BI236 Lecture Notes - Lecture 2: Cell Theory, Paramecium, Plant Cell
BI236 Lecture 2 – Cells & Organelles
Outline
• What is a cell?
• Cell theory
• Types of cells
• Different types of cells
o Bacteria, Archea, Eukaryotes
• Cell organelles
What is a Cell?
• an autonomous biological unit
• smallest living unit
• Individual cells can:
• grow, reproduce, process information, respond to stimuli, communicate,
carry out chemical reactions
• carry hereditary material
• surrounded by a plasma membrane
Cell Theory
• Formally established by Theodor Schleider and Matthias Schwann in 1839, cell
theory (or cell doctrine) is the most basic tenet underlying the field of biology.
Modern cell theory states that…
• The cell is the structural and functional unit of all living things.
• All organisms are composed of one or more cells.
• New cells come from pre-existing cells; lifeforms today have descended in unbroken
continuity from the first primitive cells that arose on earth more than 3.5 billion years
ago.
• Hereditary information passes from parent cell to child cell.
• All cells have the same basic chemical structure.
• The fundamental biochemical reactions of life take place within cells.
Different Types of Cells
• Some cells are visible to the unaided eye
• The smallest objects that the unaided human eye can
• see are about 0.1 mm long.
• Eg. Ameoba proteus, a human egg, and a paramecium
Single cell
organisms→Multi cell organisms→Single cell organisms→Microorganisms
→multi cell organisms→higher degree or organization of cells within the organism→
specialization of cells
Size of Cells
Ameoba proteus
Human Egg
Paramecium
Bacteria
Archea
Yeast - Fungi
Human red blood cells
Plant cells
Human skin cells
All Organisms are Bacteria, Archaea, or Eukaryotes
• Biologists recognized two types of cells
• The simpler type is characteristic of bacteria (prokaryotes) and the more complex
type characteristic of plants, animals, fungi, algae and protozoa (eukaryotes)
• The main distinction between the two cells types is the membrane-bounded nucleus
of eukaryotic cells
A Changing View of Prokaryotes
• Based on rRNA sequence analysis, prokaryotic cells can be
divided into the widely divergent bacteria and archaea
• Biologists now recognize three domains, the archaea, bacteria
and eukaryota
Prokaryotes – Domain Bacteria
• Single cell organisms
• No nucleus, no compartments
• Peptidoglycan cell walls
• Binary fission
• For energy, use organic chemicals, inorganic chemicals, or photosynthesis
Document Summary
Outline: what is a cell, cell theory, different types of cells. Types of cells: bacteria, archea, eukaryotes, cell organelles. What is a cell: an autonomous biological unit, smallest living unit. Individual cells can: grow, reproduce, process information, respond to stimuli, communicate, carry out chemical reactions, carry hereditary material, surrounded by a plasma membrane. Cell theory: formally established by theodor schleider and matthias schwann in 1839, cell theory (or cell doctrine) is the most basic tenet underlying the field of biology. Some cells are visible to the unaided eye. The smallest objects that the unaided human eye can see are about 0. 1 mm long. Ameoba proteus, a human egg, and a paramecium. Multi cell organisms higher degree or organization of cells within the organism specialization of cells. A changing view of prokaryotes: based on rrna sequence analysis, prokaryotic cells can be divided into the widely divergent bacteria and archaea, biologists now recognize three domains, the archaea, bacteria and eukaryota.
