Topic 1 Notes Tallas Filled In

Cell Theory

Three Main Points:

  • All living things are composed of cells.

  • Cells are the fundamental unit of life, carrying out all life functions.

  • All cells arise from other cells.

Cell Theory & the Experimental Method

In 1745, Louis Pasteur's experiment aimed to demonstrate that cells could only arise from other living things (theory of biogenesis).

Pasteur's Experimental Process:

  • Boiled nutrient broth in two different containers:

    • Open Flask: Allowed air exposure, leading to microbial growth.

    • 'S' Curved Flask: Prevented microbes from entering, showing no growth.

  • Conclusion: Microbial growth in the open flask was due to microbes from air, not spontaneous generation.

Pasteur's Experiment: Variables

  • Manipulated Variable: Type of flask (open vs. 'S' curve)

  • Controlled Variables:

    • Type of broth used

    • Duration of the experiment

    • Boiling process

  • Responding Variable: Presence of microbial growth

Levels of Cellular Organization: Components & Definitions

  • Organelles: Mitochondria (basic units of life - e.g., blood cells).

  • Cells: Grouped to form tissues (e.g., muscle tissue).

  • Tissues: Work together to form organs (e.g., heart).

  • Organs: Perform specific functions as part of organ systems (e.g., circulatory system).

Early Microscopes & Microscopists

Scientists made significant contributions to microscopy:

  • Hans & Zacharias Janssen: Developed the first compound microscope.

  • Robert Hooke: Observed cells and introduced the term "cell".

  • Antoni van Leeuwenhoek: Improved microscope design, identified single-celled organisms.

Modern Compound Light Microscope: Key Components and Functions

  • Eyepiece (M): Lens for viewing.

  • Body (L): Supports eyepiece.

  • Arm (K): Supports microscope.

  • Revolving Nosepiece (A): Allows switching of objective lenses.

  • Objective Lenses (B): Different levels of magnification.

  • Stage Clips (C): Hold slide in place.

  • Stage (D): Surface for slide.

  • Diaphragm (E): Controls light intensity.

  • Light Source (F): Illuminates specimen.

  • Base (G): Provides stability.

  • Power Switch (H): Turns microscope on/off.

  • Fine Adjustment (I): Sharpens image (used in medium/high power).

  • Course Adjustment (J): Moves stage up/down (used primarily in low power).

Using a Microscope

Determine Magnification:

  • Formula: Eyepiece Magnification x Objective Lens Magnification.

Determine Specimen Size:

  • Convert field diameter from mm to um:

    • Formula: Field Diameter (um) = Field Diameter (mm) x 1000.

  • Field Diameter Calculation:

    • Use the formula: M1F1 = M2F2, where M1 and M2 are the magnifications of the first and second observations, and F1 and F2 are the field diameters corresponding to those magnifications. This helps in correlating the actual size of the specimen under different magnifications.

Guidelines for Scientific Drawings

  • Include title, magnification, field diameter, scale, and a labeled legend.

Practice Questions (Review)

  • Sizing Epithelial Cells: Given a diagram and field view information, calculate actual cell size and scale of drawing.

  • True/False Statements: Identify inaccuracies and correct them based on cell theory and microscopy.

  • Reasons for Viruses Not Being Alive: Explain the dependency of viruses on hosts for reproduction.

  • Diagram Scale Calculation: Given the measurement of a structure and its actual width, calculate the scale of the diagram.

  • Color Coding Activity on Microscope Components: Activity involving coloring and labeling microscope parts to aid in memorizing functionalities.