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THE CELL HISTORY

Cells vary in size, shape, and function but there are parts and characteristics common to all of them.

Certain cells produce secretions which are used to promote health and improve food production

The discovery of cells and their structures was scientific output of the simple microscope discovered in the 17th century by Anton Van Leeuwenhoek and other amateur scientist.

Cells were discovered by Robert Hooke in 1665.

Around 1665 he observed from a thin slice of cork, and other plant materials.

There he observe box-like compartments in the cork. Hooke thought they were small rooms or cells of old monasteries, he called this room-like structures cells.

The central part of the cell, the nucleus was discovered by Robert Brown in 1883.

In 1838, Matthias Schleiden stated that cells are unit structures of plants, while in 1939, Theodor Schwaan, a zoologist said that cells are unit structures of animals.

MATTHIAS THEODOR SCHLEIDEN SCHWAAN

THE CELL THEORY

In the late 1830’s two German scientist Matthias Schleiden, a plant biologist, and Theodore Schwaan an animal biologist, worked on various organism-Schleiden on plants, and Schwaan on animals.

Published in 1838 an 1839 respectively, Their dual findings contained the first clear definition of the cell theory.

MATTHIAS THEODOR SCHLEIDEN SCHWAAN

In 1858, Rudolf Virchrow, a Viennese pathologist argued that cells were capable of independent existence. Virchrow added that new cells arise only from pre-existing cells . This is the theory of biogenesis which is opposed to the theory of spontaneous generation.

Biogenesis holds that under present conditions on earth, life can only came from life.

“new cells arise

only from pre-existing

cells”

The words of Virchrow, Schleiden and Schwaan and a host of other scientists helped form the so-called cell theory. The major priciples contained in the cell theory are the following.

1. Living things are composed of one or more units called cells.

2. Cells are capable of independent existence

3. New cells on arise from pre-existing cells.

PROKARYOTIC VS. EUKARYOTIC

Eukaryotic cells-

a distinct nucleus enclosed by a membrane, except for RBC and plant cells like vessels, tracheid and phloem elements w/c when matured also lack nucleus and cytoplasm, eukaryotic cell make up most of an organisms body such as amoeba and paramecium.

Prokaryotic cells-

well-defined, membrane-enclosed nucleus and organelles such are called prokaryotic

EUKARYOTIC CELL

Prokaryotic Eukaryotic

No Nucleus w/ Nucleus

No membrane-enclosed organelles

w/ membrane-enclosed organelles

Have one chromosomes Have chromosomes in pairs

Have no cellulose in cell walls

Have cellulose in cell walls

Have smaller Ribosomes Have larger Ribosomes

No movement of cellular materials w/in the cell

Cellular materials often appears to move (streaming) w/in the cell

Have simple cytoskeleton Have Cytoskeleton

Have solid Flagella Have complex tubular Flagella

Do not undergo cell division

Undergoes cell division by mitosis

THE COMMON CELL ORGANELLES

A cell is enveloped in a special barrier. In animals it is a cellular membrane, while in plants it is a cell wall that keeps all the cells and its intricate system of working parts intact. Biologist call these cellular parts as organelles

CELL ORGANELLES FOUND IN BOTH PLANT & ANIMAL CELLS

Cell Organelles

Cell membrane-

The first line of an animal cell is its cell membrane. Cell membrane is made up of a double layer of fat molecules.

Nucleus(plural, nuclei)-

The nucleus is the control center of the cell. It acts like the brain of the cell. The nucleus is a spherical body in the cell that acts as its control center.

Cytoplasm-

all organelles outside the nucleus are embedded in the cytoplasm, a viscous jelly-like substance.

Endoplasmic Reticulum (ER)-

Endoplasm means “w/in the cytoplasm” and reticulum means “little net”

There are two types of Endoplasmic Reticulum,

the Rough ER and the Smooth ER

TWO TYPES OF ENDOPLASMIC RETICULUMSmooth ER-

the smooth ER is a network of folded and convoluted tubules located near the nucleus. It contains molecules called enzymes that synthesize some hormones and estrogen.

Rough ER-

The Rough ER is also a network of folded and convoluted sacs, its rough appearance is attributed to the ribosomes that stud the folded structures emanating from the nuclear membrane.

Golgi apparatus (pronounced “goal-gee”)-

the Golgi apparatus looks like a stack of pancakes located near the nucleus. It function as the packaging and distribution center of the cell.

Mitochondrion (plural, mitochondria)-

the mitochondrion is referred as the “powerhouse of the cell”

It has outer and inner membrane and a distinctive elongated shape similar to a hotdog.

Ribosome-

The ribosome is a small organelle packed with RNA. It is the site of protein synthesis. The rough ER is studded with ribosome.

CELL ORGANELLES FOUND IN AN ANIMAL CELL BUT NOT IN A PLANT CELL

Lysosome-

Lysosome are circular vesicles that contain digestive enzymes. Their main job seems to be, to eat! The lysosomes digest not only cell nutrients but also break down cellular waste into smaller molecules w/c the cell can use.

Centriole-

centrioles are a branch of microtubules arranged at right angle to each other.

Cilia or flagella (singular, cilium, flagellum)-

The cilium and flagellum are used as means of locomotion or travel of unicellularorganisms.

Vacuoles-

The Vacuoles in an animal cell are the smallest in size and more in number than that found in a plant cell. Vacuoles act as storage areas of cell nutrients.

CELL ORGANELLES FOUND IN PLANT CELLS BUT NOT IN ANIMAL CELLS

Cell Organelles

Cell wall-

aside from a cell membrane, a plant cell is surrounded by rigid cell wall made of cellulose. The plant cell wall protect the cell and allows it to take in nutrients and expel waste materials.

to produce

Chloroplast-

Plants are able to produce food by converting carbon dioxide from the air, and water into carbohydrates. The process is powered by the energy from the sun and is called photosynthesis.

Cell sap Vacuole-

in each plant cell there is one large vacuole called the cell sap vacuole that acts as a centralized storage of water.

/SUMMARY/

Robert Hooke was the first to see a cell and the name “cell” to the building block of living organism.

Anton Van Leeuwenhoek is known as the “Father of Microscopy”. His model of the microscope paved the way the study of microscopic organism. He was the first to see a bacteria.

The cell is the basic unit of life. It was an outer covering (cell wall for plant cells and cell membrane for animal cells), a central control (nucleus), and servicing parts (organelles).