20min - Traktorkestar · 20min Author: Balthasar Streit Created Date: 2/2/2014 3:46:16 PM ...
Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal...
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Transcript of Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal...
![Page 1: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/1.jpg)
Binary fission of bacteria
![Page 2: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/2.jpg)
• E.coli genome size: 4.6 x 106 nucleotides
• Generation time at optimal conditions: 20min
• DNA replication rate: 1000nt/s ≈ 1.2 x 106
nt/20min
• About 25% of genome can be replicated in one generation time
![Page 3: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/3.jpg)
Population growth• Growth rate: change of cell number per unit time• When growth is unlimited, growth rate is low at
first, increases logarithmically• Plotted on semi-log paper, growth is a straight line• Generation time: time required for one cell to grow
into two cells (varies from several minutes to months)
• Specific growth: instantaneous change in relative cell numbers (µ)
• µ = ln(2)/generation time
![Page 4: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/4.jpg)
Logarithmic growth
![Page 5: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/5.jpg)
Batch growth stages
![Page 6: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/6.jpg)
Lag and Exponential
• Lag phase– Longer when inoculum conditions differed– Some inocula may require synthesis– Apparent lag caused by partial death of inoculum
• Exponential phase– Logarithm of cell numbers increases linearly– Specific growth rate is constant—characteristic of
growth conditions– Cell physiology is constant—best source for
biochemical studies is late exponential phase
![Page 7: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/7.jpg)
Stationary and Death
• Stationary phase– Culture is eventually limited by substrate or nutrient
exhaustion or product accumulation
– Metabolism changes to accommodate the limitation
– Lysis of some cells may lead to growth in others
– Cell increase equals decrease (cryptic growth)
• Death phase– Death is generally logarithmic, but slower than growth
– Sometimes death rate changes after hours or days
![Page 8: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/8.jpg)
Calculating specific growth rate
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Counting Chamber
![Page 10: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/10.jpg)
Counting cells in a chamber
![Page 11: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/11.jpg)
Quantitative plating
![Page 12: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/12.jpg)
Pour plates
![Page 13: Binary fission of bacteria. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2.](https://reader036.fdocuments.net/reader036/viewer/2022062517/56649f1e5503460f94c3587e/html5/thumbnails/13.jpg)
Pour-plating techniques
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Optical density