Biology Overview of Cells

Overview of Cells

• Cells are the fundamental building blocks of life, essential for independent existence and reproduction.
• Two primary types of cells exist: prokaryotic and eukaryotic, differentiated by the presence of a nucleus.

Prokaryotic Cells

• Unicellular organisms classified under the kingdom Monera, encompassing domains Archaea and Bacteria.
• Size typically ranges from 1 to 10 micrometers, making them significantly smaller than eukaryotic cells.
• Lack a membrane-bound nucleus; genetic material is localized in the nucleoid region.
• DNA is usually a single circular chromosome, facilitating genetic engineering.
• May possess protective features like a capsule or slime layer for defense and adherence.
• Reproduce asexually, primarily through binary fission or budding, allowing for rapid production of identical cells.

Eukaryotic Cells

• More complex and larger cells, ranging from 10 to 100 micrometers, capable of forming multicellular organisms.
• Contain a membrane-bound nucleus housing genetic material organized into multiple linear chromosomes.
• House numerous organelles, including mitochondria, endoplasmic reticulum, and Golgi apparatus, each serving specific cellular functions.
• Reproduce through both mitosis for somatic cells and meiosis for gametic cells (sperm and egg).

Key Differences Between Prokaryotic and Eukaryotic Cells

• Nucleus: Eukaryotic cells possess a defined nucleus, while prokaryotic cells do not.
• Cell Wall Composition:
  • Prokaryotes have cell walls made of peptidoglycan.
  • Eukaryotic plant cells have cellulose, fungal cells have chitin, and animal cells lack a cell wall.
• Genetic Material: Prokaryotic DNA is circular; eukaryotic DNA is linear, organized in pairs.
• Organelles: Eukaryotic cells contain a variety of membrane-bound organelles, unlike prokaryotes, which have few or none.
• Cell Division: Prokaryotes divide by binary fission; eukaryotes use mitosis and meiosis.

Common Features

• Both cell types include:
  • Cytoplasm: The entire content inside the cell membrane, excluding the nucleus.
  • Ribosomes: Non-membrane-bound structures responsible for protein synthesis.
  • Plasma Membrane: A selectively permeable barrier separating the cell’s interior from its external environment.
  • DNA: Contains the genetic instructions crucial for cellular functions.

This quiz explores the fundamental concepts of cells, including their structure and types. You will learn about prokaryotic and eukaryotic cells, their characteristics, and their roles in life. Test your knowledge on the building blocks of life and how they differ from each other.