Introduction to Cells

Introduction to Cells

• Cells are the fundamental units of life.
• All living organisms are composed of cells, or in some cases, a single cell.
• Cells carry out all the processes necessary for life, including metabolism, growth, and reproduction.
• Two basic cell types exist: prokaryotic and eukaryotic.

Prokaryotic Cells

• Prokaryotic cells are generally smaller and simpler than eukaryotic cells.
• They lack a nucleus and other membrane-bound organelles.
• They contain a single chromosome located in a region called the nucleoid.
• Examples include bacteria and archaea.
• Key features include:
  • Cell wall: Provides structural support and protection.
  • Plasma membrane: Controls substance passage into and out of the cell.
  • Cytoplasm: Contains the cell's internal fluid and other components.
  • Ribosomes: Synthesize proteins.
  • Flagella or pili: Enable movement or attachment.

Eukaryotic Cells

• Eukaryotic cells are larger and more complex than prokaryotic cells.
• They possess a nucleus and other membrane-bound organelles.
• The nucleus houses the cell's genetic material.
• Examples include animal cells, plant cells, fungi, and protists.
• Key features include:
  • Nucleus: Contains the cell's DNA.
  • Endoplasmic reticulum (ER): Involved in protein synthesis and lipid metabolism.
  • Golgi apparatus: Processes and packages proteins.
  • Mitochondria: Generate energy (ATP) through cellular respiration.
  • Vacuoles: Store water and other substances.
  • Lysosomes: Contain enzymes for digestion.
  • Cytoskeleton: Provides structural support and facilitates movement.
  • Flagella or cilia: Enable cell movement or substance transport.

Cell Structures

• Cell membrane (plasma membrane): A thin barrier enclosing the cell, regulating substance passage.
• Cytoplasm: The jelly-like substance inside the cell, containing organelles.
• Organelles: Specialized structures within the cell performing specific functions.
• Ribosomes: Organelles responsible for protein synthesis.
• Mitochondria: Organelles producing energy through cellular respiration.
• Nucleus: The cell's control center, housing its DNA.
• Endoplasmic reticulum (ER): A network of membranes involved in protein and lipid synthesis.
• Golgi apparatus: Modifies, sorts, and packages proteins.
• Vacuoles: Membrane-bound sacs storing water, nutrients, or waste.
• Lysosomes: Contain enzymes for breaking down cellular waste.

Plant Cell vs Animal Cell

• Plant cells have structures lacking in animal cells, such as chloroplasts and cell walls.
• Chloroplasts: Conduct photosynthesis, converting light energy to chemical energy.
• Cell wall: Rigid, cellulose-based structure providing support and protection.
• Animal cells contain centrioles, absent in plant cells.
• Centrioles: Play a role in cell division.

Cell Size and Shape

• Cells vary significantly in size and shape, dictated by their function.
• Cell size is constrained by the surface area-to-volume ratio.
• Cell shape often reflects its specific function.

Cell Division

• Cell division creates two or more daughter cells from one parent cell.
• Crucial for growth, repair, and reproduction.
• Mechanisms include mitosis (eukaryotic) and binary fission (prokaryotic).

Importance of Cells

• Cells are fundamental units of life.
• Their functions dictate the overall functioning of the organism.
• Maintaining healthy cells is essential to human health.

This quiz explores the fundamental concepts of cells, the basic units of life. It covers the differences between prokaryotic and eukaryotic cells, their structures, and functions essential for living organisms. Test your understanding of cellular biology and its significance in life sciences.