Overview of Cells: Animal Cell Characteristics

Overview of Cells

• Cells are the fundamental structural and functional units of organisms, derived from the Latin word "cella," meaning "small room."
• Cell classification can vary; major types include eukaryotic (with nuclear membrane) and prokaryotic (without a well-defined nucleus).
• Organisms can be unicellular (single-celled), multicellular (many cells), or acellular (lacking cells).

Animal Cell Characteristics

• Animal cells are eukaryotic, featuring a defined nucleus and membrane-bound organelles like mitochondria, endoplasmic reticulum, and Golgi apparatus.
• Surrounded by a plasma membrane, which separates internal organelles from the external environment.
• Cytoplasm, a fluid medium, suspends cellular components.
• Animals are multicellular, with specialized cells performing diverse functions, allowing for adaptation to active lifestyles.

Types of Animal Cells

• Numerous types exist, each tailored for specific functions.
• Lack chloroplasts, distinguishing them from plant cells as they do not perform photosynthesis.

Plant Cell Characteristics

• Plant cells are eukaryotic, having a true nucleus and similar organelles to animal cells, but also possess chloroplasts for photosynthesis.
• Enclosed by a rigid cell wall, providing structure and support.

Plant Cell Functions

• Primary role in building plant tissues.
• Photosynthesis occurs in chloroplasts, using sunlight, carbon dioxide, and water.

Types of Plant Cells

• Collenchyma Cells: Flexible and support growth without lack of hardening agents in primary walls.
• Sclerenchyma Cells: Harder, providing structural support due to the presence of lignin.
• Parenchyma Cells: Living cells involved in gas exchange, food production, storage, and metabolism; typically flexible due to thinner walls.
• Xylem Cells: Specialized for transporting water and minerals from roots to leaves.
• Phloem Cells: Transport cells responsible for distributing food produced in leaves to various plant parts.

Bacterial Cell Characteristics

• Bacterial cells are prokaryotic, lacking a well-defined nucleus and membrane-bound organelles.
• Genetic material is found in an irregular-shaped region within the cell, in contrast to defined organelles in eukaryotic cells.

Functions of Bacterial Cells

• Cytoplasm (protoplasm) facilitates cell growth, metabolism, and replication.
• Composed of water, enzymes, nutrients, waste, gases, and contains structures like ribosomes, chromosomes, and plasmids.

Types of Bacterial Cells

• Classified into five basic shapes.
• Can exist as single cells, pairs, chains, or clusters.

Differences Among Cell Types

• Key distinctions among plant, animal, and bacterial cells based on structure, organelles, and functions.