Biochemistry: Nucleic Acids

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Biochemistry Nucleic Acids

• November 3, 2007
• Bio099
• Timberlake Chapter 17
• Martinin Pages 54-55

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Nucleic Acids The Big Picture
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Two Types of Nucleic Acids

• Two Types
• DNA
• Deoxyribonucleic acid

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Two Types of Nucleic Acids

• Two Types
• DNA
• Deoxyribonucleic acid
• RNA
• Ribonucleic acid

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NucleotideThe monomer of nucleic acids
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Molecular Components of the nucleotide

• Pentose sugar

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Molecular Components of the nucleotide

• Pentose sugar
• Phosphate group

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Molecular Components of the nucleotide

• Pentose sugar
• Phosphate group
• Nitrogenous bases
• purine pyrimidine

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Nitrogenous Bases
BASES OF DNA
BASES OF RNA
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Nucleoside
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Primary Structure of Nucleic Acids

• Nucleotides are bound together to form nucleic
  acids.

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Primary Structure of Nucleic Acids

• Nucleotides are bound together to form nucleic
  acids.
• The sequence of bases is like an instruction
  manual that can be read by the cell.

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Secondary Structure of Nucleic Acids

• DNA
• The Double Helix
• The vertical blue strand represents the sugar
  and phosphate group and the inner horizontal
  bands represent the nitrogenous bases

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Secondary Structure of Nucleic Acids

• DNA
• The Double Helix
• Complementary base pairs

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Secondary Structure of Nucleic Acids

• DNA
• The Double Helix
• Complementary base pairs
• Helical

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Secondary Structure of Nucleic Acids

• RNA
• Single stranded, but loopy in structure

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DNA Replication

• Each time a cell divides, its entire genome must
  be copied and passed on to the new cell.

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DNA Replication

• 1 double helix replicates to give 2 new double
  helixes

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DNA Replication

• 1 double helix replicates to give 2 new double
  helixes
• The 2 new DNA molecules are made of 1 OLD and 1
  NEW polynucleotide strands

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The Steps of DNA Replication

• The two DNA strands are unwound with the help of
  the enzyme HELICASE which facilitates the
  breaking of the chemical bonds between the
  molecules.

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The Steps of DNA Replication

• DNA POLYMERASE helps to form bonds between the
  nucleotides of the newly formed strand.

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Protein SynthesisThe Big Picture

• DNA
• (instructions)
• RNA
• (copy of instructions)
• Protein
• (result of following instructions)

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Protein Synthesis requires 3 types of RNA

• DNA
• RNA
• Protein

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Three Types of RNA

• messenger RNA (mRNA)
• copy of a gene (DNA)
• leaves nucleus
• to carry genetic
• information to
• the ribosome for
• protein synthesis

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Three Types of RNA

• ribosomal RNA (rRNA)
• part of the ribosome

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Three Types of RNA

• transfer RNA (tRNA)
• transfers the amino acids
• to the ribosome for
• protein synthesis.

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Steps of Protein Synthesis

• Transcription of the genetic material.
• making the mRNA.

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Steps of Protein Synthesis

• The mRNA travels to the cytoplasm.

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Steps of Protein Synthesis

• Translation of the mRNA
• The word translation is used because the language
  is changing from nucleic acids to amino acids.
• A genetic code is used by the cell to translate
  the genetic material (mRNA) into a protein
• 3 nucleotides of mRNA make a codon
• that translates to a specific amino
  acid,
• or a start or stop message during
• protein synthesis.

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Steps of Protein Synthesis

• Translation of the mRNA is initiated with a start
  codon.

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Steps of Protein Synthesis

• Translation of the genetic material continues
  and the polypeptide gets longer.

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Steps of Protein Synthesis

• Termination occurs when a stop codon is reached.

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Genetic Mutations

• Mutations are changes in the sequence of
  nucleotides in DNA.
• Mutations within a gene can alter the sequence of
  amino acids in a protein causing changes, or lack
  of protein function.

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Types of Mutations

• Substitution

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Types of Mutations

• Substitution

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Types of Mutations

• Frameshift

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Genetic Mutations and Disease

• A mutation in the gene that encodes the protein
  leptin leads to marked obesity in rodents and
  humans.

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Genetic Diseases

• For more examples of genetic diseases caused by
  mutations see Timberlake Table 17.5