What must DNA do?

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What must DNA do?

1. Replicate to be passed on to the next generation
2. Store information
3. Undergo mutations to provide genetic diversity

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DNA structure A review

• Double-stranded helix
• Composed of repeating nucleotides (made of a
  pentose sugar, phosphate and a nitrogenous base)
• Sugar and phosphate make up the backbone while
  the bases make up the rungs of the ladder
• Bases have complementary pairing with cytosine
  (C) pairs with guanine (G) and adenine (A) pairs
  with thymine (T)

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DNA structure
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How does DNA replicate?

• The two strands unwind by breaking the H bonds
• Complementary nucleotides are added to each
  strand by DNA polymerase
• Each new double-stranded helix is made of one new
  strand and one old strand (semiconservative
  replication)
• The sequence of bases makes each individual unique

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DNA replication
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Check out the Animation!

• http//www.dnai.org/a/index.html

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RNA structure and function

• Single-stranded
• Composed of repeating nucleotides
• Sugar-phosphate backbone
• Bases are A, C, G and uracil (U)
• Three types of RNA
• Ribosomal (rRNA) joins with proteins to form
  ribosomes
• Messenger (mRNA) carries genetic information
  from DNA to the ribosomes
• Transfer (tRNA) transfers amino acids to a
  ribosome where they are added to a forming
  protein

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RNA structure
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Sum It Up!!!

• Make a Venn Diagram in your notes to compare and
  contrast DNA and RNA.

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Comparing DNA and RNA

• Similarities
• Are nucleic acids
• Are made of nucleotides
• Have sugar-phosphate backbones
• Are found in the nucleus

• Differences
• DNA is double stranded while RNA is single
  stranded
• DNA has T while RNA has U
• RNA is also found in the cytoplasm as well as the
  nucleus while DNA is not

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Proteins A review

• Composed of subunits of amino acids
• Sequence of amino acids determines the shape of
  the protein
• Synthesized at the ribosomes
• Important for diverse functions in the body
  including hormones, enzymes and transport
• Can denature causing a loss of function

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Proteins A review of structure
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2 steps of gene expression

• Transcription DNA is read to make a mRNA in the
  nucleus of our cells
• Translation Reading the mRNA to make a protein
  in the cytoplasm

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Check out the Animation!

• http//www.dnai.org/a/index.html

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Overview of transcription and translation
Bio
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Check out the Animation!

• http//www.dnai.org/a/index.html

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The genetic code

• Made of 4 bases
• Bases act as a code for amino acids in
  translation
• Every 3 bases on the mRNA is called a codon that
  codes for a particular amino acid in translation

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What did we learn from the human genome project
(HGP)?

• Humans consist of about 3 billion bases and
  25,000 genes
• Human genome sequenced in 2003
• There are many polymorphisms or small regions of
  DNA that vary among individuals were identified
• Genome size is not correlated with the number of
  genes or complexity of the organisms

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What is the next step in the HGP?

• Functional genomics
• Understanding how the 25,000 genes function
• Understanding the function of gene deserts (82
  regions that make up 3 of the genome lacking
  identifiable genes)
• Comparative genomics
• Help understand how species have evolved
• Comparing genomes may help identify base
  sequences that cause human illness
• Help in our understanding of gene regulation

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How can we modify a persons genome?

• Gene therapy - insertion of genetic material
  into human cells to treat a disorder
• Ex vivo therapy cells are removed for a person
  altered and then returned to the patient
• In vivo therapy a gene is directly inserted
  into an individual through a vector (e.g.
  viruses) or directly injected to replace mutated
  genes or to restore normal controls over gene
  activity
• Gene therapy has been most successful in treating
  cancer

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Ex vivo gene therapy
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DNA technology terms

• Genetic engineering altering DNA in bacteria,
  viruses, plants and animal cells through
  recombinant DNA techonology
• Recombinant DNA contains DNA from 2 or more
  different sources
• Transgenic organisms organisms that have a
  foreign gene inserted into them
• Biotechnology using natural biological systems
  to create a product or to achieve an end desired
  by humans