Download Cells “The Building Blocks of Life”

Cells
“The Building Blocks of Life”
What is a Cell?
• The structural and functional units of all
living organisms.
• Living matter enclosed by a barrier that
separates it from the exterior environment.
• What is a theory?
– A set of statements or principles devised to
explain a group of facts or phenomena
– Based on limited information or knowledge
– Verified or falsified through experimentation
History of Cell Theory
• Robert Hooke - 1665
– Used microscope to study cross-sections of
cork which he called “cells”.
• Anton van Leeuwenhoek 1674
– Used a simple microscope to describe tiny
cells and bacteria
• Theodor Schwann - 1839
– Concludes that all animals are made of cells
Cell Theory
1)
All living things are composed of
cells
2) Cells are the basic units of
structure and function in living
things
3) All cells come from pre-existing
cells
Exceptions: Viruses
- Not composed of cells
- Cannot survive without a host
More about cells…
• Cells fall into two categories
– Eukaryotes – Plants, animals, fungi
• Cells that contain organized nuclei (nucleus)
– Prokaryotes - Bacteria
• Cells that contain a non-organized nuclei (nucleus)
Nuclues
• Nucleus is a large membrane-enclosed
structure that contains the cell’s genetic
material (DNA)
• The Nucleus controls most of the cell’s
activities!!!
• DNA is like the instructions for your cell