Final

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Final

• Roughly,
• 1/3 Bacterial Genetics,
• 1/3 Mendel,
• 1/3 Replication, Transcription, Translation,
• 99 new, 1 cumulative.

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Conjugation

• ...temporary fusion of two single-celled
  organisms for the transfer of genetic material,
• in bacteria, the transfer of genetic material is
  unidirectional
• F F- F Hfr.

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F Pilus
a filament-like projection from the surface of a
bacterium.
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High Frequency of Recombination(Hfr)

• ...bacteria exhibiting a high frequency of
  recombination,
• an alteration DNA sequence such that the genotype
  of subsequent individuals differs from the
  parent,
• specifically, strains with a chromosome
  integrated F factor that is able to mobilize and
  transfer part of the chromosome to the F- cell.

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Bacterial Nomenclature

• genes not specifically referred to are considered
  wild-type,
• Strain A met- bio-
• x
• Strain B thr- leu- thi-

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FCells

• an F factor from an Hfr cell excises out of the
  bacterial genome and returns to plasmid form,
• often carries one or more bacterial genes along,
• Fcells behave like an F cells,
• merizygote partially diploid for genes copied on
  the Fplasmid,
• Fplasmids can be easily constructed using
  molecular biology techniques.

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F factor Review
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Transformation

• ...heritable exchange brought about by the
  incorporation of exogenous DNA.

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Donor and Recipient
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Exogenous DNA Incorporated
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T4 Bacteriophage

• infects E. coli,

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Two Bacteriophage Strategies

• Lytic,
• a type of viral life cycle resulting in the
  release of new phages by death and lysis of the
  host cell,
• Lysogenic,
• a type of viral life cycle in which the visus
  becomes incorporated into the host cells
  chromosome.

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Lytic vs Lysogenic
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Generalized Transduction

• enzymatic process which can result in the
  transfer of any bacterial gene between related
  strains of bacteria.

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Specialized Transduction

• upon excision of the prophage, adjacent host DNA
  is taken along,
• the completion of the lytic cycle and subsequent
  infection of another host moves the flanking DNA
  to another bacteria.

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T Plasmids

• bacteria also have plasmids that they transfer
  to other organisms,
• upon infection, the T plasmid enters the host
  cell, becomes incorporated in the host genome,
  and the T plasmid genes become expressed,
• Agrobacterium tumefaceins transfers genes that
  force plants to make strange sugars, that only
  the Agrobacterium can digest.

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Transposable Elements

• a segment of DNA that can move to, or move a
  copy of itself to another locus on the same or a
  different chromosome (hopping DNA),
• may be a single insertion sequence, or a more
  complex structure (transposon) consisting of two
  insertion sequences and one or more intervening
  genes.

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Mutation in Bacteria

• the ultimate source of variation in bacteria is
  spontaneous mutation,
• generally errors in DNA replication,
• mutations occur in specific genes at a rate of 1
  in 106 to 1 in 107 cells,
• adaptive mutations are quickly replicated and
  adaptive colonies predominate.

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Bacteria are Geniuses

• Cloning identical copies,
• Gene therapy insertion of a healthy, or
  functional gene into a organism lacking a good
  gene,
• Defense develop genes to ward off poisons,
  predators, etc.
• Genetic engineering inserting DNA into another
  organism to do your bidding,
• Harness Mutation to speed evolution.

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Eukaryotic Genetics

• Mendelian Genetics,
• applied meiosis.

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Meiosis is the basis for extensive variation
among members of a population.
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Monohybrid crosses

• Matings between individuals that differ in only
  one trait,
• yellow pea x green pea,
• violet flower x white flower
• tall x dwarf
• round seed x wrinkled seed
• full pod x constricted pod
• etc.

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Monohybrid Cross
Generation Parental (P) First Filial
(F1) Second Filial (F2)
yellow pea green pea (pollen)
(eggs)
x
grow plants,cross pollinate
allow to self-fertilize
all yellow
6022 yellow 2001 green 3 1
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Mendels First Three Postulates

• Unit Factors in Pairs
• Dominance/Recessiveness
• Segregation

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Postulates 1-3 AppliedF1 Generation

• P1 Yellow Green Phenotype
• YY yy Genotype
• Gametes Y y
• Yellow Phenotype
• F1 Yy Genotype

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Postulates 1-3 AppliedF2 Generation

• Yellow Phenotype
• F1 Yy Genotype
• F1 Self-Cross Yy Yy
• F2

Yy
Yy
yy
YY
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Test Cross

• a cross of a dominant phenotype individual with
  a recessive homozygous individual,
• by mating an individual with a dominant
  phenotype and an unknown genotype with a true
  breeding homozygous recessive individual, the
  phenotype of the offspring represent the genotype
  of the unknown parent.

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Mendels Forth PostulateLaw of Independent
Assortment

• Alleles of different genes assort independently
  of one another during gamete formation.

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Dihybrid Crosses

• Monohybrid Cross,
• one set of contrasting traits,
• Y versus y.
• S (smooth) versus s (wrinkled).
• Dihybrid Cross,
• YYSS x yyss,

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• S_ Y_
• S_yy
• ss Y_
• ssyy

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3
3
1
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Independent Assortment

• Y_ 12
• yy 4

• S_ 12
• ss 4

Still 31 ratios!
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Replication

• DNA synthesis.

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General Gene Structure
Terminator
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3
Promoter Region
Structural Region
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Initiation Complex

• ...Transcription Factors
• proteins,
• from expressed genes,
• themselves under transcriptional control.

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Transcription

• ...the synthesis of mRNA from a DNA template.

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Elongation

• Nucleotides are added to the 3 end of the
  elongating RNA.

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Post Transcriptional Modification I

• Occurs in the nucleus.
• Increases stability, may help transport and
  sorting.

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Post Transcriptional Modification II

• Introns affect expression.
• Differential splicing can alter the final
  proteins function.
• Provides functional cassettes, for evolutionary
  mixing and matching.

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Genetic Code

• RNA is an intermediary in the transfer of
  information from DNA to the synthesis of protein,
• how is that information organized?

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Translation

• Protein synthesis.

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tRNA
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Study Fig. 17.13
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Elongation (3 steps)
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Termination