Cell Structure and Function Notes
BIOLOGY 12- CELL STRUCTURE & FUNCTION Chapter Notes
THE CELL THEORY
• Although different living things may be as unlike as a violet and an octopus, they are all built in essentially the same way. The most basic similarity is that all living things are composed of one or more cells. This is known as the
• our knowledge of cells is built on work done with microscopes
• English scientist Robert Hooke in 1665 first described cells from his observations of cork slices. Hooke first used the word “cell”.
• Dutch amateur scientist Antonie van Leeuwenhoek discovered microscopic animals in water
• German scientists Schleiden and Schwann in 1830’s were first to say that all organisms are made of one or more cells.
• German biologist Virchow in 1858 stated that all cells come from the division of pre-existing cells.
• Cells are the building blocks of life.
The Cell Theory can be summarized as:
1. All living organisms are made up of one or more
2. The cell is the basic of life
3. All cells come from the of pre-existing cells
• cells come in many shapes and sizes, although most are microscopic: o Most cells are small, about 0.001 cm in length (1/100 of a mm, or 10 μm). o the smallest cells of the microorganism mycoplasma are 0.3 μm in size o Some cells are large. E.g. some giant algal cells may be several centimeters long. A chicken’s egg is a single cell. o 40,000 red blood cells would fill the letter “O” on a page of type. You produce about 2.5 million new red blood cells every second! Each square cm of your skin contains about
150,000 skin cells. o Human beings are composed of about 50 to 100 cells.
• Cells carry on all the processes associated with life, such as reproducing and interacting with the environment.
• The study of cell structure includes the fields of (for cells) and HISTOLOGY
(for tissues), whereas the function of cells is studied in CELL ,
BIOCHEMISTRY, and CYTOGENETICS.
• The first