Microbiology Chapter 9

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Microbiology Chapter 9

• Genetics - Science of the study of heredity,
  variations in organisms that are transferable
  from generations to generation
• DNA is the key to understanding genetics, DNA is
  the genetic material of life and the
  macromolecule is responsible for storing all the
  information necessary to the function of an
  organism
• Genes units of heredity, segments of DNA they
  code for functional products (proteins) these
  products, cause something synthesis of
  pigments, enzymes etc. Result in some observable
  trait
• Genome is the total genetic information in a cell
  (all of the potential information, coded in the
  total DNA)

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Microbiology Chapter 9

• DNA double helix, two strands held together by
  Hydrogen bonds

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Microbiology Chapter 9

• Chromosome structures that carry the DNA
  (genes), often in Eukaryotic organisms there is
  protein associated with the genes. Chromosomes -
  can have many linear ones as in the eukaryotic
  cells. Single and circular chromosomes in
  bacteria
• Plasmids bacteria can have an extra piece of
  genetic information separate from the chromosome
  (extrachromosomal DNA)

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Microbiology Chapter 9
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Microbiology Chapter 9

• Genotype the genetic make up of an organism,
  sum total of all the information (expressed and
  unexpressed)
• Phenotype the actual expressed information
  (what you can see or detect)
• color of a colony, abilities to ferment sugars,
  etc.

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Microbiology Chapter 9

• Serratia marcesens temp. dependent colony
  pigment, genotype for pigment, cooler temp. than
  37 to see it Phenotype

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Microbiology Chapter 9

• Structure of DNA - its chemical make up
  (transparency of pg 251)
• 3 parts 5 carbon sugar (deoxyribose), a
  nitrogenous base, and a phosphate
• 1. Together they form what we call a nucleotide
• 2. There are four bases so there are four
  possible nucleotides
• 3. These are adenine, guanine, cytosine, thymine
  (A,G,C,T)
• 4. These nucleotides are combined to form long
  chains
• 5. In DNA the chains are paired into a ladder
  like double helix
• 6. The bases on one chain pair with bases on the
  corresponding chain by weak hydrogen bonds (A-T
  and G-C)

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Microbiology Chapter 9

• DNA double helix, two strands held together by
  Hydrogen bonds

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Microbiology Chapter 9

• BE SURE TO LOOK OVER FIG. 9.5 PG 252.
  9.6, pg 254 Go to web and view the animation on
  Mcgraw-Hill web site Slide 13
• DNA replication the process of making an exact
  copy of DNA molecule
• DNA replication has to occur before cell
  division in order for each cell to have a copy of
  
• the genetic information
• One strand of DNA acts as template for the
  formation of the corresponding strand
• 2. Replication is carried out in an orderly
  sequence
• a. It is biosynthesis, making macromolecules
  from smaller nucleotide subunits
• b. ATP is used to drive this biosynthesis
  process
• 3. Replication starts by unwinding of the double
  helix and the two strands separate exposing the
  now unpaired nitrogenous bases
• a. The two strands act as templates for the
  formation of the other strand

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Microbiology Chapter 9

• DNA replication

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Microbiology Chapter 9

• b. Specific enzymes are required and of course
  the precursor molecules must be available
• c. The most important enzyme is DNA polymerase
• d. The enzyme cause bonds to form and new chains
  are formed everywhere on the parent strand an
  adenine appears, a thymine will be linked to form
  the compliment on the forming daughter strand
  (see page 252, 254)
• e. Note that the forming strands are linked by
  joining phosphate of one nucleotide monomer with
  the OH of the other (note the nucleoside has a
  tri-phosphate and two phosphates are removed when
  one nucleoside is joined to the other)
• f. Each chain has a 3 end and 5 end (pg 254)
  lots of detail and we cant begin to cover it all

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Microbiology Chapter 9

• Remember
• Helicase
• DNA polymerase - one on leading strand,
  continuous
• DNA polymerase - one on lagging strand,
  discontinuous
• Requires Ligase to stitch the pieces together
• We will see it in animation on the DNA video

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Fig. 9.5
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Microbiology Chapter 9

• Transcription PG. 259 The assembly of a
  complimentary mRNA strand from a DNA template
• (remember there are 3 kinds of RNA mRNA, rRNA,
  tRNA)
• Messenger RNA carries a message to site of
  protein synthesis make a chain of amino acids
  with this specific sequence
• 2. Transfer rRNA is involved in protein
  synthesis, it carries the amino acids to the
  ribosome where they are assembled (SEE PG. 258,
  260, 262)
• 3. Ribosomal RNA forms the ribosome unit where
  proteins are assembled
• DNA codes for a specific messenger RNA with a
  specific sequence of nucleotide bases
• (RNA has ribose, and the bases are adenine,
  guanine, cytosine, and uracil) A pairs with U and
  of course G pairs with C, (A-U, G-C)

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Microbiology Chapter 9
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Fig. 9.8
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Microbiology Chapter 9

• RNA polymerase is the enzyme that causes mRNA to
  form
• Translation the process of actually translating
  the genetic information, coded on DNA,
  transferred to mRNA and then expressed by the
  specific synthesis of a particular protein see
  pages 260 - 263
• 1. Codon triplet code on the mRNA
• 2. Anticodon corresponding code on tRNA
• 3. tRNA carries specific amino acid,
  codon-anticodon match insures proper sequence of
  amino acids (see pg. 261 codons code for only
  specific amino acids) transparency

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Microbiology Chapter 9

• Transcription to Translation
• As Polypeptide forms it coils and folds into a
  specific shape

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Figure 9.9
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Figure 9.10
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Figure 9.12
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Figure 9.13
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Figure 9.14
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Figure 9.16Very too Cool
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Figure 9.18

• Differences in eukaryote and prokaryote DNA Exon
  and introns
• Exons Coding regions genetic information,
  transcribed and then translated
• Introns Interspersed between exons, and dont
  code for protein

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Microbiology Chapter 9

• Mutations an inheritable change in an organisms
  genetic information, in its DNA
• Can be simple as one base pair, or complex
  involving many bases
• 2. Can be natural (spontaneous - random
  mistakes), biological (jumping genes
  transposable elements transposons can jump
  around and when inserted they can alter the
  genetic make up of a cell)
• 3. Induced created in the laboratory as result
  of use of chemicals (mutagens) or radiation

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Transformation Naked DNAfig. 924
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Conjugation Sex pilus and plasmidFigure 9.23
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Transduction Phage assisted DNA transfer