Biology
Unit 1 Notes:
Types of Cells
(1) Types of Organisms
• Unicellular Organisms:
• Organisms that are made of only one single cell.
• The single cell completes all characteristics of life and maintains homeostasis on its
own.
• Multicellular Organisms:
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Organisms made of many different types of specialized cells.
Each different body part / organ is made of different types of cells.
Each type of cell has a unique structure and function.
All of the different cells must work together to complete the characteristics of life, and
homeostasis.
(2) Multicellular Organization
• Smallest Level (Microscopic)
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Atoms & Molecules
Cells (The basic units of life.)
Tissues (Similar cells working together on a common function.)
Organs (Different types of tissues working together on a common function.)
Organ Systems (Different types of organs working together on a common function.)
Organism (All organ systems working together to maintain homeostasis.)
• Largest Level (Macroscopic)
(3) What is a cell?
• The cell is the most basic unit of living things.
• The Cell Theory States that:
• All living things must be made of at least one cell.
• The cell is the basic unit of life.
• New cells must come from old cells (pre-existing cells).
The Weird Theory of the Cell Theory
• https://youtu.be/4OpBylwH9DU
(4) Types of Cells
• Prokaryotic Cells:
• Cells without a nucleus.
• Example = Bacteria
• Eukaryotic Cells
• Cells with a nucleus.
• Example = Plant + Animal Cells
Prokaryotic Cell
Eukaryotic Cell
Comparing Prokaryotic and Eukaryotic
Cells
• All cells have several basic features.
• They are bounded by a plasma membrane.
• They contain a semifluid substance called the
cytosol.
• They contain chromosomes.
• They all have ribosomes.
Prokaryotic Cells
• Do not contain a nucleus
• Are smaller than eukaryotic cells.
• Lack internal structures
surrounded by membranes.
Eukaryotic cells
• Contain a true
nucleus, bounded
by a membranous
nuclear envelope
• Are generally quite
a bit bigger than
prokaryotic cells
Eukaryotic vs. Prokaryotic
Eukaryotic Cell
Prokaryotic Cell
Nucleus
Present
None
Cell Wall
Only plant and fungi
Present
Cell Types
uni- and multicellular
Unicellular
Organelles
Present
Absent
Chromosomes
More than one; Linear
One; Circular
Cytoskeleton
present
absent
Examples
Animals, Plants, Fungi
Bacteria, Archea
The Three Domains of Life
• At the highest level,
life is classified into
three domains
• Bacteria
• Archaea
• Eukaryota
The Three Domains of Life
• Domain Bacteria and domain Archaea
• Prokaryotes
• Domain Eukarya
• Eukaryotes
• Includes the protists and the kingdoms
Plantae, Fungi, and Animalia