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General Biology: Biological Molecules and Their Functions

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Termini in questo insieme (29)

  • Why is carbon central to the chemistry of life?
    Carbon has 4 electrons in its valence shell, allowing it to form 4 covalent bonds with other atoms, enabling the formation of large, complex, and diverse organic molecules.
  • What are isomers?
    Compounds with the same molecular formula but different structural arrangements, resulting in different shapes and properties.
  • What are hydrocarbons and their biological significance?
    Molecules consisting only of carbon and hydrogen; they are major components of petroleum and provide energy, and hydrocarbon chains are found in fats as energy sources.
  • List four ways carbon skeletons can vary.
    Length, branching, presence and location of double bonds, and ring formation.
  • What are functional groups and why are they important?
    Specific groups of atoms attached to carbon skeletons that affect a molecule's function by participating in chemical reactions and influencing polarity and solubility.
  • Name six important chemical groups in biological molecules.
    Hydroxyl (-OH), Carbonyl (C=O), Carboxyl (-COOH), Amino (-NH2), Phosphate (PO4), and Methyl (-CH3).
  • What is a dehydration reaction?
    A chemical reaction that links monomers by removing a water molecule, forming a covalent bond.
  • What is hydrolysis?
    A reaction that breaks polymers into monomers by adding a water molecule, reversing dehydration.
  • What are the four main classes of biological macromolecules?
    Carbohydrates, lipids, proteins, and nucleic acids.
  • What are monosaccharides?
    Simple sugars that serve as monomers for carbohydrates, typically with molecular formulas that are multiples of CH2O.
  • How do glucose and fructose differ despite having the same formula?
    They are isomers differing in the arrangement of atoms, especially the position of the carbonyl group.
  • What is a disaccharide and how is it formed?
    A sugar composed of two monosaccharides linked by a dehydration reaction.
  • Compare starch and cellulose.
    Both are glucose polymers; starch is helical and used for energy storage in plants, while cellulose has a different linkage forming straight fibers for structural support.
  • Why are lipids hydrophobic?
    Because they contain mostly nonpolar hydrocarbon chains that do not interact well with water.
  • What distinguishes saturated from unsaturated fatty acids?
    Saturated fatty acids have no double bonds and are solid at room temperature; unsaturated fatty acids have one or more double bonds causing kinks and are liquid at room temperature.
  • What are trans fats and why are they harmful?
    Trans fats are unsaturated fats that have been hydrogenated to be more solid; they increase the risk of heart disease more than saturated fats.
  • What is the structure and function of phospholipids?
    Phospholipids have two fatty acids and a phosphate group attached to glycerol; they form the bilayer of cell membranes with hydrophilic heads and hydrophobic tails.
  • What are steroids and their biological role?
    Lipids with a carbon skeleton of four fused rings; cholesterol is a steroid important in cell membranes and as a precursor to sex hormones.
  • What are proteins and their primary function?
    Polymers of amino acids that perform diverse functions including catalysis (enzymes), transport, defense, signaling, movement, and structural support.
  • What determines a protein's function?
    Its unique three-dimensional shape, which depends on the amino acid sequence and folding.
  • What is denaturation?
    The process where a protein unravels and loses its shape and function due to factors like heat or pH changes.
  • What are amino acids composed of?
    A central carbon bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R group.
  • How are amino acids linked to form proteins?
    By peptide bonds formed through dehydration reactions between the carboxyl group of one amino acid and the amino group of another.
  • What are the four levels of protein structure?
    Primary (amino acid sequence), secondary (alpha helices and beta sheets), tertiary (3D folding), and quaternary (assembly of multiple polypeptides).
  • What are nucleotides?
    Monomers of nucleic acids composed of a five-carbon sugar, a phosphate group, and a nitrogenous base.
  • What bases are found in DNA and RNA?
    DNA has adenine (A), thymine (T), cytosine (C), guanine (G); RNA has A, uracil (U), C, and G.
  • How do DNA strands pair in the double helix?
    A pairs with T, and C pairs with G via hydrogen bonds, making the strands complementary.
  • What is the central dogma of molecular biology?
    DNA is transcribed into RNA, which is then translated into proteins.
  • What is lactose tolerance and its evolutionary significance?
    The ability to digest lactose into adulthood due to a recent genetic mutation, providing a survival advantage in populations with dairy farming.