DNA and Genes

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DNA and Genes

• Modified Chapters 10, 11, 12

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DNA verse RNA.Review

• DNA and RNA are nucleic acids
• DNA genetic information
• RNA used to build proteins
• Built by nucleotides
• Can be single stranded or double stranded
• Bases
• Bonds

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DNA Replication

• Complete set of genetic instructions must pass
  from one generation to the next
• Begins at specific sites on a double helix
• Proceeds in both directions

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Overview
1. Strands separate a. New nucleotides
b. Result 2 DNA copies, each 1 new 1
old chain 2. DNA polymerase 3. Leading strand 4.
Lagging strand 5. Primer
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Flow of Genetic Information from DNA to RNA to
Protein

• Information contained in DNA is stored in blocks
  called genes
• genes code for proteins
• proteins determine what a cell will be like
• DNA stores information in nucleus
• instructions are copied from the DNA into
  messages comprised of RNA
• these messages are sent out into the cell
• direct the assembly of proteins

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Flow of Genetic Information from DNA to RNA to
Protein

• The path of information is often referred to as
  the central dogma
• DNA ? RNA ? protein
• Gene expression
• Transcription
• messenger RNA (mRNA) made from a gene within the
  DNA
• Translation
• Using the mRNA to direct the production of a
  protein

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Transcription

• Transcription
• Occurs in nucleus
• Genetic information transferred from DNA to RNA
• Important players
• RNA polymerase
• Ribosomal RNA (rRNA)
• Introns removed
• Exons spliced together

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Translation

• Occurs in cytoplasm
• Conversion from the nucleic acid language to the
  protein language
• Important players
• Messenger RNA (mRNA)
• mRNA is read in three-nucleotide units called
  codons
• Transfer RNA (tRNA)

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The genetic code (RNA codons)
There are 64 different codons in the genetic
code!!!!
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Genes gone bad

• Mutation
• Any change in the nucleotide sequence of DNA
• Can result in changes in the amino acids in
  proteins
• Often harmful, but are they always??
• Mutations may result from
• Errors in DNA replication
• Physical or chemical agents called mutagens

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Gene regulation
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How are Genes Regulated??

• In cellular differentiation
• Certain genes turned on and off
• Cells become specialized in structure and
  function
• In gene expression
• A gene is turned on and transcribed into RNA
• Information flows from genes to proteins,
  genotype to phenotype

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Bacteria

• Control sequences
• Stretches of DNA that coordinate gene expression
• An operon
• Cluster of genes with related functions,
  including the control sequences
• A promoter
• Control sequence
• Site where the transcription enzyme initiates
  transcription
• An operator
• DNA sequence between the promoter and the enzyme
  genes
• Acts as an on and off switch for the genes

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DNA Technology
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Cloning Plants and Animals

• Regeneration
• Regrowth of lost body parts in animals
• Nuclear transplantation
• Involves replacing nuclei of egg cells with
  nuclei from differentiated cells
• Has been used to clone a variety of animals
• Scottish researchers cloned the first mammal in
  1997
• Dolly!!
• Reproductive cloning

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Recombinant DNA Technology

• Set of techniques for combining genes from
  different sources into a single DNA molecule
• genetically modified (GM) organism
• organism that carries recombinant DNA
• Recombinant DNA technology is applied in the
  field of biotechnology
• Biotechnology uses various organisms to perform
  practical tasks

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Genetically Modified (GM) Foods

• Replacing traditional plant-breeding programs
• Corn has been genetically modified to resist
  insect infestation

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Recombinant DNA Techniques

• Bacteria.
• To work with genes in the laboratory, biologists
  often use bacterial plasmids
• Small, circular DNA molecules

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Recombinant DNA Techniques

• Plasmids
• Can easily incorporate foreign DNA
• Readily taken up by bacterial cells
• Act as vectors
• DNA carriers that move genes from one cell to
  another
• Can help biologists produce large quantities of a
  desired protein

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Cutting and Pasting DNA with Restriction Enzymes

• To combine the plasmid and gene
• piece of DNA must be spliced into a plasmid
• Accomplished using restriction enzymes
• cut DNA at specific nucleotide sequences
• cuts produce pieces of DNA called restriction
  fragments
• May have sticky ends that are important for
  joining DNA from different sources

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Transformation of Insulin Gene

• human insulin gene isolated and cut from its
  location on the human chromosome
• using a restriction enzyme
• plasmid is cut using the same restriction enzyme
• desired DNA (insulin gene) and plasmid DNA can be
  joined using DNA ligase
• plasmid now contains the genetic instructions on
  how to produce the protein insulin
• Bacteria can be artificially induced to take up
  the recombinant DNA plasmids and be transformed
• successfully transformed bacteria will contain
  the desired insulin gene
• transformed bacteria containing the insulin gene
  can be isolated and grown
• As transformed bacteria grow they will produce
  the insulin proteins coded for the recombinant
  DNA
• Insulin harvested and used to treat diabetes

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DNA Fingerprinting and Forensic Science

• DNA technology has rapidly revolutionized the
  field of forensics
• scientific analysis of evidence from crime scenes
• Uses
• Paternity
• Victim identification
• Crimes
• Evolutionary research
• Study ancient pieces of DNA
• Cheddar Man!!!!

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Genetic testing
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The Polymerase Chain Reaction (PCR)

• Technique by which any segment of DNA can be
  copied quickly and precisely
• Scientists can obtain enough DNA from even minute
  amounts of blood or other tissue to allow DNA
  fingerprinting

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Gel Electrophoresis

• Used to separate the DNA fragments obtained from
  different sources
• The DNA fragments are visualized as bands on
  the gel
• The bands of different DNA samples can then be
  compared

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Cases
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The Human Genome Project

• Joint project of National Institute of Health
  (NIH) and Department of Energy (DOE)
• Now an international effort
• What is DNA sequencing?
• process of determining the exact order of the
  3164.7 million chemical nucleotide bases that
  make up the DNA of the 24 different human
  chromosomes
• How do they do it?
• For details on the procedure, check out
  http//www.ornl.gov/hgmis/project/info.htmlhow
• Proposed 1990 15-year time frame

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Some Goals of the Human Genome Project

• identify all the approximately 30,000 genes in
  human DNA
• determine the sequences of the 3 billion chemical
  base pairs that make up human DNA
• store this information in databases
• improve tools for data analysis
• transfer related technologies to the private
  sector

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Ethical Issues of Human Genome Project

• Privacy of Genetic Information Who gets to know?
• Mates/spouses
• Insurance companies
• Employers
• Testing for Diseases Do you want to know? What
  now?
• Prenatal testing
• Diseases with no cure/treatment

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Tracking the Anthrax Killer

• In October 2001, Florida man died from inhalation
  anthrax
• By the end of the year, four other people had
  also died from anthrax
• Investigators analyzed the genome of the anthrax
  spores used in each attack
• Able to establish that the spores from all of the
  cases were identical
• Suggested a single perpetrator of the crime
• Able to match the anthrax with one laboratory
  subtype
• The Ames strain

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Human Gene Therapy

• recombinant DNA procedure that seeks to treat
  disease by altering the genes of the afflicted
  person
• The mutant version of a gene is replaced or
  supplemented with a properly functioning one

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Conviction

• Betty Anne Waters
• Ayer, MA
• 1982 brother arrested for murder
• Waters went to CCRI
• GED
• Associates
• Went to Roger Williams to get Bachelors and Law
  degree
• Became brothers lawyer
• Witnesses lied
• DNA evidence in 1990s
• Innocence Project
• Released in 2001 after serving 18 years in prison
• 3.4 million dollar settlement

http//www.imdb.com/video/imdb/vi4273341977/