Discovery and Development of the Cell Theory: Hooke, Schleiden, Schwann, and Virchow, Lecture notes of Science education

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The Cell

Theory

The Cell Theory 1.

The Discovery of the microscope helped early scientist to

Understand the structure and function of cells. In 1665, Robert Hooke first viewed the cells of the cork plant using The microscope he built. Hooke observed that, when seen Under the microscope, the thin slice from the cork plant had Tiny and empty compartments similar to those of a honey- Comb. He identified the empty compartments as the dead Cells of the plant. He named them cellulae, which meant “small rooms” but later used the shorter word cell ------------- An artist’s rendition of Hooke’s view of Cork plant cells through microscope he Built. --------------------------------

The Cell Theory 1.

The following year, German physiologist Theodor Schwann expanded on the cell theory as he showed how animal tissues are also made up of individual Cells. In 1855, Rudolf Virchow , a German doctor and one of the prominent physicians of the 19 th century, Stated that a new cell form from a previously Existing cell. Schleiden and Virchow unified the concept of cell structure that Hooke had Initiated Theodor Schwann (1810 – 1882) and Rudolf Virchow (1821 – 1902 )

Cells

Cells 1.

A cell is made up of carbohydrates, lipids, proteins, nucleic acids, salts, and water. There materials are essential to the different biochemical pathways that form the molecular structures of the cell. Cells can exchange materials and energy with their environment. Although cells can get and exchange materials in many ways, the y have to convert the materials to form a product, and to use the convert the energy. Cells store energy in the form of adenosine triphosphate or ATP

Cells 2.1 How Cells Carry Out Functions Required for Life

Organisms are made up of cells. Organisms may be unicellular or

Single-celled such as an amoeba. Organisms that are multicellular, such as animals and plants, are composed of many specialized cells that perform specific functions and also work together to meet the needs of the organisms and its cells Blood cells are specialized cells Of multicellular organisms A Euglena , A protist, is an Example of a unicellular organism

Cells 2.3 How Cells Carry Out Functions Required for Life

Cells carry out many functions required for life. For example, to reproduce, they grow and divide, thereby producing cells. To reproduce, cells take in nutrients which they use to provide energy for the processes that they do. The following are functions required for life

Cells 2.4 How Cells Carry Out Functions Required for Life

Respiration is a set of metabolic reactions and processes which

take place in the cells

Regulation is the control and

coordination of body activities through the nervous system

Cells 2.6 How Cells Carry Out Functions Required for Life

Excretion is the removal of waste

s produced by cellular activities

Growth is the increase in size of organisms as

result of increase in number and size of cells

Nutrition is the process by which

organisms take in food from their environment

Cells 2.7 How Cells Carry Out Functions Required for Life

Transport is the process

by which materials needed by the cell or an organism are taken by the organism through absorption and circulation

Synthesis is the process by which

cells combine chemically simpler and smaller substances to form various complex substances

Photosynthesis 1.

Plants and animals are

similar in their use of energy within th e cells for energy transformation processes necessary for life. Plant cells have chloroplasts which contains chlorophyll , a green pigment that lends it green color to the plant. Chloroplasts are the food producers of the cell. These are found in plant cells and in some protists such as algae. Animal cells do not have chloroplasts.

Photosynthesis 1.

Chloroplasts convert the

sun’s light energy into sugars ( glucose and other carbohydrates) that can be used by the cell. This process is called photosynthesis.

Photosynthesis 1.

Plants use photosynthesis to produce food and energy by converting light energy in to chemical energy of sugars and other organic compounds. When the light energy of the sun strikes chloroplasts and chlorophyll molecules, light energy is converted into chemical energy found in ATP and in nicotinamide adenine dinucleotide phosphate (NADPH). ATP is a high-energy molecule within the cells that stores and transports the chemical energy an organism needs for metabolism. It is present in the cytoplasm and nucleoplasm of every cell. All physiological mechanisms that require energy to function obtain chemical energy directly form the stored ATP

Photosynthesis 1.

Those energy-rich

compounds move into the stroma where enzymes fix the carbon atoms from carbon dioxide (CO 2 ). The molecular reactions eventually create sugar (C 6 H 12 O 6 ) and oxygen (O 2 ). Plants and animals then use the sugars (glucose) for food and energy