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General Biology: The Molecules of Cells

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Termini in questo insieme (22)

  • Why is lactose intolerance considered normal in adult humans?
    Most adults lack the enzyme lactase, which is needed to digest lactose, making lactose intolerance the normal condition.
  • Why is carbon unparalleled in forming large, diverse molecules?
    Carbon can form four covalent bonds, allowing it to build large, complex, and diverse organic molecules.
  • Define organic compounds, hydrocarbons, carbon skeleton, and isomer.
    • Organic compounds: molecules with carbon atoms.
    • Hydrocarbons: compounds of only carbon and hydrogen.
    • Carbon skeleton: chain of carbon atoms forming the molecule's backbone.
    • Isomers: molecules with the same formula but different structures.
  • What role do chemical groups play in biological molecules?
    Chemical groups attached to carbon skeletons determine the molecule's properties and reactivity, influencing biological function.
  • What are the four main classes of macromolecules important to life?
    Carbohydrates, lipids, proteins, and nucleic acids.
  • How are monomers and polymers related?
    Monomers are small building blocks that join via dehydration synthesis to form polymers, which are large molecules.
  • What is dehydration synthesis and hydrolysis?
    • Dehydration synthesis: joining monomers by removing water.
    • Hydrolysis: breaking polymers into monomers by adding water.
  • What are monosaccharides and their general formula?
    Monosaccharides are simple sugar monomers with a formula generally a multiple of CH\(2\)O, containing hydroxyl and carbonyl groups.
  • How are disaccharides formed?
    Two monosaccharides bond via dehydration synthesis to form a disaccharide.
  • What are polysaccharides and examples of their functions?
    Long chains of sugar units; starch and glycogen store energy, cellulose provides structural support in plants, and chitin supports insect exoskeletons.
  • What distinguishes saturated, unsaturated, and trans fats?
    • Saturated fats: no double bonds, max hydrogens, found in animal fats.
    • Unsaturated fats: one or more double bonds, found in plant oils.
    • Trans fats: unsaturated fats hydrogenated to be saturated, linked to health risks.
  • Why are trans fats considered more harmful than saturated fats?
    Scientific studies show trans fats increase health risks more than saturated fats, based on controlled feeding trials and observational studies.
  • What unique structural property makes phospholipids essential for cell membranes?
    Phospholipids have hydrophilic heads and hydrophobic tails, forming bilayers that create cell membranes.
  • What are anabolic steroids and their health risks?
    Synthetic variants of testosterone abused by some athletes, causing serious health consequences.
  • List some functions of proteins in the body.
    Proteins function as enzymes, transporters, antibodies, hormones, receptors, contractile elements, structural components, and storage molecules.
  • What are the components of an amino acid?
    An amino group, a carboxyl group, a hydrogen atom, and an R group attached to a central carbon.
  • How are amino acids linked to form proteins?
    Amino acids join by dehydration synthesis forming peptide bonds between the carboxyl group of one and the amino group of another.
  • What are the four levels of protein structure?
    1. Primary: amino acid sequence.
    2. Secondary: local folding stabilized by hydrogen bonds.
    3. Tertiary: overall 3D shape from R group interactions.
    4. Quaternary: multiple polypeptide chains combined.
  • What causes protein denaturation and its effect?
    Denaturation unravels a protein's shape, causing loss of function, often due to heat, pH changes, or chemicals.
  • What are nucleotides composed of?
    A sugar, a phosphate group, and a nitrogenous base.
  • How do DNA and RNA differ structurally and functionally?
    DNA is a double helix storing genetic information; RNA is single-stranded and helps in protein synthesis.
  • What is the evolutionary significance of lactose tolerance?
    Mutations in some human groups keep the lactase gene active into adulthood, allowing digestion of lactose, an adaptation linked to dairy farming.