Plant Cell Anatomy

Plants: The Magical Wizards

  • Plants are amazing because they convert carbon dioxide into oxygen.
  • They only need sunlight and water to survive, unlike animals.
  • Everything we eat either comes from plants or from something that ate plants.

Plant Evolution

  • Plants likely evolved over 500 million years ago.
  • Earliest land-plant fossils date back over 400 million years ago.
  • These were lycophytes, which reproduce through spores.
  • Some lycophytes evolved into scale trees, forming coal forests during the Carboniferous Period.
  • Scale tree forests fossilized into coal.
  • Angiosperms (flowering plants) developed around 65 million years ago.

Cellular Structure: Eukaryotic vs. Prokaryotic Cells

  • Plant and animal cells are eukaryotic, meaning they have a "good kernel" (nucleus).
  • Eukaryotic cells are more advanced than prokaryotic cells.
  • Prokaryotic means "before the kernel" and includes bacteria and archaea.
  • Eukaryotic cells have a nucleus containing DNA and enclosed by a membrane.
  • Eukaryotic cells have organelles suspended in cytoplasm (mostly water).

Differences Between Plant and Animal Cells

  • Plants evolved from green algae.
  • Plant cells have a rigid cell wall made of cellulose and lignin.
  • Cellulose is the most common complex carbohydrate, a chain of glucose molecules.
  • Cellulose is hard to digest for animals.
  • Cell walls provide structure and protection to plants.
  • Lignin and cellulose make trees strong and resistant to deterioration.
  • Lignin and cellulose are roughage for humans; indigestible but useful for the digestive system.
  • Some animals (sloths, goats) have bacteria in their stomachs to digest cellulose into glucose.
  • Humans lack these bacteria and cannot digest cellulose effectively.
  • Cellulose and lignin burn, releasing energy.

Photosynthesis and Plastids

  • Plants make their own food through photosynthesis.
  • Plant cells have plastids, organelles for making and storing compounds.
  • Plastids and mitochondria originated as bacteria absorbed into plant cells.
  • Plastids and mitochondria have double membranes.
  • Chloroplasts are the most important plastids, converting light energy into sugar and oxygen.
  • Green parts of plants contain cells filled with chloroplasts.

Vacuoles

  • Plant cells have a large, central vacuole.
  • Vacuoles store water, providing turgor pressure to reinforce the cell wall which results in rigidity.
  • Vacuoles also store other compounds and wastes.
  • Animal cells have vacuoles, but they are smaller and don't provide structural support.

Basic Plant Cell Anatomy

  1. Cell Wall: Rigid, made of cellulose and lignin. Provides structure. Cell wall <br/>≠<br />\neq cell membrane. It's on the outside of the cell membrane. Cell wall <br/>≠<br />\neq bone. Plant bone doesn't exist.
  2. Nucleus: Contains genetic information and directs cell activities; found in a membrane bag.
  3. Plastids: Including chloroplasts, which are food-making machines that use photosynthesis.
  4. Central Vacuole: Stores water and other substances, providing structural support.

Impact and Appreciation

  • Plant cells stacked together form a plant.
  • Unique features of plant cells enable plants to provide food and air.
  • Appreciate plants for their hard work and service.