Cells: The Evolving Concept of Life PDF

# CELLS - Cells are the basic units of structure and function in living things. - Just like bricks are the building blocks of a house or school, cells are the building blocks of life. - Because you are alive, you are made up of cells. One square centimeter of your skin's surface contains over 100...

# CELLS - Cells are the basic units of structure and function in living things. - Just like bricks are the building blocks of a house or school, cells are the building blocks of life. - Because you are alive, you are made up of cells. One square centimeter of your skin's surface contains over 100,000 cells. # HISTORY OF THE CELL - Around the year 1590, two Dutch lens makers by the name of Hans and Zacharias Janssen invented the first compound microscope when they put two of their lenses together in a tube. - In 1665, an English scientist, Robert Hooke, discovered and came up with the name "cells'' while looking through a microscope at a piece of cork. - Supposedly, the cork (which was made of dead oak tree tissues) reminded him of the small rooms that the monks lived in at the monasteries. # HISTORY OF THE CELL - Zacharias Jansen - Robert Hooke - Robert Hooke's cells # HISTORY OF THE CELL - Not long after Hooke (around 1683), a Dutch amateur scientist by the name of Anton Van Leeuwenhoek observed some of the first living cells under a simple (1 lens) microscope. - He named these small organisms "animalcules". - It is now believed that some of the living cells he saw were actually protozoa. # MICROSCOPE VIEW OF CELLS - Anton Van Leeuwenhoek - first to see living cells. - Improved design, and was able to view red blood cells and bacteria. - Called them "animalicules". # THE DEVELOPMENT OF CELL THEORY - In 1838 and 1839, a German botanist by the name of Matthias Schleiden and German zoologist by the name of Theodore Schwann viewed plants and animals under a microscope and discovered that plants and animals are both made of cells. - In 1855 a Prussian (modern day German) physician by the name of Rudolph Virchow collaborated his ideas with the other two scientists and they developed the Cell Theory. # SCIENTISTS OF CELL THEORY - Theodore Schwann - zoologist who observed that the tissues of animals had cells (1839) - Mattias Schleiden - botanist who observed that the tissues of plants had cells (1845) - Rudolf Virchow - reported that every living thing is made up of cells, and that these cells must come from other cells. In 1855, a German doctor, Rudolf Verchow (FURkoh) proposed that new cells are formed only from existing cells. "All cells come from cells" wrote Virchow. The observations and conclusions of Hooke, Leeuwenhoek, Schleiden, Schwann, Virchow, and others led to the development of the cell theory. # CELL THEORY - The ideas of these three men led to the creation of the cell theory. These are the three main principles of cell theory. - All living organisms are made up of cells. - Cells are the most basic unit of life. - Cells only come from the division of pre-existing cells. In other words, spontaneous generation of cells does not occur. # TERMS - **Cell** - the smallest unit that can carry on the processes of life. - **Unicellular** - consists of only one cell - **Multicellular** - consists of more than one cell # BASIC CELL STRUCTURES - **Cell Membrane** - outer boundary - **Nucleus** - control center - **Cytoplasm** - stuff between membrane & nucleus # BASIC TYPES OF CELLS - Cells come in a variety of shapes and sizes, but all cells share some basic characteristics. - One thing that all cells have in common is a plasma (cell) membrane. - The cell membrane is a boundary which allows things into and out of the cell. | Cell Type | Description | Size | |---|---|---| | Prokaryotic | Unicellular organisms like bacteria. Notice the DNA is not found in a nucleus and organelles are absent (except ribosomes). | 0.1-10 µm | | Eukaryotic | Cells with a membrane-bound nucleus and membrane-bound organelles. Animals, plants, protists (like paramecium and amoeba), and fungi are all eukaryotic organisms. | 10-100 µm | # DIFFERENCES IN CELL TYPES - All cells fall into one of two categories. - **Eukaryotes** – Cells with a membrane-bound nucleus and membrane-bound organelles. - **Prokaryotes** – Cells without a membrane-bound nucleus and membrane-bound organelles. - A nucleus is the central organelle of a cell that contains the genetic material (DNA). - **Organelles** are like organs for the cell. They are special structures that perform vital functions necessary to the cell. # PROKARYOTIC CELLS - Prokaryotic cell – Unicellular organisms like bacteria. Notice the DNA is not found in a nucleus and organelles are absent (except ribosomes). # EUKARYOTIC CELLS - Eukaryotic cells have a membrane-bound nucleus and membrane-bound organelles. - Animals, plants, protists (like paramecium and amoeba), and fungi are all eukaryotic organisms.