Cell Types

Introduction and Definitions

• Cell Theory: Cells serve as the foundational units of life.
  • All living organisms are composed of cells.
  • Cells play an essential role in organismal growth and repair.
  • The structure and function of cells elucidate biological processes.

Historical Development

Key Figures and Impact

• Robert Hooke: First identified "cells" in cork (1665), recognising cellular structures in living entities.
• Anton van Leeuwenhoek: Discovered living cells, validating their presence in life forms.

Expanded Timeline

• 1838-1839: Schleiden & Schwann posited that cells constitute the basic unit of structure and function in plants and animals.
• 1855: Rudolf Virchow introduced the idea that all cells originate from pre-existing cells, rounding out classical cell theory.

These developments established a framework for modern concepts such as cellular metabolism and genetics.

Societal Influence

• Technological Advancement: Enhanced microscopy significantly influenced the development of cell theory.
• Industrial Revolution: Provided scientific resources, enabling new discoveries.

Evolution of Scientific Methods

Technological Advancements

• Advancements in microscopy facilitated the identification of cellular organelles like chloroplasts, which are essential for photosynthesis.

Reflection on Historical Context

• Social Factors: Increased societal interest and industrial progression propelled cell biology forward.
• Philosophical Shifts: Advocated for systematic inquiry and technological innovation.

Historical Experiments and Modern Insights

• Hooke's Cork Examination: Proposed the concept of cellular structure, pivotal for biological understanding.
• Van Leeuwenhoek's Observations: Underlined life's complexity at a microscopic level, leading to modern microbiology.

These experiments contribute to fields like genetic engineering and disease research today.

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Types of Cells: Prokaryotic and Eukaryotic

Prokaryotic Cells

Basic Characteristics

• Absence of Nucleus: Genetic material resides in the nucleoid.
• Limited Compartmentalisation: Primarily consists of ribosomes.
• Size: Smaller, supporting rapid growth and environmental adaptability.

Examples

• E. coli: Assists digestion in the intestines.
• Thermococcus: Survives in extreme environments.

Structural Components

Key Structures

• Cell Wall: Provides structural protection and maintains cell shape.
• Nucleoid: Contains primary genetic material.
• Plasmids: Circular DNA, integral for antibiotic resistance.
• Ribosomes: Sites of protein synthesis.

Biological Roles

• Nitrogen Fixation: Transforms atmospheric nitrogen into usable forms for plant nutrition.
• Chemosynthesis: Generates energy through chemical reactions in the absence of sunlight.
• Adaptation: Thrive in extreme conditions, illustrating resilience.

Biochemical Composition

• Proteins: Facilitate cellular functions.
• Lipids: Fundamental for cell membrane formation.
• Carbohydrates: Offer energy reserves.

Eukaryotic Cells

• Eukaryotic Cells Definition: Eukaryotic cells exhibit complexity, characterised by a nucleus and membrane-bound organelles.

Key Structures and Their Functions

• Nucleus:
  • Encased with genetic material, regulates cell operations.
• Mitochondria: Known as the powerhouse, they generate ATP and are abundant in energy-intensive cells such as muscle cells.

Comparison Table

Feature	Prokaryotic Cells	Eukaryotic Cells
Nucleus	Absent	Present
Size	Smaller	Larger
Organelles	Limited (mainly ribosomes)	Numerous, membrane-bound

Key Organelles of Eukaryotic Cells

• Endoplasmic Reticulum (ER):

  • Rough: Engages in protein synthesis.
  • Smooth: Involved in lipid synthesis and detoxification.

• Golgi Apparatus: Modifies, sorts, and packages proteins.

• Chloroplasts (present in plant cells): Sites of photosynthesis.

Ecological Roles

• Plants: Chloroplasts harness solar energy, influencing ecosystems and the carbon cycle.
• Animal Functions: Mitochondria support cellular respiration.

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Introduction to Microscopy Technologies

• Importance: Microscopy is crucial for progressing in cell biology.

Detailed Types of Microscopy

• Light Microscopy: Utilises visible light, commonly employed in laboratories.

• Electron Microscopy:

  • TEM: Provides high-resolution images revealing fine cellular details.
  • SEM: Delivers 3D images of surfaces.

• Fluorescence Microscopy: Illuminates dynamic cellular processes.

Advanced Imaging Technologies

• Confocal Laser Scanning Microscopy: Generates 3D imaging.

• Super-resolution Microscopy: Achieves superior detail.

Challenges in Microscopy

• Artefacts: Misleading structures resulting from sample errors.
  • Strategies: Employ meticulous sample preparation and precise calibration.

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Conclusion

Understanding the types of cells—prokaryotic and eukaryotic—is fundamental to biology:

• Prokaryotic cells: Simple, quickly reproduce, adaptable across diverse environments.
• Eukaryotic cells: Complex, energy-efficient, support critical biological functions.

These insights underscore their vital ecological roles and evolutionary significance.