Exercises

Part I

  1. A nucleotide of DNA may contain ________.

    1. ribose, uracil, and a phosphate group
    2. deoxyribose, uracil, and a phosphate group
    3. deoxyribose, thymine, and a phosphate group
    4. ribose, thymine, and a phosphate group

    2. The building blocks of nucleic acids are ________.

    1. sugars
    2. nitrogenous bases
    3. peptides
    4. nucleotides

    3. What are the structural differences between RNA and DNA?

    4. What are the four types of RNA and how do they function?

Part II

  1. Which of the following is not true about enzymes:

    1. They increase ∆G of reactions
    2. They are usually made of amino acids
    3. They lower the activation energy of chemical reactions
    4. Each one is specific to the particular substrate(s) to which it binds

    2. An allosteric inhibitor does which of the following?

    1. Binds to an enzyme away from the active site and changes the conformation of the active site, increasing its affinity for substrate binding
    2. Binds to the active site and blocks it from binding substrate
    3. Binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate
    4. Binds directly to the active site and mimics the substrate

    3. Which of the following analogies best describe the induced-fit model of enzyme-substrate binding?

    1. A hug between two people
    2. A key fitting into a lock
    3. A square peg fitting through the square hole and a round peg fitting through the round hole of a children’s toy
    4. The fitting together of two jigsaw puzzle pieces.

    4. With regard to enzymes, why are vitamins necessary for good health? Give examples.

    5. Explain in your own words how enzyme feedback inhibition benefits a cell.

Part II

  1. The monomers that make up proteins are called ________.

    1. nucleotides
    2. disaccharides
    3. amino acids
    4. chaperones

    2. The α helix and the β-pleated sheet are part of which protein structure?

    1. primary
    2. secondary
    3. tertiary
    4. quaternary

    3. Explain what happens if even one amino acid is substituted for another in a polypeptide chain. Provide a specific example.

    4. Describe the differences in the four protein structures.

Part IV

  1. Saturated fats have all of the following characteristics except:

    1. they are solid at room temperature
    2. they have single bonds within the carbon chain
    3. they are usually obtained from animal sources
    4. they tend to dissolve in water easily

    2. Phospholipids are important components of ________.

    1. the plasma membrane of animal cells
    2. the ring structure of steroids
    3. the waxy covering on leaves
    4. the double bond in hydrocarbon chains

    3. Explain at least three functions that lipids serve in plants and/or animals.

    4. Why have trans fats been banned from some restaurants? How are they created?

Part V

  1. An example of a monosaccharide is ________.
  1. fructose
  2. glucose
  3. galactose
  4. all of the above

2. Cellulose and starch are examples of:

  1. monosaccharides
  2. disaccharides
  3. lipids
  4. polysaccharides

3.  Plant cell walls contain which of the following in abundance?

  1. starch
  2. cellulose
  3. glycogen
  4. lactose

4.  Lactose is a disaccharide formed by the formation of a ________ bond between glucose and ________.

  1. glycosidic; lactose
  2. glycosidic; galactose
  3. hydrogen; sucrose
  4. hydrogen; fructose

5. Describe the similarities and differences between glycogen and starch.

6. Why is it impossible for humans to digest food that contains cellulose?