--- title: "Microbial Growth: Generation Time, Growth Curves and Continuous Culture" description: "A population that doubles at a fixed interval grows exponentially, so counts are handled on a log scale and generation time is read from the slope. A closed flask passes through lag, exponential, stat" canonical: https://lightmysky.com/learn/science/microbial-growth-generation-time-growth-curves-and-continuous-culture-mt_ltzgjIBytk source: https://lightmysky.com/learn/science/microbial-growth-generation-time-growth-curves-and-continuous-culture-mt_ltzgjIBytk.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Microbial Growth: Generation Time, Growth Curves and Continuous Culture A population that doubles at a fixed interval grows exponentially, so counts are handled on a log scale and generation time is read from the slope. A closed flask passes through lag, exponential, stationary and death phases, while a chemostat holds a culture in one phase by feeding it steadily. Subject: Science · Area: Microbiology · Ages 18 to 20 Page: https://lightmysky.com/learn/science/microbial-growth-generation-time-growth-curves-and-continuous-culture-mt_ltzgjIBytk ## Ready when they can - Calculates generation time from two counts and the time between them. - Explains why the exponential phase is a straight line only on a log axis. - Says what a chemostat controls that a closed flask cannot. ## Lesson: Counting cells that double Most microbes grow by binary fission: one cell splits into two matching daughters. The time per doubling is the generation time. From two counts, find how many doublings fit between them, then divide the elapsed time by that number. **Example.** A flask holds 100 cells, then 800 six hours later. The counts double three times: 100 to 200 to 400 to 800. Six hours divided by three doublings gives a generation time of two hours. A closed flask moves through four phases: lag while cells adjust, log of rapid doubling, stationary as food runs out, and death as cells die faster than they divide. Each generation multiplies cells by a fixed factor, so the log phase draws straight only on a log axis. **Tip.** A chemostat beats the flask by feeding fresh medium in while washing culture out at the same rate. That holds cells in steady growth without end. Also note the inverse pair: generation time is time per doubling, while growth rate is doublings per time. **Recap.** Find doublings between two counts, read phases off the curve, and hold steady growth with steady feeding. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Archaea: Different Membranes, Extreme Habitats, Separate Domain](https://lightmysky.com/learn/science/archaea-different-membranes-extreme-habitats-separate-domain-mt_isKmuoGgAn) - [Population Growth Curves and Carrying Capacity](https://lightmysky.com/learn/science/population-growth-curves-and-carrying-capacity-mt_KX6rhHF5kj) ## Opens up - [Controlling Growth: What Sterile Means and How It Is Achieved](https://lightmysky.com/learn/science/controlling-growth-what-sterile-means-and-how-it-is-achieved-mt_j1kqpjUMzk) - [Applied Microbiology: Fermentation, Bioremediation and Host Microbiomes](https://lightmysky.com/learn/science/applied-microbiology-fermentation-bioremediation-and-host-microbiomes-mt_WcfGvV_dD9)