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:• 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)• 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