Biology Chapter 5: Lipids and Carbohydrates
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Questions and Answers

What are the primary molecules that make up many lipids?

  • Fatty acids and cholesterol
  • Fatty acids and glycerol (correct)
  • Glycerol and carbohydrates
  • Glycerol and amino acids

    • Saturated fatty acids contain at least one double bond between carbon atoms.

    False

    What type of fatty acids have a kink in their hydrocarbon chain?

    Unsaturated fatty acids

    Triglycerides are formed when _____ hydroxyl groups of glycerol condense with fatty acids.

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

    What is an element?

    <p>A fundamental substance consisting of only one type of atom</p> Signup and view all the answers

    The atomic number of an atom is equal to the number of neutrons it contains.

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

    Match the type of fatty acid with its characteristics:

    <p>Saturated = No double bonds Monounsaturated = One double bond Polyunsaturated = Multiple double bonds Trans fats = Rare in nature</p> Signup and view all the answers

    Which of the following is a common hexose monosaccharide?

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

    What particles are found in the nucleus of an atom?

    <p>Protons and neutrons</p> Signup and view all the answers

    Pentoses contain 6 carbon atoms.

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

    What are triglycerides primarily used for in the body?

    <p>Energy storage</p> Signup and view all the answers

    What is the chemical formula for glucose?

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

    Isotopes are atoms of the same element that have the same number of protons but a different number of ______.

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

    Unsaturated fatty acids generally have higher melting temperatures than saturated fatty acids.

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

    What is the general formula for fatty acids?

    <p>R.COOH</p> Signup and view all the answers

    Ribose and deoxyribose are examples of ______.

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

    Which shell can hold the maximum number of electrons among the following?

    <p>Third shell</p> Signup and view all the answers

    Match the following atomic particles with their characteristics:

    <p>Protons = Positive charge, located in the nucleus Neutrons = No charge, located in the nucleus Electrons = Negative charge, orbiting around the nucleus</p> Signup and view all the answers

    Match the following monosaccharides with their characteristics:

    <p>Glucose = Most common monosaccharide in living organisms Fructose = Found in fruit Galactose = Part of lactose Ribose = Component of RNA</p> Signup and view all the answers

    An atom is considered neutral when the number of protons equals the number of ______.

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

    What type of linkage is found in disaccharides like maltose?

    <p>1,4 glycosidic linkage</p> Signup and view all the answers

    The first electron shell can hold a maximum of 8 electrons.

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

    All carbohydrates are either aldehydes or ketones.

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

    What structural form do sugars with 5 and 6 carbon atoms form in solution?

    <p>Ring structures</p> Signup and view all the answers

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

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

    α-glucose and β-glucose differ in the position of the —OH group on carbon 1.

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

    What are the two forms of glucose when it forms a ring structure?

    <p>α-glucose and β-glucose</p> Signup and view all the answers

    Lactose consists of glucose and __________.

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

    What is the glycosidic linkage in sucrose?

    <p>α1-2</p> Signup and view all the answers

    Match the following disaccharides with their components:

    <p>Maltose = Glucose + Glucose Lactose = Glucose + Galactose Sucrose = Glucose + Fructose</p> Signup and view all the answers

    Polysaccharides are formed by two or more monosaccharides linked by glycosidic bonds.

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

    Which oligosaccharides are essential for human ABO blood type specificity?

    <p>Oligosaccharides chains</p> Signup and view all the answers

    What is the role of allosteric enzymes in metabolic pathways?

    <p>They regulate metabolic pathways through negative feedback inhibition.</p> Signup and view all the answers

    Citrate enhances the activity of phosphofructokinase (PFK).

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

    What is the term used to describe the binding site on an allosteric enzyme that is different from the active site?

    <p>allosteric regulatory site</p> Signup and view all the answers

    When the end-product of a metabolic pathway accumulates, it may act as an allosteric __________ on the enzyme controlling the first step of the pathway.

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

    Match the following molecules with their roles in glycolysis:

    <p>ATP = Negative inhibitor of phosphofructokinase Citrate = Inhibitor indicating sufficient products for Kreb's cycle Phosphofructokinase (PFK) = Controls the third step of glycolysis ADP = Indicates a need for more ATP production</p> Signup and view all the answers

    Which of the following statements about allosteric enzymes is true?

    <p>They can be inhibited or enhanced by molecules binding to sites other than the active site.</p> Signup and view all the answers

    The accumulation of ATP signals the need for glycolysis to continue.

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

    What is the most important regulatory enzyme in glycolysis?

    <p>phosphofructokinase (PFK)</p> Signup and view all the answers

    What shape does a water molecule generally take due to the distribution of its charge?

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

    Water cannot dissolve ionic compounds because it is a polar molecule.

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

    What is the angle between the hydrogen-oxygen-hydrogen bonds in a water molecule?

    <p>104.5 degrees</p> Signup and view all the answers

    Water is known as a __________ solvent due to its ability to dissolve many substances.

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

    Match the following terms with their descriptions:

    <p>Hydrophilic = Substances that do not dissolve in water Hydrophobic = Substances that attract and dissolve in water Covalent bond = Type of bond formed between oxygen and hydrogen in water Hydration shell = Layer of water molecules surrounding a dissolved ion or molecule</p> Signup and view all the answers

    Which property of water is primarily responsible for its ability to form hydrogen bonds?

    <p>It is a polar molecule.</p> Signup and view all the answers

    Life on Earth could exist without water as it does not play a crucial role in biological systems.

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

    Charged and polar molecules that are attracted to water are termed __________.

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

    Study Notes

    Biochemistry (Basic Molecules and Enzymes)

    • Syllabus Section 2: Covers biomolecules like carbohydrates, lipids, proteins, and nucleic acids.

    The Biomolecules of Life

    • Carbohydrates: Basic chemical formula is Cx(H₂O)y. Examples include pentoses (e.g., ribose, deoxyribose) and hexoses (e.g., glucose, fructose, galactose).

    • Lipids: Includes triglycerides, phospholipids, and steroids. Lipids are hydrophobic (insoluble in water). Triglycerides are formed from glycerol and fatty acids. Phospholipids have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails. Steroids have a complex ring structure.

    • Proteins: Made up of amino acids linked by peptide bonds. Structure is crucial for function. Proteins have primary, secondary, tertiary, and quaternary structures. Examples include collagen and enzymes.

    • Nucleic Acids: DNA and RNA are polymers of nucleotides, which consist of a sugar, a nitrogenous base, and a phosphate group. DNA is double-stranded, while RNA is single-stranded.

    Basic Chemistry

    • Matter: Anything that takes up space and has mass. Composed of elements.

    • Elements: Substances that cannot be broken down into simpler substances. The most common in living organisms are carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

    • Atoms: The smallest unit of an element. Composed of a nucleus with protons and neutrons, with electrons orbiting the nucleus. Atoms have equal numbers of protons and electrons, making them electrically neutral.

    • Isotopes: Atoms of the same element, with varying numbers of neutrons.

    • Electron Shells: Electrons orbit the nucleus in specific energy levels called shells. Electrons fill the lowest energy levels first. Each shell has a maximum capacity for electrons.

    • Atomic Number: The number of protons in an atom's nucleus (symbol Z). Equal to the number of electrons in a neutral atom.

    • Mass Number: The total number of protons and neutrons in an atom's nucleus (symbol A).

    Chemical Bonds

    • Ionic Bonds: Formed from the transfer of electrons between a metal and a non-metal atom. Forms ions, which are attracted to one another.

    • Covalent Bonds: Formed when atoms share one or more pairs of electrons. Strong bonds, important for molecular structure.

    • Polar Covalent Bonds: Unequal sharing of electrons in a covalent bond, leading to partial charges on atoms (polarity).

    • Hydrogen Bonds: Attractive forces between a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) and another electronegative atom. Important in water and biological molecules.

    • Van der Waals Forces: Weak attractions between molecules due to temporary fluctuations in electron distribution.

    Water

    • Properties: High polarity, high heat capacity, high heat of vaporisation, high cohesion, and less dense as a solid. These contribute to life on Earth.

    Carbohydrates

    • Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose).
    • Disaccharides: Formed by combining two monosaccharides (e.g., maltose, sucrose, lactose).
    • Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose). Starch and glycogen are storage forms of glucose in plants and animals, respectively. Cellulose is a structural component of plant cell walls.

    Lipids

    • Fatty Acids: Long hydrocarbon chains with a carboxyl group (-COOH). Saturated fatty acids have no double bonds; unsaturated fatty acids have one or more double bonds. Oils and fats are made up of these molecules in different ratios and bonds.
    • Triglycerides: Esters of glycerol and three fatty acids. Major energy storage molecules in organisms.
    • Phospholipids: Lipids containing a phosphate group. Form the major component of cell membranes due to their amphipathic nature.
    • Steroids: Have a complex ring structure. Include cholesterol, vitamin D, and steroid hormones.
    • Important Roles: Energy storage, insulation, structural components.

    Proteins

    • Amino Acids: Monomers of proteins.
    • Peptide Bonds: Covalent bonds linking amino acids to form polypeptides.
    • Primary Structure: The linear sequence of amino acids in a polypeptide chain.
    • Secondary Structure: Local folding patterns in the polypeptide chain (alpha-helix and beta-sheet).
    • Tertiary Structure: The three-dimensional shape of a protein, stabilized by various interactions between amino acid side chains (R groups).
    • Quaternary Structure: The arrangement of multiple polypeptide chains in a protein.
    • Globular Proteins: Compact and folded, often enzymes and hormones.
    • Fibrous Proteins: Extended, often structural proteins (e.g., collagen).

    Enzymes

    • Catalysts: Organic proteins that speed up biochemical reactions.
    • Active Site: Region of the enzyme where the substrate binds.
    • Substrate: The molecule(s) acted upon by the enzyme.
    • Enzyme-Substrate Complex: The temporary complex formed when an enzyme binds to its substrate.
    • Products: The molecules formed after the reaction.
    • Lock-and-Key Model: The enzyme's active site precisely fits the substrate.
    • Induced Fit Model: The active site changes shape slightly to accommodate the substrate.
    • Factors Affecting Enzyme Activity: Temperature, pH, substrate concentration, and enzyme concentration.

    Vitamins and Coenzymes

    • Coenzymes: Non-protein organic molecules that assist enzymes in their function.
    • Vitamins: Essential organic compounds that are precursors of coenzymes.

    Nucleic Acids

    • Nucleotides: Monomers of nucleic acids (DNA and RNA).
    • Components: Sugar, nitrogenous base, and phosphate group.
    • DNA: Deoxyribonucleic acid. Double-stranded helix.
    • RNA: Ribonucleic acid. Single-stranded.

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    Test your knowledge on the essential concepts of lipids and carbohydrates. This quiz covers topics such as fatty acids, triglycerides, and the characteristics of sugars. Get ready to dive into the molecular structures that play vital roles in biological systems!

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