Nucleic acids + ATP

• Name the type of bond between complementary base pairs

  Hydrogen bonds
• Name the type of bond between adjacent nucleotides in a DNA strand

  Phosphodiester bonds
• Describe the structure of DNA.

  1. Polymer of nucleotides;

  2. Each nucleotide formed from deoxyribose, a phosphate group and an nitrogenous base;

  3. Phosphodiester bonds between nucleotides;

  4. Double helix held by hydrogen bonds;

  5. Hydrogen bonds between adenine, thymine and cytosine, guanine;

  6. Hydrogen bonds between complementary base pairs
• Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule.

  1. Condensation reaction resulting in loss of water;

  2. Between phosphate and deoxyribose;

  3. Catalysed by DNA polymerase;
• Name the protein associated with DNA in a chromosome

  histone
• In the process of semi-conservative DNA replication, the two strands within a DNA molecule are separated. Each then acts as a template for the formation of a new complementary strand.

  Describe how the separation of strands occurs.

  1. DNA helicase;

  2. Breaks hydrogen bonds between complementary bases
• Describe the role of DNA polymerase in the semi-conservative replication of DNA.

  1. Joins adjacent DNA nucleotides;

  2. Catalyses condensation reactions;

  3. Catalyses formation of phosphodiester bonds between adjacent nucleotides;
• Name the two scientists who proposed models of the chemical structure of DNA and of DNA replication.

  Watson and Crick
• A scientist replicated DNA in a test tube. To do this, he mixed an enzyme with identical single-stranded DNA fragments and a solution containing DNA nucleotides.

  Name the enzyme used in this DNA replication.

  DNA polymerase;
• Use your knowledge of semi-conservative replication of DNA to suggest:

  1. the role of the single-stranded DNA fragments

  1. Template;

  2. Determines order of nucleotides/bases;
• Use your knowledge of semi-conservative replication of DNA to suggest:

  2. the role of the DNA nucleotides.

  Forms complementary DNA strand;
• Give features of DNA and explain how each one is important in the semi-conservative replication of DNA.

  1. Weak hydrogen bonds between bases allow two strands to unzip;

  2. Two strands, so both can act as templates;

  3. Complementary base pairing allows accurate replication;
• Describe the role of two named enzymes in the process of semiconservative replication of DNA.

  1. DNA helicase causes breaking of hydrogen bonds between DNA strands;

  2. DNA polymerase joins the DNA nucleotides;

  3. Forming phosphodiester bonds;
• The enzymes DNA helicase and DNA polymerase are involved in DNA replication. Describe the function of each of these enzymes.

  1. DNA helicase - unwinding DNA and breaking hydrogen bonds between bases

  2. DNA polymerase - joins adjacent nucleotides and forms phosphodiester bond
• Adenosine triphosphate (ATP) is a nucleotide derivative.

  Contrast the structures of ATP and a nucleotide found in DNA to give differences.

  1. ATP has ribose and DNA nucleotide has deoxyribose;

  2. ATP has 3 phosphate groups and DNA nucleotide has 1 phosphate group;

  3. ATP – base always adenine and in DNA nucleotide base can be varies;
• Describe how an ATP molecule is formed from its component molecules

  1. Adenine, ribose/pentose, three phosphates;

  2. Condensation reaction

  3. Catalysed by ATP synthase
• Water is used to hydrolyse ATP.

  Name the two products of ATP hydrolysis.

  Adenosine diphosphate and inorganic phosphate;
• Scientists investigated treatment of a human bladder infection caused by a species of bacterium. This species of bacterium is often resistant to the antibiotics currently used for treatment. They investigated the use of a new antibiotic to treat the bladder infection. The new antibiotic inhibits the bacterial ATP synthase enzyme.

  The new antibiotic is safe to use in humans because it does not inhibit the ATP synthase found in human cells.

  Suggest why human ATP synthase is not inhibited and bacterial synthase is inhibited.

  Human ATP synthase has a differenttertiarystructure to bacterial ATP synthase
• ATP is an energy source used in many cell processes.

  Give ways in which ATP is a suitable energy source for cells to use.

  1. Releases relatively small amount of energy so little energy lost as heat;

  2. Releases energy instantaneously;

  3. Phosphorylates other compounds, making them more reactive;

  4. Can be rapidly re-synthesised;

  5. Does not leave cells.
• Cells constantly hydrolyse ATP to provide energy.

  Describe how ATP is resynthesised in cells.

  1. From ADP and phosphate;

  2. By ATP synthase;

  3. During respiration/photosynthesis;
• Give two ways in which the hydrolysis of ATP is used in cells.

  1. To provide energy for other reactions

  2. To add phosphate to other substances and make them more reactive or change their shape;