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Biology Notes on Cells and Their Functions
Learning Objectives
Describe basic structure of animal and plant cells under microscope.
State adaptations of different cells to their functions.
Relate cells and functions to life processes in organisms.
Explain staining in study of cells and tissues.
Cell and its Discovery
Cells are the basic unit of all organisms, with functions of life.
Robert Hooke (1665) observed cells in cork, termed 'cells'.
Contribution by scientists improved understanding of cell structures.
Microscope Inventions
Leeuwenhoek's Microscope: Simple design, magnifying power up to 200x.
Hooke's Compound Microscope: Improved design, magnification up to 2000x.
Electron Microscope: Invented by Ernst Ruska and Max Knoll, magnifies up to 200,000x.
Cell Theory
Proposed by Matthias Schleiden and Theodor Schwann in 1838-39.
Key points:
Basic unit of structure is cell.
Basic unit of function is cell.
All cells arise from pre-existing cells.
Cells contain genes as hereditary material.
Cell Structure
All cells have three parts: cell membrane, cytoplasm, nucleus.
Organelles carry out specific functions:
Cell Membrane: Selectively permeable, regulates substance entry.
Cytoplasm: Site for cellular activities, contains organelles.
Nucleus: Control center of cell, contains genetic material.
Adaptation of Cells
Cells adapt structurally for specialized functions (e.g., sperm cell, root hair cell).
Variability in shapes (e.g., globular, tubular) assists different functions.
Cell Functions & Life Processes
Cellular activity underpins all life activities: movement, reproduction, metabolism, etc.
Staining Techniques
Staining highlights structures for observation under microscopes.
Different stains used for different cell parts to enhance visibility.
Conclusion
Cells are essential for all living organisms and contribute to life processes through their structure and functions.
Understanding cells and their functions is critical in the study of biology and life sciences.