Cell Growth and Reproduction Flashcards

Unit Information: This content pertains to Biology Part 1, Unit 5, Chapter 10.
Primary Focus: The study of cell growth, division, and reproduction.

Fundamental Question: Why are cells small?
The Town Analogy: If a cell is compared to a town, issues arise when the population grows, mirroring the problems a cell faces as it increases in size.
Core Issues of Growth: - Information Overload: As a cell grows, it places too many demands on its DNA. The genetic material cannot provide enough information to support an excessively large cell. - Traffic (Exchange of Materials): The exchange of materials becomes inefficient. The cell struggles to receive necessary nutrients and cannot effectively get rid of wastes.

Surface Area ( $SA$ ): This represents the cell membrane, which dictates how much material can enter or leave the cell.
Volume ( $V$ ): This represents the internal activities and the "stuff" (organelles and cytoplasm) inside the cell.
Ratio Importance: Traffic issues in a cell are directly related to the ratio of surface area to volume.
Mathematical Comparisons of Ratio: - Small Cube: $SA = 6$ , $V = 1$ . The Ratio is $6$ . (Large $SA:V$ ratio). - Medium Cube: $SA = 24$ , $V = 8$ . The Ratio is $3$ . - Large Cube: $SA = 96$ , $V = 64$ . The Ratio is $1.5$ . (Small $SA:V$ ratio).
Diffusion Efficiency: - Large $SA:V$ ratio ( $6$ ): It is easier for materials to diffuse because there is more membrane relative to the internal volume. - Small $SA:V$ ratio ( $1.5$ ): It is harder for materials to diffuse efficiently.

Consequences of Poor Ratio: When the surface-area to volume ratio becomes too small, the rate of chemical exchange decreases significantly, leading to cell death.
Building Larger Organisms: To build larger organisms, nature does not create larger cells. Instead, organisms are built from many small cell subunits.
Volume and Surface Area comparison: - A single large cube ( $30 km$ by $10 km$ side context) may have a surface area of $5400 \mu m^2$ . - A collection of $27$ small cubes occupying the same total volume has a total surface area of $16,200 m^2$ .
Practical Application: The "Potato Lab" by Mr. Dillingsley is used to demonstrate these principles of cell size.

Asexual Reproduction: - Definition: A single parent produces offspring that are genetically identical to the parent. - Speed: It is a fast and quick process. - Mating: There is no need to find a mate. - Offspring Numbers: It allows for the production of many offspring in a short period. - Environmental Adaptability: In stable environments, genetically identical offspring thrive. However, if environmental conditions change, the offspring may not be well adapted to the new conditions.
Sexual Reproduction: - Definition: Involves the fusion of two separate parent cells, producing genetically unique offspring. - Diversity: It increases genetic diversity within a population. - Speed and Growth: It produces relatively fewer offspring, and the growth process takes more time. - Mating: Requires finding a mate. - Environmental Adaptability: In changing environments, genetic diversity can be highly beneficial for survival. However, individual offspring may be less well adapted to the specific current conditions than an identical clone might be.

External Material: Asexual and Sexual Reproduction with the Amoeba Sisters.
Required Tasks: - Finish the Sexual/Asexual Reproduction activities. - Complete Science Journal #2. - Work on assigned Vocabulary. - Complete Edpuzzle #1.