Cell Theory Early studies led to the development

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Cell Theory • Early studies led to the development of the cell theory. –

Cell Theory • Early studies led to the development of the cell theory. – The Cell theory has three principles. 1. 2. 3. All organisms are made of cells. All existing cells are produced by other living cells. The cell is the most basic unit of life.

All cells share certain characteristics. • Cells tend to be microscopic. Bacterium (colored SEM;

All cells share certain characteristics. • Cells tend to be microscopic. Bacterium (colored SEM; magnification 8800 x)

All cells share certain characteristics. • Cells tend to be microscopic. • All cells

All cells share certain characteristics. • Cells tend to be microscopic. • All cells are enclosed by a membrane. cell membrane Bacterium (colored SEM; magnification 8800 x)

All cells share certain characteristics. • Cells tend to be microscopic. • All cells

All cells share certain characteristics. • Cells tend to be microscopic. • All cells are enclosed by a membrane. cell membrane • All cells are filled with cytoplasm Bacterium (colored SEM; magnification 8800 x)

• There are two cell types: eukaryotic cells and prokaryotic cells. – Eukaryotic

• There are two cell types: eukaryotic cells and prokaryotic cells. – Eukaryotic cells have a nucleus cell membrane

• There are two cell types: eukaryotic cells and prokaryotic cells. – Eukaryotic

• There are two cell types: eukaryotic cells and prokaryotic cells. – Eukaryotic cells have a nucleus. – Eukaryotic cells have membrane bound organelles cell membrane

• There are two cell types: eukaryotic cells and prokaryotic cells. – Prokaryotic

• There are two cell types: eukaryotic cells and prokaryotic cells. – Prokaryotic cells do not nucleus have a nucleus. organelles cell membrane

• There are two cell types: eukaryotic cells and prokaryotic cells. – Prokaryotic

• There are two cell types: eukaryotic cells and prokaryotic cells. – Prokaryotic cells do not nucleus have a nucleus. – Prokaryotic cells do not have membrane-bound organelles cell membrane cytoplasm

Evolution Most biologists believe prokaryotes evolved before eukaryotes for two reasons: 1. Prokaryotes tend

Evolution Most biologists believe prokaryotes evolved before eukaryotes for two reasons: 1. Prokaryotes tend to be much smaller 2. Prokaryotes are much less complex

Viruses

Viruses

Viruses • Viruses are not considered living things.

Viruses • Viruses are not considered living things.

Viruses • They have no cell membrane • Viruses are wrapped in a protein

Viruses • They have no cell membrane • Viruses are wrapped in a protein coat

Viruses • They have no cell membrane • They have no cytoplasm

Viruses • They have no cell membrane • They have no cytoplasm

Viruses • They have no cell membrane • They have no cytoplasm • They

Viruses • They have no cell membrane • They have no cytoplasm • They depend on their host for energy

Viruses • They have no cell membrane • They have no cytoplasm • They

Viruses • They have no cell membrane • They have no cytoplasm • They depend on their host for energy • They depend on their host for reproduction

Viruses Characteristics of life Characteristics of Viruses 1. Need energy for life processes. 1.

Viruses Characteristics of life Characteristics of Viruses 1. Need energy for life processes. 1. Must depend on host. 2. The ability to reproduce 2. Must depend on host. 3. Responds to the environment. 3. Does not respond to the environment. 4. Passes heritable traits through DNA or RNA