NUCLEIC ACID PRACTICE SHEET KEY

  1. What are nucleic acids? Why are they important?

    Nucleic acids contain our genetic material. They contain the information necessary for cellular growth and reproduction. Our ability to function as living organisms is possible because of the many proteins that carry out biological processes. The information needed to synthesize these proteins comes from nucleic acids.

  2. What are the two types of nucleic acids, and what are their main differences?

    Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) are two types of nucleic acids. Deoxyribonucleic acids are composed of a ribose sugar that has a H instead of a hydroxyl group at the 2’ position. RNA contains the base uracil instead of thymine. DNA remains in the nucleus, whereas RNA moves to the cytoplasm of a cell to carry out translation (protein synthesis).

     

  3. DNA and RNA occur as polymers. What is their monomer called? What are the three components of this monomer and draw the general structure.

    The monomeric units are called nucleotides. The three components are: base, sugar, phosphate group.

     

  4. Why do think nucleotides are also sometimes referred to as "bases" or "nucleotide bases"?

    The bases contain nitrogen, which are basic since their lone pair can accept a H+

    What is the difference between a nucleotide and a nucleoside? Explain by giving an example, using structures.

    A nucleoside is composed of a base attached to a sugar. Once the nucleoside is phosphorylated

    (on the sugar) a nucleotide is obtained.

     

  5. Draw the nucleotides, deoxyguanosine triphosphate (dGTP) and thymidine monophosphate (TMP).

                     

     

     

  6. What kind of bond links a base to a sugar? Is the sugar an alpha or beta anomer? In what position(s) of the sugar does this occur? In what position(s) of the base does this occur?

    A glycosidic bond links the base to a sugar. The oxygen on carbon 1 is replaced by N (in the base). The ribose or deoxyribose sugar is in the beta position.

     

  7. The bond that links a base to a sugar is a glycosidic bond. What is the name of the kind ofbond that links a sugar to a phosphate group?

    Phosphodiester bond.

     

  8. In proteins, a peptide read from the N terminal to the C terminal. Is there a kind of direction in DNA/RNA as well? Briefly explain.

    Yes, there is a 5’à 3’ direction of DNA. The 5’ phosphate group is free. Additional nucleotides are attached by their phosphate groups to the 3’ hydroxyl group of the previous nucleotide. When there are no more nucleotides to be added, the 3’ hydroxyl is free.

     

  9. What kinds of forces hold the double strands of a DNA double helix together? Do the two strands go in the same direction or in opposite directions?

    Hydrogen bonding between base pairs hold the two DNA strands together. A strand in the 5’ to

    3’ direction is paired with a strand going in the 3’ to 5’ direction.

     

  10. Three types of RNA involved in comprising the structural and functional core for protein synthesis, serving as a template for translation, and transporting amino acid, Define each type

  1. Define codon.

    A codon is a three-letter code for an amino acid.

     

  2. Shown below is the sequence of bases in a portion of a DNA molecule that codes for a protein. Use this information, along with the simplified version of the genetic code at the bottom of the page, to answer the following questions: