DNA

1
DNA
2
DNA
3
Chromosomes, Eukarotic
4
Chromosomes, Bacterial
Note Closed, Circular, Singular, and Haploid
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Gene
E. coli 5 million bp Phage T4 170,000 bp
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Gene
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Alleles
Big Difference between many Eucaryotes and most
Bacteria Bacteria, as Haploids, Express all of
their Alleles
Alleles simply are different Nucleotide Sequences
found at the same Location on Different
Chromosomes
Usually the differences are quite subtle, e.g.,
one or two nucleotides different
8
Mutations
New Alleles arise via Mutation The new Allelles
may or may not be Functionally Different
9
Mutations
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Auxotroph Prototroph
Prototrophic microbes that live on a minimal
growth medium inorganic salts energy
source. Auxotrophic mutant microbes must be
supplied with certain additional nutrients to
grow.
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Auxotroph Prototroph
Neurospora crassa Wt are ad leu Auxotrophs
are ad leu
ad
leu
ad/leu
Control
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Selecting for Auxotrophs

• Plate the auxotrophs on plates with various
  supplements to test for phenotypes

Wash cells, remove penicillin and grow auxotrophs!
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Filtration Selection for Auxotrophs
14
Selection for Prototroph Revertants
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Transcription
Certain viruses have genes consisting of
single-stranded RNA These viruses can be either
plus-stranded or minus-stranded Plus-stranded
RNA can serve as mRNA Minus-stranded RNA serve
as templates for the synthesis of mRNA
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Transcription
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Link to Next Presentation
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Acknowledgements
www.uta.edu/biology/mcallister/
5312/download/14_Mutation.ppt homepage.smc.edu/bob
er_mary/Bio2022/ gene20mut20web1.ppt