Nucleic acids

• What are the 2 types of nucleic acids?

  DNA and RNA (Deoxyribonucleic acid and ribonucleic acid)
• What are the monomers called for nucleic acids?

  Nucleotides
• What are the Polymers called for nucleotides?

  Polynucleotides (DNA and RNA)
• DNA and RNA nucleotide

  A) Phosphate

  B) Nitrogenous base

  C) Pentose sugar

  
• What are the 4 nitrogenous bases?

  Adenine, Thymine, Guanine, Cytosine
• how do the nitrogenous bases pair?

  Adenine = Thymine, Cytosine = Guanine
• What are purines?

  Nitrogenous bases with a double ring structure, found in DNA and RNA, including adenine and guanine.
• What are pyrimidines?

  Pyrimidines are a type of nitrogenous base with a single ring structure, found in DNA and RNA, including cytosine and guanine.
• What are the types of reactions that form and break polynucleotide chains?

  Formation: Condensation Breaking: Hydrolysis
• 3 hydrogen bonds hold the Pyrimidines together (single ring structure) and 2 hydrogen bonds hold the Purines together (double ring structure)

  
• Polynucleotide chain in the context of the double helix

  
• In DNA the % of guanine is 10% so what is the content of adenine?

  G=C so C= 90% therefore Thymine and Adenine are 90%
• What replaces Thymine in RNA?

  Uracil
• Uracil is a purine base in RNA.
• What are the 3 types of RNA?

  1. mRNA - messenger RNA
  2. rRNA - ribosomal RNA
  3. tRNA - transport RNA
• What is the function of mRNA?

  To carry the genetic information from DNA to the ribosomes in the cytoplasm, where it serves as a template for protein synthesis.
• What is the function of rRNA?

  The synthesis of proteins in cells.
• What is the function of tRNA?

  To bring amino acids to the ribosome during protein synthesis, ensuring that the correct sequence of amino acids is incorporated into the growing polypeptide chain.
• Comparisons between DNA and RNA

  A) 2

  B) 1

  C) Deoxyribose

  D) Ribose

  E) T

  F) Uracil

  G) 24

  H) 3

  I) Cytoplasm

  J) Chromosomes

  K) Long

  L) Short

  M) 521

  N) 3

  O) Carries

  P) Copies

  
• What are the 4 requirements for semi-conservative replication to take place?

  1. Nucleotides must be present
  2. Both strands of DNA act as a template
  3. The enzymes DNA polymerase and DNA helicase must be present
  4. Source of energy is required to drive the process
• Give one advantage of a DNA molecules having 2 strands

  Protects bases
• Semi-conservative DNA replication stages

  1. DNA helicase breaks the hydrogen bonds between bases on the 2 polynucleotide DNA strands, helix unwinds
  2. Original strand acts as a template for new strand, complementary bases pair with the base on template strand,
  3. DNA polymerase joins nucleotides together in a condensation reaction forming a phosphodiester bond.
• What bond forms between 2 nucleotides

  Phosphodiester bond

  
• DNA has antiparallel nature with a 5' and 3' end.
• DNA polymerase is only complementary to 3' end, so it can only add new nucleotides to new strand at 3' end.
• DNA polymerase only moves from 5' to 3' direction during DNA replication, this means there is a lagging strand which moves in smaller chunks behind the continuous strand.

  A) Lagging strand

  B) Continuous strand

  
• How is prokaryotic DNA different to eukaryotic DNA?

  1. Prokaryotic DNA is circular
  2. Prokaryotic DNA does not form chromosomes
• Evidence for semi-conservative replication

  Meselson-Stahl used heavy nitrogen (N15) and light nitrogen (N14) on E.coli (which divides every 20 minutes) and spun in a centrifuge to see what percentage of the DNA contained N15 and N14 at each generation.