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Anatomy & Physiology: Nucleic Acids and Lipids

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Terms in this set (22)

  • What are nucleic acids and their primary function?

    Nucleic acids are large molecules like DNA and RNA that store and encode genetic information required to build proteins.

  • What are the monomers of nucleic acids?

    The monomers of nucleic acids are nucleotides, each consisting of a phosphate group, a pentose sugar, and a nitrogenous base.

  • Name the nitrogenous bases found in DNA and RNA.

    DNA has adenine (A), thymine (T), cytosine (C), and guanine (G). RNA has adenine (A), uracil (U) instead of thymine, cytosine (C), and guanine (G).

  • How are nucleotides linked together in nucleic acids?

    Nucleotides are linked by dehydration synthesis forming a sugar-phosphate backbone with nitrogenous bases sticking out.

  • Describe the structure of DNA.

    DNA is a double-stranded polymer with complementary base pairing: A pairs with T, and C pairs with G, held together by hydrogen bonds forming a double helix.

  • What is the role of RNA in the cell?

    RNA is a single-stranded polymer that carries genetic information from DNA to the cytoplasm and helps in protein synthesis (mRNA, tRNA, rRNA).

  • What is the difference between DNA replication and transcription?

    DNA replication copies DNA strands to make new DNA, while transcription copies DNA into RNA using RNA nucleotides (U replaces T).

  • What are the four major classes of organic molecules in cells?

    Carbohydrates, proteins, nucleic acids, and lipids.

  • What is a polymer and a monomer in biological molecules?

    A polymer is a large molecule made of repeating subunits called monomers, e.g., proteins are polymers of amino acid monomers.

  • What is dehydration synthesis?

    A chemical reaction that joins monomers by removing a water molecule to form a covalent bond.

  • What is hydrolysis?

    A reaction that breaks polymers into monomers by adding a water molecule.

  • Why are hydrocarbons hydrophobic?

    Because carbon and hydrogen share electrons equally, forming nonpolar covalent bonds, hydrocarbons do not interact with water and are hydrophobic.

  • Are lipids polymers? Explain.

    Lipids are not polymers; they are mostly carbon and hydrogen linked by nonpolar bonds and are hydrophobic molecules.

  • What are the three main groups of lipids discussed?

    Fats (triglycerides), phospholipids, and steroids.

  • What is the structure of a triglyceride (fat)?

    A triglyceride consists of three fatty acids attached to one glycerol molecule.

  • What is the difference between saturated and unsaturated fatty acids?

    Saturated fatty acids have no double bonds and are straight, allowing tight packing; unsaturated fatty acids have one or more double bonds causing bends and looser packing.

  • How does saturation affect the physical state of fats at room temperature?

    Saturated fats are usually solid at room temperature; unsaturated fats are usually liquid due to bent fatty acid chains.

  • What is the structure and function of phospholipids?

    Phospholipids have two fatty acid tails (hydrophobic) and a phosphate head (hydrophilic), making them amphipathic and essential for forming cell membranes.

  • What does amphipathic mean?

    A molecule with both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

  • What is the characteristic structure of steroids?

    Steroids have a structure of four fused carbon rings and are derived from cholesterol.

  • Name some steroid hormones derived from cholesterol.

    Testosterone, estradiol (a form of estrogen), and cortisol are steroid hormones derived from cholesterol.

  • Why does fat store more energy than glycogen by weight?

    Fat stores about twice as much energy per kilogram as glycogen, so storing energy as glycogen requires more mass.