Biology Chapter Cell Theory

Definition and Discovery of Cells

• Cells are the smallest unit of life.
• Robert Hooke first discovered dead cells.
• Anton von Leeuwenhoek was the pioneer in discovering living cells.

Contributions to Cell Theory

• Mathias Schleiden observed that all plants are made of cells.
• Theodor Schwann noted that all animals consist of cells.
• Rudolph Virchow concluded that cells arise from existing cells.
• Three fundamental components of the cell theory:
  • All living things are composed of cells.
  • The cell is the fundamental unit of life.
  • Cells originate from other living cells.

Prokaryotic vs Eukaryotic Cells

• Prokaryotic cells predate eukaryotic cells.
• Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells possess these features.
• Similarities between both types include cell membranes, chromosomes/DNA, ribosomes, and cytoskeleton.

Examples of Cells

• Prokaryotic example: Bacterial cell.
• Eukaryotic examples: Plant cell and animal cell.

Plant and Animal Cell Comparisons

• Both contain membranes, nuclei, chromosomes, ribosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, and cytoskeleton.
• Differences:
  • Plant cells have cell walls, vacuoles, and chloroplasts; animal cells do not.
  • Animal cells possess flagella, lysosomes, and centrioles; plant cells do not.
  • Plant cells are typically square; animal cells are round.

Cell Functionality

• Cells compared to factories for their collaborative functioning.
• ATP is the energy used by cells.
• Mitochondria produce ATP and are termed the powerhouse of the cell.

Energy Production in Cells

• Animal cells obtain energy through consuming food, while plant cells convert sunlight into energy via chloroplasts through photosynthesis.

Nucleus and Ribosomes

• The nucleus serves as the control center, housing the instructions for product creation.
• The nucleolus produces ribosomes.
• Chromatin or DNA in the nucleus contains the genetic instructions for protein synthesis.

Protein Production Process

• Ribosomes are responsible for assembling proteins.
• Ribosomes can be found on the Rough Endoplasmic Reticulum (Rough ER).
• After assembly on the Rough ER, proteins are sent to the Golgi apparatus for inspection, sorting, and shipping.
• The Golgi apparatus can send proteins out of the cell through Golgi vesicles or route them to lysosomes for degradation.

Cell Storage and Waste Management

• Vacuoles act as storage for cellular materials; they are larger in plant cells and play a role in homeostasis and storing water.
• Lysosomes function as the cell's waste disposal system.

Cell Membrane and Barriers

• The cell membrane regulates the entry and exit of substances, creating a protective barrier.
• Plant cells have an additional protective layer called the cell wall, providing extra support.

Cell Movement Structures

• Flagella are long tails used for movement, while cilia are small hair-like structures that also assist in movement.
• Cytoplasm serves to cushion and support the organelles within a cell.