DNA & Nucleic Acids

• State two types of nucleic acids:

  • DNA
  • RNA
• DNA stands for deoxyribonucleic acid
• RNA stands for ribonucleic acid
• The monomer for DNA and RNA is nucleotide
• A nucleotide consist of:

  • phosphate group
  • pentose sugar
  • nitrogenous organic base
• State the three types of RNA:

  • mRNA
  • tRNA
  • rRNA
• What is mRNA?

  messenger ribonucleic acid

  = carries the complementary DNA code out of the nucleus to the ribosomes for protein synthesis
• What is tRNA?

  transfer ribonucleic acid

  = brings a specific amino acid from the cytoplasm to the ribosome for protein synthesis
• What is rRNA?

  ribosomal ribonucleic acid

  = a component of ribosomes which bind to the mRNA in the cytoplasm
• Nitrogenous organic bases are arranged in sequences of amino acids containing genetic codes in a protein molecule
• The single polynucleotide chain in RNA is held together by phosphodiester bonds between nucleotides.
• The two polynucleotide strands in DNA are antiparallel because they run in opposite directions
• Name the base pairs in DNA:

  • Adenine and Thymine
  • Guanine and Cytosine
• Name the base pairs in RNA:

  • Adenine and Uracil
  • Guanine and Cytosine
• Base pairing holds the two DNA polynucleotides together by hydrogen bonding
• Name the backbone of DNA:

  • Deoxyribose sugars
  • Phosphate groups
• DNA is made up of two polynucleotide strands that form a double helix
• In semi-conservative DNA replication, the new DNA is made up of one parent (original) polynucleotide strand and a new complementary polynucleotide strand
• DNA helicase breaks the hydrogen bonds between the two polynucleotide strands, the DNA helix unwinds and the two strands separate.
• In DNA replication, free nucleotides align to form hydrogen bonds with their complementary bases
• DNA polymerase forms phosphodiester bonds between adjacent nucleotides.
• Name the components of ATP:

  • Adenine
  • Ribose
  • Three phosphate groups
• The equation for the hydrolysis of ATP:

  ATP + H2O → ADP + Pi (+ energy)
• Are phosphate molecules organic or inorganic?

  Inorganic
• Phosphorylation:

  The inorganic phosphate released in ATP hydrolysis can be used to phosphorylate other compounds.

  This makes the compounds more reactive.
• Energy is released in ATP hydrolysis because one of the phosphate bonds breaks
• The hydrolysis of ATP can be coupled to other reactions within cells that need energy.

  E.g The transmembrane sodium-potassium pump :

  • Energy is released from the hydrolysis of ATP
  • It pushes sodium ions out of the cell and potassium ions into the cell via transport proteins
• Name an example of a reaction where the hydrolysis of ATP is coupled to provide energy.

  • The transmembrane sodium-potassium pump
• Describe the transmembrane sodium-potassium pump:

  • Energy is released from the hydrolysis of ATP
  • It pushes sodium ions out of the cell and potassium ions into the cell via transport proteins
• ATP is resynthesised by what type of reaction between ADP and Pi?

  Condensation reaction
• Hydrolysis of ATP releases energy. Resynthesis of ATP requires energy
• In Transcription:

  • The template strand of DNA is complementary to the base sequence of the target gene
  • The mRNA strand is complementary to the template strand and it is a copy of the base sequence of the target gene.
• What is the name of the first step of protein synthesis?

  Transcription
• What is the name of the second step of protein synthesis?

  Translation
• What is the site of protein synthesis?

  Ribosomes
• What is the genetic material in all living organisms made from?

  DNA
• Which molecule contains ribose? DNA or RNA?

  RNA
• Which organic base is NOT found in RNA?

  Thymine
• What is the name of the enzyme that accurately synthesises DNA during replication?

  DNA polymerase
• Which two groups are involved in the phosphodiester linkage?

  • 5' Phosphate
  • 3' Hydroxyl