1. Characteristics of the Cell

2. Cells
Cells- the smallest unit that can perform all the functions needed for life
All organisms are made of cells.
Cells all have the same basic parts and processes.
The picture shows onion cells under a microscope.

3. Cell Theory
1665- Cells were first discovered by Robert Hooke when he was looking at cork under a microscope.
“The Wacky History of Cell Theory”
wacky-history-of-cell-theory

4. Current Cell Theory… All organisms are made of one or more cells.
The cell is the basic unit of all living things.
All cells come from existing cells.

5. Cell Structure All cells have the following parts:
Cell Membrane- a layer that covers and protects the cell
Creates a boundary between the inside of the cell and the surrounding environment
Controls what goes in and out of the cell
Cytoplasm- the fluid material inside the cell membrane

6. Cell Structure
DNA- the genetic information that holds information needed to make new cells and new organisms
Organelles- parts inside of the cell that do different jobs Ex: Ribosome, nucleus

7. Prokaryotic and Eukaryotic Cells
Eukaryotic cells have a nucleus and prokaryotic cells do not.
Nucleus- a structure enclosed by a membrane that contains most of the cell’s DNA.
Prokaryotic Cells- do not have a nucleus so the DNA floats in the cytoplasm.
No nucleus
DNA shaped like a twisted rubber band
No membrane-bound organelles
A cell wall outside the cell membrane

8. Prokaryotic and Eukaryotic Cells
have a nucleus
DNA in nucleus
10 times larger than prokaryotic cells
Eukaryotic cells have organelles.
Most eukaryotes are multicellular, but some are unicellular

9. Prokaryotic and Eukaryotic Cells

10. Organization of Living Things
Organism- any living thing
Organisms can be unicellular or multicellular
Benefits of being multicellular
Larger size
Longer life
Specialization

11. Levels of Organization
Cells Tissues Organs Organ Systems Organism

12. Cells are specialized
Multicellular organisms have many different types of specialized cells
Each specialized cell has a particular job called its function.
Cells with special functions generally have a structure that suits them for that job
Ex: The function of a red blood cell is to carry oxygen to other cells. A red blood cell is small and smooth. This helps it slip through small blood vessels.

13. Levels of Organization
Tissue- a group of cells that work together to do a specific job
Ex: muscle cells are organized into muscle tissue
Organ- a structure made of two or more tissues that work together to do a job
Ex: Heart- made of muscle, nerve, and other types of tissues.
Organ system- a group of organs working together to do a job
Ex: the stomach is part of the digestive system
Organism- Organ systems are organized into the organism. The different organ systems work together to carry out all the life functions of the individual.