Nucleic acids

• ATP hydrolase

  An enzyme which catalyses the hydrolysis of ATP into ADP and Pi
• semi-conservative replication


  Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand
• What did Meselson and Stahl discover?

  DNA replication is semi-conservative
• What are ribosomes made of?

  rRNA and proteins
• What forms the backbone of DNA?

  deoxyribose sugar and phosphate groups
• why is the sequence of bases important

  they determine which amino acids are used to form the protein
• why is the amino acid sequence important

  it determines which protein is made
• what is the structure of a tRNA molecule


  one end has a amino acid attached, the other end has an anti-codon

  
• where does translation occur

  in the cytoplasm, at a ribosome
• where does transcription occur

  inside the nucleus
• what occurs during translation


  at one end of the tRNA molecule is a trio of nucleotide bases that attaches to a specific amino acid

  at the other end is another triplet of bases, called an anticodon, that is complementary to a specific codon of bases on the mRNA strand

  tRNA molecules bring the amino acids to the ribosome, where the anticodon binds (by hydrogen bonding) to the complementary codon on the mRNA molecule
• what does RNA polymerase do

  catalyses the formation of temporary hydrogen bonds between RNA nucleotides and their complementary, unpaired DNA bases on the template strand
• what occurs during transcription

  the hydrogen bonds between the bases in DNA break, and the gene unzips

  temporary hydrogen bonds between RNA nucleotides and their complementary, unpaired DNA bases on the template strand form

  this newly formed mRNA leaves the nucleus

  the hydrogen bonds reform between the bases to remake the helix shape
• what are the two main stages of the synthesis of polypeptides

  transcription then translation
• why is the universal code described as degenerate


  some amino acids are coded for by more than one triplet
• why is the universal code described as non-overlapping

  the triplets are read from fixed points
• why is the universal code described as using triplets

  three consecutive bases (triplets) code for one amino acid
• why is the universal code described as universal

  all organisms use the genetic code in the same way to make proteins
• why are mutations described as random and spontaneous

  it cannot be predicted where or when they will occur
• why is DNA replication known as semi-conservative

  half of the product is the original genetic code, the other half is new
• whats the process of DNA replication

  one double stranded molecule untwists and the hydrogen bonds between the base pairs breaks leaving exposed bases

  complementary base pairing occurs between free nucleotides and the exposed bases
• what are exposed bases

  after being unzipped, the nitrogenous bases are free to be bonded to
• what does DNA polymerase do

  joins the free nucleotide bases to the exposed bases
• what does DNA helicase do

  breaks the hydrogen bonds between the base pairs
• what does DNA gyrase do

  helps the DNA molecule unwind
• what enzymes are used during DNA replication

  DNA gyrase, DNA helicase, DNA polymerase
• what is the purpose of DNA replication

  in order to copy their DNA for biological inheritance
• what steps are required to extract DNA and why

  1) grind to break open the cell wall

  2) add a strong detergent to release the DNA

  3) add ethanol so the DNA precipitates out
• what bond joins two nucleotides, and in what reaction is this bond formed

  phosphodiester bonds are formed in condensation reactions
• Why is DNA described as antiparallel?


  one strand begins 3' and ends 5'

  the other strand is the opposite, they travel in opposite directions

  
• what base does A, T, C and G bind to and how

  A binds to T with two hydrogen bonds

  C bind to G with three hydrogen bonds
• what is the structure of ATP

  same as a nucleotide, but with three phosphate groups

  
• what are phosphorylated nucleotides, give two examples

  nucleotides with more than one phosphate group

  eg. ATP, ADP
• what is the relationship between purine and pyrimidine bases

  a purine base can only pair with a pyrimidine base
• what is a pyrimidine base, and what bases are pyrimidine

  a pyrimidine base has one ring

  eg. adenine and guanine
• what is a purine base, and what bases are purine

  a purine base has two rings

  eg. thymine and cytosine
• three differences between DNA and RNA

  DNA: long

  RNA: short

  
  

  DNA: double stranded

  RNA: single stranded

  
  

  DNA: thymine

  RNA: uracil
• what is the function of mRNA, tRNA and rRNA

  mRNA: carries the code held in the genes to the ribosomes

  tRNA: transports amino acids to the ribosomes

  rRNA: makes up ribosomes
• what does RNA stand for, and how many types of RNA are there

  ribonucleic acid

  tRNA

  mRNA

  rRNA
• what does DNA stand for

  deoxyribonucleic acid