DNA and ATP

• what are the 2 main types of nucleic acid

  1. deoxyribonucleic acid (DNA)

  
  

  2. ribonucleic acid (RNA)
• what is DNA

  genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals
• where is DNA

  - found in the nucleus of eukaryotes and in organelles

  = mitochondria + chloroplast

  
  

  - in prokaryotes, its found as a loop of DNA floating free in the cytoplasm
• what is RNA mostly involved in

  protein synthesis
• function of messenger RNA

  DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell
• what are the monomers of DNA and RNA

  nucleotides
• what are the polymers of nucleotides

  - DNA

  - RNA

  - polynucleotide
• what is a nucleotide made of

  - pentose sugar

  = 5 carbon sugar

  - phosphate group

  - nitrogenous base
• what is a deoxyribose

  pentose sugar in a dna nucleotide
• what are the 4 possible bases in DNA

  - adenine

  - thymine

  - cytosine

  - guanine

  = every DNA nucleotide has the same pentose sugar and phosphate group, but the base can vary
• what is ribose


  pentose sugar in a RNA nucleotide
• what are the 4 possible bases in RNA

  - adenine

  - cytosine

  - guanine

  - uracil

  = every RNA nucleotide has the same pentose sugar and phosphate group, but the base can vary
• difference between DNA and RNA

  DNA:

  
  

  - deoxyribose sugar

  - double stranded

  - thymine

  - longer

  
  

  RNA:

  
  

  - ribose sugar

  - single stranded

  - uracil

  - shorter
• similarities between RNA and DNA

  - nucleic acid

  - phosphate

  - adenine

  - guanine

  - cytosine
• who are the 2 scientists who proposed the chemical structure of DNA and DNA replication

  James Watson and Francis Crick

  = worked out the structure of DNA, following pioneering work by Rosalind Franklin on the X ray diffraction patterns of DNA
• what is DNA

  - polymer of nucleotides

  - each nucleotide is formed from a deoxyribose sugar, phosphate + nitrogenous base

  - phosphodiester bonds between nucleotides

  - double stranded which are held together by H bonds to form a double helix
• what are the complimentary bases

  - adenine + thymine

  = 2 H bonds

  
  

  - cytosine + guanine

  = 3 H bonds
• what's the rule with the amount of bases in a DNA molecule

  always equal amount of either adenine and thymine, + cytosine and guanine
• what bonding forms between the complimentary bases

  hydrogen bonds

  = they are weak so allow DNA to be separated so DNA replication + transcription can occur
• why is DNA having a double strand important

  each strand can act as a template in replication, a semi conservative process, meaning that DNA is copied accurately
• what are the 2 important features of DNA structure for DNA replication to occur

  - H bonds between complimentary bases

  - double stranded
• what is RNA


  relatively short, single polynucleotide chain

  = not a double one like DNA
• what are the 3 mains types of RNA

  1. messenger RNA - provides template for protein synthesis during translation

  
  

  2. transfer RNA - brings amino acids + reads the genetic code during translation

  
  

  3. ribosomal RNA - found in ribosomes, its plays structural + catalytic role
• what are pyrimidines

  single ring structures

  = thymine, cytosine, uracil
• what are purines

  double ring structures

  = adenine, guanine
• why are their complimentary bases

  purines (A, G) and pyrimidines (T, C, U) always link together due to shape/size
• what is a polynucleotide

  polymer of mononucleotides
• how are polynucleotides formed

  via a condensation reaction between the phosphate group of one nucleotide and the sugar of another

  = forms a phosphodiester bond
• what kind of bond is a phosphodiester bond

  strong, covalent bond

  = it consists of the phosphate group + 2 ester bonds
• what is a sugar phosphate backbone

  The chain of sugars and phosphates in a polynucleotide chain
• what happens when a polynucleotide is formed

  the 5' phosphate of the incoming nucleotide attaches to the 3' hydroxyl group at the end of the growing chain
• how does DNA form a double helix

  two antiparallel polynucleotide strands twist in opposite directions to form the DNA double helix
• how are antiparallel strands formed

  nucleotides are inverted 180 degrees

  = so 5' and 3' + 3' and 5' can join
• why does DNA replicate itself before cell division

  so that each new cell has the full amount of DNA
• what is semi conservation replication
• semi conservation DNA replication process

  1. the enzyme DNA helices breaks the hydrogen bonds between the base pairs on the 2 nucleotide DNA strands

  = this unwinds the helix to form 2 single strands

  
  

  2. each original single strand acts as a template for the new strand

  
  

  3. complimentary base pairing means that free floating DNA nucleotides are attracted to their base pair on the template strand

  = complimentary bases bond together by H bonds

  
  

  4. nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase

  = phosphodiester bonds are formed between adjacent nucleotides

  
  

  5. hydrogen bonds form between bases on the original + new strands

  
  

  6. each new DNA molecule contains one strand from the original DNA + one new strand
• what are Okazaki fragments
• what does the conservative model for DNA replication suggest

  - the original DNA molecule remained intact

  - a separate daughter DNA copy was built up from new molecules of deoxyribose, phosphate, + organic bases

  - of the 2 molecules produced, one will be made of entirely new material while the other would be entirely original material
• Meselson-Stahl Experiment (1958)


  - experiments with e coli first in heavy nitrogen (15N) then in the lighter isotope (14N)

  
  

  - DNA grown in 15N is heavier than DNA grown in 14N, + sediments to a lower level when spun in an ultracentrifuge

  
  

  - when DNA grown in 15N is switched to media containing 14N, after one round of cell division the DNA sediments halfway between the 15N + 14N levels

  = indicating that it now contains 50% 14N

  
  

  - the following cell divisions, an increasing amount of DNA contains 14N only

  = it contains 50% less 15N after each division

  
  

  - this data supports the semi conservative replication model

  
• what do all bases in DNA contain

  nitrogen