From Gene To Protein

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From Gene To Protein

• Meadowcreek High School Presentation
• October 18, 2006

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So Why Do We Care About Glucose?
C6H12O6 02 CO2 H2O ATP
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Insulin Overview

• Insulin - from Latin insula,
  "island
• Produced from b-islet cells of
  the pancreas
• Islets of Langerhans
• Discovered in 1869 by the German
  anatomist Paul Langerhans
• A protein hormone involved in carbohydrate
  homeostasis (sugar regulation)

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Insulin Overview
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DNA Overview

• What does DNA stand for?
• Deoxyribonucleic Acid
• Double helix
• Sugar-phosphate backbone
• Nitrogenous bases
• Adenine (A), Guanine (G), Cytosine (C), Thymine
  (T), Uracil RNA (U)
• Complimentary base pair rules
• A ? T (U) G ? C
• T ? A C ? G
• The genetic code
• A blueprint for protein

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Gene Transcription and Translation

• The process of going from a genetic language
  into a protein language
• What is a protein?
• A sequence of amino acids
• i.e. a protein is a polymer of amino acids the
  sequence of which defines the protein
• A two step process
• Gene transcription a mechanism whereby the gene
  sequence is copied onto another molecule (mRNA)
• Protein translation a mechanism whereby the
  gene sequence is translated into an amino acid
  sequence (i.e. a protein)

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• In a eukaryotic cell, transcription occurs in the
  nucleus, translation occurs in the cytoplasm.

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Gene Transcription
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• During transcription, the genetic code on DNA is
  copied (transcribed) onto a molecule of messenger
  RNA
• The messenger RNA is synthesized according to
  base-pairing rules.
• During translation, the
  genetic code is translated
  into a sequence of
  amino acids.
• Example-1
• Example-2

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The Genetic Code
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Insulin mRNA Sequence
auggccccgugg augcaucuccuc accgugcuggcc
cugcuggcccuc uggggacccaac ucuguucaggcc
uauuccagccag caccugugcggc uccaaccuagug
gaggcacuguac augacaugugga cggaguggcuuc
uauagaccccac gaccgccgagag cuggaggaccuc
cagguggagcag gcagaacugggu cuggaggcaggc
ggccugcagccu ucggcccuggag augauucugcag
aagcgcggcauu guggaucagugc uguaauaacauu
ugcacauuuaac cagcugcagaac uacugcaauguc ccuuag
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Insulin Amino Acid Sequence

• Met-Ala-Pro-Trp-Met-His-Leu-Leu-Thr-Val-Leu-Ala-Le
  u-Leu-Ala-Leu-Trp-Gly-Pro-Asn-Ser-Val-Gln-Ala-Tyr-
  Ser-Ser-Gln-His-Leu-Cys-Gly-Ser-Asn-Leu-Val-Glu-Al
  a-Leu-Tyr-Met-Thr-Cys-Gly-Arg-Ser-Gly-Phe-Tyr-Arg-
  Pro-His-Asp-Arg-Arg-Glu-Leu-Glu-Asp-Leu-Gln-Val-Gl
  u-Gln-Ala-Glu-Leu-Gly-Leu-Glu-Ala-Gly-Gly-Leu-Ala-
  Pro-Ser-Ala-Leu-Glu-Met-Ile-Leu-Gln-Lys-Arg-Gly-Il
  e-Val-Asp-Gln-Cys-Cys-Asn-Asn-Ile-Cys-Thr-Phe-Asn-
  Gln-Leu-Gln-Asn-Tyr-Cys-Asn-Val-Pro

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Insulin Amino Acid Sequence

• Met-Ala-Pro-Trp Met-His-Leu-Leu
• Thr-Val-Leu-Ala Leu-Leu-Ala-Leu
• Trp-Gly-Pro-Asn Ser-Val-Gln-Ala
• Tyr-Ser-Ser-Gln His-Leu-Cys-Gly
• Ser-Asn-Leu-Val Glu-Ala-Leu-Tyr
• Met-Thr-Cys-Gly Arg-Ser-Gly-Phe
• Tyr-Arg-Pro-His Asp-Arg-Arg-Glu
• Leu-Glu-Asp-Leu Gln-Val-Glu-Gln
• Ala-Glu-Leu-Gly Leu-Glu-Ala-Gly
• Gly-Leu-Ala-Pro Ser-Ala-Leu-Glu
• Met-Ile-Leu-Gln Lys-Arg-Gly-Ile
• Val-Asp-Gln-Cys Cys-Asn-Asn-Ile
• Cys-Thr-Phe-Asn Gln-Leu-Gln-Asn
• Tyr-Cys-Asn-Val Pro

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Mutations

• Mutations are changes in the genetic material of
  a cell.
• Point mutations are the most common - a chemical
  change in just one base pair in the gene.
• If these occur in gametes or cells producing
  gametes, they may be transmitted to future
  generations.
• i.e. an inherited disease

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Clinical Perspective Sickle-Cell Anemia

• A disease that affects the hemoglobin of red
  blood cells
• Oxygen transport protein
• Capacity to transport O2 (CO2) negatively
  effected leads to an anemic state
• RBCs also agglutinate leading to occlusion of
  blood vessels

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• Sickle-cell anemia
• Caused by a mutation of a single base pair in the
  gene that codes for one of the polypeptides
  (proteins) of hemoglobin.
• A change in a single nucleotide from T to A in
  the DNA template leads to an abnormal protein.

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• This is an example of a base-pair substitution.
• Types of mutations
• Missense mutation
• Mutation codes for wrong amino acid
• E.g. sickle cell anemia
• Nonsense mutation
• Mutation results in a stop codon
• Silent mutations
• Mutation undectable
• Mutation results in translation of same amino
  acid
• Mutation results in translation of similar amino
  acid
• Mutation results in translation of amino acid not
  essential for biological function

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Thank You