Cell TheoryCell Cell Membrane Cytoplasm DNA Ribosome Nucleus

Cell Theory

• The cell is the basic unit of structure and function in every living thing.

• All cells grow and divide transmitting genetic information from one generation to the next.

• The invention of the microscope aided in the understanding of the cell theory.

Cell

Cell• The cell was first discovered by English scientist

Robert Hooke in 1665. • He noticed that thin slices of cork looked like the

small rooms or cells.

Cell comes from the Latin word Cellulae, which means small room.

Cell Theory Anton van Leeuwenhoek was the first scientist

to use a microscope to see tiny living organisms in a drop of water.

The invention of microscopes changed the way biologists understood nature.

Animated Video Online: Leeuwenhoek (6.5 min)

Cell Theory German physiologist Theodor Schwann and

German botanist Matthias Schleiden (1839)... "All living things are composed of cells and cell products."

Where do cells come from?

Cell Theory

In 1864 Louis Pasteur confirmed that spontaneous generation was not possible with his pasteurization experiments.

Rudolf Virchow German physician (1855)“Where a cell exists there must have been a preexisting cell…”

The Cell Theory The cell theory is one of the fundamental

concepts of biology. The cell theory states:

• All living things are composed of one or more cells. • Cells are the basic unit of structure and function in

living things. • New cells are produced from existing cells.

Basic Cell Structures Cells differ in size, structure, and function, but

every cell has the following structures: !

Plasma Membrane Cytoplasm DNA Ribosomes

Basic Cell Structures The plasma membrane (cell membrane) is a

thin, flexible barrier around the cell.

Basic Cell Structures The cytoplasm (cytosol) is the fluid material

inside the cell membrane that contains all the cell structures.

Basic Cell Structures DNA (deoxyribonucleic acid) is the molecule that

contains the instructions for building the proteins that make up the cells.

Basic Cell Structures Ribosomes are the protein-making machines of

the cell. They translate genetic information from the DNA into the cell parts.

Prokaryotes and Eukaryotes Cells are divided into two main categories,

eukaryotes and prokaryotes. – Eukaryotes have a nucleus – Prokaryotes do not have a nucleus.

Karyo is Latin for “kernel” or “nucleus” Eu means “good” or “true” Pro means “before”

Nucleus The nucleus controls most cell processes, and

stores the genetic material, DNA.

Prokaryotes Prokaryotes are small single-celled organisms

that do not contain nuclei. Includes all bacteria.

Eukaryotes Eukaryotes include single or multicellular

organisms with specialized membrane bound structures called organelles.