RNA AND PROTEIN SYNTHESIS

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RNA AND PROTEIN SYNTHESIS

• RNA vs DNA
• RNA DNA
• 1. 5 Carbon sugar (ribose) 5 Carbon sugar
  (deoxyribose)
• 2. Phosphate group Phosphate group
• 3. Nitrogenous base Nitrogenous base
• 4. Single stranded Double stranded
• 5. Uracil base Thymine base

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RNA MOLECULE
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TYPES OF RNA

• Messenger RNA (mRNA)
• Carries copies of instructions for
• the assembly of amino acids
• into proteins from DNA to the rest
• of the cell
• Ribosomal RNA (rRNA)
• Makes of the major part of a ribosome
• Transfer RNA (tRNA)
• Transfers amino acids to ribosomes
• during protein synthesis

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TRANSCRIPTION

• Transcription
• ? The process of producing
• RNA molecules by copying
• part of the nucleotide
• sequence of DNA into a
• complementary sequence
• in RNA
• ? Requires the enzyme
• RNA polymerase
• Binds to and separates the
• DNA strands
• Uses one strand of DNA as a
• template to form RNA
• Binds to regions of DNA known
• as promoters which have
• specific base sequences
• Promoters are signals in DNA
• that indicate to the enzyme
• where to start and stop making

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GENE coded DNA instructions that control the
production of proteins in the cell
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RNA Editing

• RNA molecules have sections called
• Introns sections not coded for
• making proteins
• ? cut out or edited while still in
• the nucleus
• Exons sections coded for making
• proteins
• ? spliced back together to form
• final mRNA

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THE GENETIC CODE

• The Genetic Code
• The language of mRNA instructions
• Consist of 20 different amino acids
• With 64 possible codons
• ? Codon consist of 3 consecutive
  nucleotides that specify a specific amino acid (3
  bases long)
• ? Proteins are made by joining
• amino acids into long chains
• called polypeptides
• The property of a protein is determined by the
  order in which different amino acids are joined
  together to form polypeptides

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TRANSLATION

• Translation
• ? The decoding of an mRNA message into a
  polypeptide chain
• (protein)
• ? Takes place on ribosomes in the cytoplasm
• Begins when mRNA in the cytoplasm attaches to a
  ribosome
• Each codon of the mRNA moves through the ribosome
• Proper amino acid is brought into the ribosome by
  tRNA
• Amino acid is transferred to growing polypeptide
  chain in the ribosome
• Each tRNA carries only one kind of amino acid
• Each tRNA has 3 unpaired bases called anticodons
  which are
• complementary to one mRNA codon
• Works like an assembly line
• Polypeptide chain continues to grow until the
  ribosome reaches a stop codon
• Polypeptide chain is released ? Protein

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TRANSLATION
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PROTEIN SYNTHESIS
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PROTEINS

• Protein
• ? Enzymes that catalyze and regulate
  chemical reactions
• ? Act as microscopic tools to build or
  operate a component of a living
• cell
• ? Genes code for proteins that in turn
  determine genetic traits

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MUTATIONS
MUTATIONS

• Mutation
• Changes in the genetic material
• Effect on organism
• ? Most effects are neutral
• ? Some effects are deadly
• ? Some lead to greater genetic variability in a
  species
• Causes
• ? Random mistakes during DNA replication or RNA
  transcription
• ? Prolonged exposure to excessive radiation or
  harmful chemicals
• Types of Mutations
• ? Point mutation gene mutations involving
  changes in one or a few
• 
  nucleotides
• Occur at a single point in the DNA sequence
• Include substitutions, insertions and deletions
• ? Substitution one base is changed to another
• ? Insertions base is inserted into the DNA
  sequence
• ? Deletion Base is deleted from the DNA
  sequence

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• ? Frameshift mutation mutations that
  shift the reading frame of
• 
  the genetic message by inserting or
• 
  deleting a nucleotide
• May change every amino acid that follows the
  point of mutation
• Protein may be altered so much that it is
  unable to perform its normal function
• May lead to termination of organism (death)
• ? Chromosomal mutation involves changes
  in the number or
• 
  structure of chromosomes
• May change the locations of genes on
  chromosomes
• DELETIONS involve the loss or all or part of
  a chromosome
• DUPLICATION produce extra copies of parts of
  a chromosome
• INVERSION reverse the direction of parts of a
  chromosome
• TRANSLOCATION part of one chromosome breaks
  off and attaches to another
• Significance of Mutations
• ? Most are neutral
• ? Some are harmful
• Causes of genetic disorders
• Causes of many types of cancer

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