Cell Theory, Prokaryotes, and Eukaryotes

• Cell theory consists of three parts.
• All living organisms consist of cells.
• A cell is the fundamental unit of structure and function in living organisms.
• All cells originate from pre-existing ones.
• MRS GREN stands for fundamental life processes including:
• Movement
• Respiration
• Sensitivity
• Growth
• Reproduction
• Excretion
• Nutrition

Prokaryotes

• Prokaryotes also called bacteria are unicellular organisms.
• Prokaryotes possess a simple structure
• Prokaryotes lack a nucleus.
• Prokaryotes represent the oldest type of cell.
• Prokaryotes do not have membrane-bound organelles.
• Prokaryotes have DNA in the form of a singular chromosome.
• Prokaryotes have a higher surface area.

Eukaryotes

• Eukaryotes have a membrane-bound nucleus.
• Eukaryotes are internally complex.
• Eukaryotes contain a nucleus and organelles.
• Eukaryotes evolved from prokaryotes.
• Eukaryotes can be single-celled or multicellular.
• Eukaryotes are like a large house consisting of separate rooms (organelles) and organized compartments with a complex internal structure.

Similarities

• Both prokaryotes and eukaryotes have:
• DNA
• Ribosomes
• Cytoplasm
• Plasma Membrane

Cell Size

• Cells need to transport materials in and out
• Required materials: Nutrients, etc
• Waste materials: Waste
• Cells must have sufficient surface area to facilitate the exchange of materials.
• As cell volume increases, the amount of transporting needed for the cell increases.
• As object size increases, surface area to volume ratio decreases

Energy

• Living cells require energy for:
• movement
• synthesis
• maintenance or a stable intracellular environment, known as homeostasis
• Energy is continually transformed from one type to another in living cells.
• The 'Law Of Conservation of Energy' states that energy cannot be created or destroyed, but simply changed from one form to another.
• Energy can exist in various forms, including:
• Light
• Heat
• Chemical
• Kinetic energy
• Living cells convert chemical energy into more useful forms.

Autotrophs and Heterotrophs

• Autotrophs make their own food using solar or chemical energy.
• Examples include plants, algae, and some bacteria.
• Heterotrophs cannot make their own food and must consume other organisms for energy.
• Examples include animals, fungi, and most bacteria.
• Autotrophs produce energy, while heterotrophs rely on consuming others.
• Autotrophs are essential as they form the base of the food chain providing support for heterotrophs.

Photosynthesis and Fermentation

• Photosynthesis is the process by which plants produce their food.
• They take in sunlight, carbon dioxide (CO2), and water (H2O) and convert them into glucose (sugar) and oxygen (O2).
• Fermentation is the process of breaking down substances into simpler ones.
• Fermentation, or ATP production without oxygen (anaerobically), begins with glycolysis in cytoplasm giving rise to pyruvate.
• Pyruvate produced in fermentation is converted into waste products where it produces a small amount of ATP.

Cell Requirements

• Autotroph
• Heterotroph
• Phototroph

Metabolic Waste

• Examples: carbon dioxide and nitrogen
• Humans consider CO2 as a metabolic waste product and it must be removed to breathe.
• Animals need CO2 for photosynthesis for food.