Nucleic acids

• There are two types of nucleic acids, what are they?

  ribonucleic acid (RNA)

  deoxyribonucleic acid (DNA)
• ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) are polymers of nucleotides (100s to 1000s) , which are the monomer units
• Roles of DNA

  *Protein expression (Phenotypes)

  *Inheritance (Genotypes)

  *Evolution (Mutations)
• Roles of RNA

  1. Used in protein synthesis
  2. Structural in ribosomes
• The amino acid sequence of a polypeptide is

  programmed by a gene

  A gene consists of a region of DNA

  DNA provides direction for its own replication

  DNA also directs RNA synthesis and through RNA,

  controls protein synthesis

  DNA (and its genes) is passed by the mechanisms of

  inheritance

  Is the only molecule that can produce identical copies

  of itself
• Nucleic acids store and transmit

  hereditary information
• Nucleotides

  • Polymers of

  nucleotides are called

  “strands” = nucleic acid

  • Each nucleotide

  consists of three parts:

  a nitrogen base

  a pentose sugar

  a phosphate group

  
• Pyrimidine Bases: Cytosine (C), Thymine (T), Uracil (U).
• Purine Bases: Adenine (A), Guanine (G).
• The nitrogen bases, rings of carbon and

  nitrogen, come in two types:

  purines

  pyrimidines
• Purines are the larger of the two types of bases

  found in DNA

  
• what base is this structure called?

  purine bases

  A) adenine

  B) guanine

  
• What base is this structure?

  Pyrimidine base

  A) cytosine

  B) thymine (in dna)

  C) Uracil (in RNa)

  
• Because nucleotide bases pairing shapes, only some bases are bonded with each other

  Purines always pair with pyrimidinesA with T (in RNA, A pairs with U)G with C
• what is this nucliotide base pair?

  Adenine and thymine (A and T)

  
• what is this nucleotide base pairing?

  Guanine and cytosine (G and C)

  
• building nucleic acid

  • Polynucleotides (nucleic

  acids) are connected by the

  sugar of each nucleotide

  • the hydroxyl group of one

  nucleotide is bonded to the

  phosphate of the next with a

  phosphodiester bond

  • The phosphodiester bonds

  create a repeating

  backbone of

  sugar-phosphate units with

  the nitrogen bases as

  ‘appendages’
• RNA is made by

  copying DNA

  and is used to

  make proteins

  Sugar is ribose

  It is a SINGLE

  strand of

  nucleotides

  
• DNA has a double helix structure with two strands that

  are antiparallel so that nucleotides can form hydrogen

  bonds
• Why H-bonds?

  In order to replicate, the strands

  must separate to make new

  DNA strands (cannot be broken

  if the strands were covalently

  bound)
• Pairs of nitrogenous bases, one from

  each strand, connect the polynucleotide

  chains with hydrogen bonds

  Most DNA molecules have thousands

  to millions of base pairs

  Sugar in nucleotides is deoxyribose
• The two strands of DNA are complementary
• What’s the difference between

  RNA and DNA?

  • An RNA molecule is single polynucleotide chain

  while DNA molecules have two polynucleotide

  strands that spiral around an imaginary axis to form

  a double helix

  • The pentose joined to the nitrogen base is ribose in

  nucleotides of RNA and deoxyribose in DNA

  • Nitrogen bases - thymine is replaced by uracil