nucleic acids

• two types of nucleic acid


  RNA and DNA
• DNA


  DeoxyriboseNucleicAcid
• RNA


  Ribose Nucleic Acid
• DNA and RNA 


  pentose monosaccharides
• 4 nitrogenous bases (DNA)

  -Adenine

  -Guanine

  -Thymine

  -Cytosine
• 4 nitrogenous bases (RNA)

  -Adenine

  -Guanine

  -Uracil

  -Cytosine
• DNA strands run anti-parallel to each other- one strand is upside down to the other
• when nucleotides join, they form a 5'-3' bond (in reference to the carbons on the sugar)
• purines

  -adenine

  -guanine
• pyrimidines

  -cytosine

  -thymine

  -uracil
• Adenine and Thymine are joined by 2 hydrogen bonds
• Guanine and Cytosine are joined by 3 hydrogen bonds
• RNA is single stranded, whereas DNA is double stranded
• ADP


  adenosine diphosphate- 2 phosphate groups with the adenine base
• ATP


  Adenosine Triphosphate. Made of 3 phosphate molecules
• ATP


  -molecule produced in cellular respiration

  -produced through a series of oxidation reactions where glucose is broken down

  -continually hydrolysed to ADP to release energy

  -can't be transported from cell to cell- must be used in the cell in which it is made.
• ATP


  -3 phosphate groups are joined together by high energy bonds

  -body needs ADP for muscle contraction, active transport and cell division
• hydrolysis of ATP to ADP


  -catalysed by ATPase

  -releases energy

  -inorganic phosphate molecule is also produced
• DNA replication occurs in interphase but mostly s-phase
• semi-conservative


  2 orginal 'parent' strands act as templates for formation of new strands. 1 old strand and 1 new strand
• meselson and stahl


  demonstrated that DNA replication is semi-conservative. form because of the complementary base rule
• gyrase


  unwinds unwinds the double helix
• helicase


  breaks the hydrogen bonds to separate the 2 strands
• what happens after helicase breaks the hydrogen bonds


  h bonds form between the free DNA nucleotides and the nucleotides of original strands according to the complementary base pairing theory
• DNA polymerase


  forms phosphodiester bonds between phosphate group of 1 nucleotide and the deoxyribose sugar of the next. it seals the sugar-phosphate backbone
• DNA polymerase limitations

  -only bonds to double stranded nucleic acids

  -only synthesis DNA in 5' to 3' direction
• point mutation


  1 in every 10^8 bases pair is wrongly inserted- wrong amino acid specified
• endonuclease


  proof-reading enzyme. cuts any wrongly paired bases to eliminate errors
• sugar-phosphate backbone is held together by phosphodiester bonds|
• how is ATP broken down to release energy


  -ATP hydrolase or ATP hydrolysis breaks down ATP into ADP
• ATP as a suitable energy source in living organisms

  -releases small amounts of energy

  -does not leave cells

  -can be broken down immediately
• what is atp?

  -universal energy currency in eukaryotic and prokaryotic cells

  -produced through a series of oxidation reactions

  -continually hydrolysed to adp to release energy and then resynthesised

  -can't be transported cell to cell
• ATP~

  -three phosphate groups joined by 2 high energy bonds

  -can be hydrolysed to ADP to release a large amount of energy

  -body needs ATP for muscle contraction, active transport and cell division
• hydrolysis of ATP to ADP

  -catalysed by ATPase

  -releases energy

  -one water molecule required

  -inorganic phosphate group is produced
• phosphorylated nucleotide

  -nucleotide with one or more phosphate groups added to it
• phosphorylation

  -in respiration, ADP is converted to ATP by adding a phosphate group

  -requires energy- bond is formed in a condensation reaction

  -catalysed by ATPsynthase
• polynucleotides

  -condensation reaction occurs between the phosphate group of one nucleotide and the sugar molecule of another to form a phosphodiester bond

  -"sugar- phosphate backbone"
• DNA replication

  -important so new cells have correct genes to function and synthesis the correct proteins

  -happens during interphase of the cell cycle
• semi- conservative

  -2 original parent strands of DNA act as templates for the formation of new strands

  -1 old strand and 1 new strand
• the bond made when nucleotides are polymerised are phosphodiester bonds