What is a cell? DEFINITION A cell is the basic unit of any organism or living thing. This means that it is the smallest “part” that is able to carry out life processes. It is what all living things are made of.

THE DISCOVERY OF CELLS: In 1655, Robert Hooke observed dead cork cells using a very basic microscope. By 1650, Anton van Leeuwenhoek and other scientists were using simple microscopes to examine many different materials. Van Leeuwenhoek discovered protozoa in 1674 and bacteria in From discoveries like these came the formation of the cell theory. In 1590, the microscope was invented by Zacharias Janssen At almost the same time, Galileo invented the telescope!

The Cell Theory When Schleiden and Schwann proposed the cell theory in 1838, cell biology research was forever changed. The cell theory and three parts and states that: All life forms are made from one or more cells. Cells only arise from pre-existing cells. The cell is the smallest form of life. THE DEVELOPMENT OF THE CELL THEORY: Cell Theory

Types of Microscopes

Arm Eyepiece Body Tube Nosepiece Objective Lenses Stage Clips Stage Diaphragm Illuminator Base Coarse Adjustment Knob Fine Adjustment Knob

Viewing cells and organisms THE COMMON HOUSE FLY Wet Mount Dry Mount

Life Processes Life processes are characteristics of living things. These are activities or processes carried out by the cells of all living things. Whether an organism is only one cell or made up of many cells, all living things: produce organisms of the same kind, obtain energy from the environment (the chemical activities involved in this are called metabolism and include processes such as respiration and excretion), move, grow and develop at some point during their life spans, and respond to stimuli in their environments.

How Big Are Cells? So what about viruses?

Cell Shapes Red blood cell amoeba Nerve cell Green algae White blood cell

Cell Function In multicellular organisms, each kind of cell does its own special job. This is known as specialization.

Classification of Organisms based on type of cells 5 Kingdoms of Organisms with cells that differ in their characteristics:Protists; Fungi; Monera; Plants; Animals Green algae Mouse cells Plant cells from a leaf Fungus cell Rod-shaped bacteria

Parts of Cells QUESTION: How does a cell, especially an organism that is only made up of a single cell, carry out all of the activities and the life processes and survive ? ANSWER: The cells have even smaller parts called organelles (tiny organs).

Golgi body nucleus cell membrane cell wall ribosomes endoplasmic reticulum lysosomes cytoplasm mitochondria vacuoles

Bibliography