Structure and Function of The Cell Reference: Modern Biology CHAPTER 4

Introduction to the Cell Modern Biology Chapter 4 Sect. 4 – 1 Pgs

BIG IDEAS **Cells distinguish living things from all other matter – they are the “building blocks of life” **A cell is the smallest unit that can carry on all the processes of life. **There is a relationship between a cell’s function and its structure (size and shape)

Bill Nye The Science Guy!

Introduction to CELLS Discovery of the CELL The Microscope - the discovery of the microscope in the early 1600’s. –Robert Hooke – 1665 – Viewed “little boxes” – coined the name “cell”. –Anton van Leeuwenhoek – 1673 – Viewed the first living organisms-protozoa, bacteria – “animalcules” –Matthias Schlieden – 1838 – Concluded that all plants are made of cells –Theodor Schwann – 1839 – Concluded that every animal is made of cells –Rudolf Virchow – Concluded that cells can only come from other living cells

Observations began by Hooke & van Leeuwenhoek and later confirmed by Schleiden, Schwann and Virchow were organized by scientists into a unified theory known as: THE CELL THEORY THE CELL THEORY 1.All living things are composed of cells. EXPLANATION.A living being is either a cell or is made up of cells. 2.Cells are the basic unit of structure and function in an organism. EXPLANATION. Any part of cell cannot be called living. It is the whole cell which can be called living. In other words it is the smallest living unit. 3.All cells come from the reproduction of other cells. EXPLANATION. New cells arise by cell division of pre-existing cells. This holds good for all cells, but not for the first cell that arose by chemosynthesis.

Watch this video onvideo The Cell Theory !

THE CELL Cell - the smallest unit that can carry out all the processes of life (take in nutrients, get rid of waste, etc) –Every living thing is made of one or more cells. Unicellular-complete living thing made of only one cellUnicellular-complete living thing made of only one cell –Example: amoeba, paramecium Multicellular-living thing made of more than one cellMulticellular-living thing made of more than one cell –Example: frogs, trees, coral, mushrooms, humans

Unicellular exact clones Unicellular – Each new cell is identical to the parent. All developing organisms are exact clones of their parents. Multicellular Multicellular – Cells become different (differentiation) from each other as they multiply. All developing multicellular organisms are a combination of two parents, but are different from them – not clones. DIFFERENTIATION

Egg cells are the biggest single cells …

eggs, Just like one of these eggs, each of you began as a single cell…

Cell Diversity Let’s watch a video on Why are cells small? Why are cells small?

DO NOW Respond to the following in your notebook: Why do cells divide before they get too big?

Cell Diversity Not all cells are alike…they can differ in size shape and internal organization *SIZE: *SIZE: Cells come in all sizes, but most cells are very small (microscopic) - Cell size is limited by the ratio of volume to surface area. Examples: –Longest-giraffe nerve cell (2 meters) –Smallest-bacteria (0.2 micrometers) –Largest - egg cells

Some differently sized cells … The cell body of a motor neuron is approximately 100 µm (0.1 millimeter) in diameter and the axon is about 1 meter (1,000 millimeter) in length. The bacterium, Haemophilus influenzae (it was once thought to cause the flu) is among the smallest bacteria - 0.5– 2.0 µm in length - which is about the smallest object that can be seen through a light microscope.

*SHAPE –Cells have a shape (structure) to fit their function Examples: –Nerve cell-has extensions (axons) to allow it to transmit and receive nerve impulses –Skin cells-flat to cover body surface –White blood cells-can change shape to squeeze into spaces to isolate bacteria that invade the body.

Cell Diversity Some differently shaped cells

*INTERNAL ORGANIZATION Cells contain internal structures that help it carry out all of its functions. In other words : “FORM FITS FUNCTION” For example - Every cell in your body contains organelles (structures that have specific functions). –Just like organs in the body, each organelle contributes in its own way to helping the cell function well as a whole. Examples: –Cell Membrane – surrounds the cell –Nucleus – contains most of the cells genetic material; directs most of the cells activities

“Form Fits Function” Watch this VideoVide How does the Form (shape / structure) of a cell help it to do its Function (job)?