Nucleic Acid

• What type of reaction joins nucleotides together and what molecules will be formed?

  • Condensation reaction
  • Phosphodiester bond (pentose sugar and phsophate group)
• What bases are purines?

  -Adenine

  -Guanine

  >larger
• What bases are pyramidines?

  • Thymine
  • Cytosine
  • >smaller
• What are features in chain of DNA?

  • The chains are anti-parallel that is the 3' end of one chain lies next to the 5' end of the other
• What are the types the RNA?

  • tRNA (transfer)
  • mRNA (messanger)
  • rRNA (ribosomal)
• What is semi conservative replication?

  DNA replication where each new DNA molecule consists of one original strand and one newly synthesized strand.
• What does degenerate mean?

  • Usually more than codon that codes for each amino acid
• What does non-overlapping mean?

  • Each base sequence is only read once
• What does universal mean?

  • The same codes for the same amino acid in all organisms
• What is transcription?

  • Transcription is the name of the process in which a copy DNA is made
  • The copy is known as mRNA
• What happens in transcription?

  • DNA double helix unzips as helicase breaks H bonds between complementary bases
  • The two nucleotide strands separate
  • One strand acts as a template,free RNA nucleotides complementary base pair to exposed bases on the strand forming H bonds (no T)
  • RNA polymerase forms sugar-phosphate bonds between nucleotides
  • The mRNA detatches from template strand
  • The 2 DNA strands join back together through complementary base pairing
  • The DNA winds back up into helix
  • mRNA has the same sequence of bases as coding strand
• What is the first step of translation?

  The ribosome attaches to the mRNA strand
• What codon does the ribosome attach to at the start of translation?

  The start codon AUG
• What does the tRNA molecule carry during translation?

  A specific amino acid
• What is the role of the anticodon in tRNA?

  It is complementary to the mRNA codon
• What happens after the first tRNA molecule binds to mRNA?

  A second tRNA molecule attaches to mRNA
• How does the second tRNA molecule bind to mRNA?

  With an anticodon complementary to the next codon
• What type of bond links the amino acids carried by tRNA molecules?

  A peptide bond
• What energy molecule is used to form peptide bonds?

  ATP
• What happens to the first tRNA molecule after the peptide bond is formed?

  It detaches from mRNA
• What occurs as the ribosome moves along the mRNA strand?

  Another tRNA molecule binds to the next codon
• How is the polypeptide chain elongated during translation?

  By repeating steps 4 to 6
• How many tRNA molecules can be attached to the ribosome at once?

  Two tRNA molecules
• What signals the end of the translation process?

  The ribosome reaches a stop codon
• What happens to the completed polypeptide chain at the end of translation?

  It detaches from the ribosome
• What is translation?

  Process of decoding the information in messanger RNA to synthesise a polypeptide chain with the help of tRNA
• Where does translation occur?

  Occurs in the cytoplasm specifically on the ribosome
• Where does transcription occur?

  Transcription occurs in the nucleus but only in eukaryotic cells
• What are some features of mRNA?

  • Single stranded,linear model
  • Contains a base sequence complementary to a DNA
  • Contains codons
  • Small enough to leave the nucleus
• What are some features of tRNA?

  • Single stranded molecule folded into a clover leaf shape
  • Uses hydrogen bonding between complementary base pairs to hold it in shape
  • Contains a specific sequences of 3 bases at one end-known as an anti codon
  • Contains an amino acid binding site at the opposite end
• What does ATP consist of?

  • Adenine
  • Ribose
  • Phosphates
• What are some uses for ATP in the body?

  • Movement
  • Active transport against the concentration gradient
  • Synthesis of large molecules
  • Secretion of substances from cells

  ATP can also activate molecules by phosphorylating them.When ATP is hydrolysised, the phosphate can be added to another molecule
• What are ATP's reactions?

  • Hydrolysis
  • Condensation

  ATP is broken down by hydrolysis and re-synthesised using a condensation reaction
• ATP functions:

  1. The hydrolysis of ATP releases a small amount of energy, meaning little energy is lost as heat.
  2. ATP is broken down in one step, meaning energy is released quickly.
  3. ATP is rapidly re-synthesised so that ATP is always readily available.
  4. The inorganic phosphate from ATP hydrolysis can phosphorylate other compounds, which makes them more reactive.
  5. The bonds between the phosphate groups are unstable, have a low activation energy and are easily broken.
  6. ATP is soluble, so it can easily be transported around cells.