Chapter 2: Problem 13
Write down a formula for the population size, \(N_{t}\), as a function of time, \(t\). A strain of bacteria reproduces asexually every 42 minutes. That is, every 42 minutes, each bacterial cell splits into two cells. If, initially, there is 1 bacterium, how long will it take until there are 1024 bacteria?
Short Answer
Step by step solution
Understand the Doubling Concept
Express Population as a Function
Set Up the Equation for Desired Population
Solve for Time \(t\)
Conclusion
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Asexual Reproduction
When an organism reproduces asexually, it creates a clone of itself. This means the offspring are genetically identical to the parent. For example, if we have a strain of bacteria, each bacterium divides and creates two identical daughter cells.
The bacteria population grows exponentially as every single bacterium splits into two. This doubling effect leads to a rapid increase in population size, making asexual reproduction a powerful model for biological growth. Here's why it matters:
- Fast Population Growth: Asexual reproduction allows organisms to quickly grow their numbers, which is crucial for survival and overcoming environmental changes.
- Population Homogeneity: Since offspring are clones, they maintain the same genetic traits, which can be advantageous in stable environments.
- Resource Competition: Rapid growth from asexual reproduction can lead to intense competition for resources, potentially limiting further expansion.
Population Modeling
The bacteria in our exercise follows a specific growth pattern thanks to asexual reproduction. This is modeled using mathematical equations that predict their exponential growth. The formula used is:\[N_{t} = N_{0} \times 2^{t/42}\]
Here's how it all fits together:
- Exponential Growth: The population size doubles after each reproduction cycle, reflecting exponential growth, represented by the base 2 in the formula.
- Time Interval: The exponent \( \frac{t}{42} \) represents the number of 42-minute intervals that have passed, connecting time with the growth cycles.
- Initial Population: Represented by \( N_{0} \), it's the starting quantity of bacteria from which the growth is calculated.
Logarithmic Equations
In the case of our bacterial culture, we want to find when the population reaches 1024. In the equation
\[1 \times 2^{t/42} = 1024\]
we need to solve for \( t \). Defining the growth using logarithms allows us to untangle this exponential equation.
Here's how logarithmic equations help:
- Manageable Solutions: Logarithms convert exponential growth expressions into simpler forms, making it easier to handle complexities.
- Scaling: They provide a way to explore relationships between large numbers, useful for understanding how long processes will take.
- Example: In the given exercise, recognizing that \( 2^{10} = 1024 \) simplifies finding when \( \frac{t}{42} = 10 \), leading to \( t = 420 \) minutes.