most monosaccharides exist in ring forms in solution.
    • ANOMERS: Asymmetric carbons created during cyclisation are anomeric; ring structure formed between carbonyl and alcohol group.
    • α- and β- anomers: Configurations of the anomeric carbon (α if H is on the right, β if OH is on the right). Enzymes are specific to different configurations (e.g. amylase can only catalyze α-1,4 linkages).
    • Disaccharides: Two monosaccharides linked by a glycosidic linkage (e.g., Maltose, Lactose, Sucrose).
    • Maltose: Two glucose molecules linked by α(1→4) linkage. A reducing sugar.
    • Lactose: Galactose and glucose linked by β(1→4) linkage. A reducing sugar.
    • Sucrose: Glucose and fructose linked by α, β (1→2) linkage. A non-reducing sugar.
    • Oligosaccharides: Yield 2-10 monosaccharides upon hydrolysis.
    • Polysaccharides: Composed of more than twelve monosaccharides upon hydrolysis.
      • Homopolysaccharides: Similar monosaccharide units (e.g., starch, glycogen, cellulose, inulin, agar, dextrans, chitin).
      • Heteropolysaccharides: Different monosaccharide units (e.g., mucopolysaccharides).
      • Starch: Made up of amylose and amylopectin; amylose is a helical unbranched chain, amylopectin has branching.
      • Glycogen: Storage form of glucose in animals (branched).

    Proteins

    • Proteins are macromolecules constructed from amino acid residues.
    • Amino acids have an amino group (NH2) and a carboxyl group (COOH) attached to the same alpha carbon (α-amino acids).
    • Amino acids:
      • Essential: Cannot be synthesized by the body (10 essential amino acids).
      • Non-essential: Can be synthesized by the body.
      • 20 common amino acids used in protein synthesis.
    • Amino acids:
      • L amino acids participate in protein synthesis.
      • Amino acids are colourless and crystallise.
      • Amino acids undergo condensation reactions to form polypeptide chains.
    • Protein structure: Primary, Secondary, Tertiary, and Quaternary levels.
    • Primary Structure: Sequence of amino acids in the polypeptide chain; held together by peptide bonds.
    • Secondary Structure: Hydrogen bonds give rise to α-helices or β-pleated sheets in chains.
    • Tertiary Structure: Overall 3D arrangement of the polypeptide chain; held by various interactions (hydrogen bonds, disulphide bonds, ionic bonds).
    • Quaternary Structure: Multiple polypeptide chains assemble into a functional protein; held by hydrogen bonds.
    • Major Functions of Proteins: Structural proteins, Enzymes, Transport proteins, Protective proteins, Contractile proteins, Storage proteins, Toxins. (Examples given for each).
    • Enzymes: Globular proteins, catalyze metabolic reactions, increase reaction rate by lowering activation energy.

    Enzyme Activity

    • Enzymes are specific.
    • Enzymes have active sites that complement the shape of substrates, therefore there is the lock and key model and induced fit model.
    • Factors that affect enzyme activity: Cofactors, Inhibitors, pH value, Temperature, Substrate concentration and Enzyme concentration.
    • Cofactors: Non-protein helpers; inorganic ions, prosthetic groups, coenzymes.
    • Inhibitors: Reversible/irreversible, competitive/non-competitive.
    • pH Value & Temperature: Enzymes function best at optimum values.
    • Substrate Concentration: Enzyme activity increases with increasing substrate concentration until saturation.
    • Enzyme Concentration: Enzyme activity increases with increasing enzyme concentration.

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    Description

    Test your knowledge on the key characteristics of proteins and carbohydrates in this biochemistry quiz. Explore different types of proteins, their structures, and the classification of carbohydrates. Perfect for students studying biochemistry or related fields.

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