Module 3 Friday p1: Introduction to the Cell

Cell Overview

• Cells are the basic unit of structure and function in organisms.

• Most cells are microscopic and require a microscope for visualization.

  • Light microscopes are commonly used.

  • Electron microscopes are needed for detailed views and smaller cells.

• Analogy: Comparing a cell to a city helps understand its functions.

  • Organelles are like businesses performing work for the cell.

• Plasma membrane interacts with the environment and controls entry/exit of substances.

Types of Cells

• Two main categories:

  • Prokaryotic

    • Domains: Bacteria and Archaea

      • These are single-celled organisms

    • Bacteria are found everywhere (skin, gut, soil, etc.)

    • Archaea thrive in extreme environments like deep sea vents.

  • Eukaryotic

    • Make up organisms like humans, plants, and fungi.

    • More complex than prokaryotic cells.

Basic Cellular Features for all cells

• Plasma membrane (cell membrane):

  • Barrier controlling what enters and exits the cell.

• Cytosol:

  • Runny, gelatin-like mixture in the cell.

• Cytoplasm:

  • Refers to the space within the cell.

  • Cytosol is the fluid within that space.

• Genetic Information:

  • DNA in the form of genes.

  • Genes instruct the cell to produce proteins.

• Ribosomes:

  • Responsible for protein synthesis.

Prokaryotic Cells

• Basic cell type, including bacteria.

• Lack a nucleus.

  • DNA resides in a region, not a membrane-bound nucleus.

• Lack membrane-bound organelles.

• Contain cytoplasm where cellular components float.

• Contain ribosomes for protein synthesis.

• Plasma membrane present.

• Most also contain a cell wall.

• Some have flagella for movement and fimbriae for attachment.

  • 

Eukaryotic Cells

• More complex than prokaryotic cells.

• DNA is contained within a nucleus.

  • The nucleus has a membrane around it.

• Contain organelles with membranes.

• Cytoplasm is the region between the plasma membrane and the nucleus.

• Eukaryotic cells are usually larger than prokaryotic cells.

• Plasma membrane is a selectively permeable barrier.

Cell Size Limits

• Cells are small due to surface area to volume ratio.

• Surface Area:

  • The amount of area on the outside of the cell

• Volume:

  • The space inside the cell $Surface Area / Volume$

• A large cell would have a volume too big for its surface area to manage.

• Multiple smaller cells increase the surface area for diffusion.

• Diffusion is more efficient in smaller cells.

Eukaryotic Cells - Compartmentalization

• Eukaryotic cells contain membrane-bound organelles.

• Organelles compartmentalize functions.

• Both plant and animal cells have similar organelles.

• Biological membranes surround organelles and the plasma membrane.