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The Cell Theory Djumadi Achmad

Discovery of the Cell1665 Robert HookeExamined cork (plant tissue) using a microscopeThe little boxes he observed under the microscope reminded him of the small rooms where monks live, so he named them cells

Robert Hooke

Discovery of the Cell1673 Anton van LeeuwenhoekFirst person to observe living cells under a microscope

Anton van Leeuwenhoek

Anton van Leuwenhoek1673- Used a handmade microscope to observe pond scum & discovered single-celled organismsHe called them animalcules

He also observed blood cells from fish, birds, frogs, dogs, and humansTherefore, it was known that cells are found in animals as well as plants

150-200 Year Gap???Between the Hooke/Leuwenhoek discoveries and the mid 19th century, very little cell advancements were made.This is probably due to the widely accepted, traditional belief in Spontaneous Generation.Examples: -Mice from dirty clothes/corn husks-Maggots from rotting meat

Spontaneous Generation?Francesco Redi

19th Century AdvancementMuch doubt existed around Spontaneous GenerationConclusively disproved by Louis Pasteur

Pasteur: Ummm, I dont think so!!!+=?

Development of Cell Theory1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.

Development of Cell Theory1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.

The Cell Theory CompleteThe 3 Basic Components of the Cell Theory were now complete:1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39)2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39)3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

Modern Cell TheoryModern Cell Theory contains 4 statements, in addition to the original Cell Theory:The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.All cells are basically the same in chemical composition and metabolic activities.All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc)Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)

How Has The Cell Theory Been Used?The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as:Disease/Health/Medical Research and Cures(AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.)

Some Parting ThoughtsIt is amazing to think that the cells that make up our bodies are just as alive as we are. Humans are just an intricately designed community of cells, which must work together to survive.Cells, in my opinion, are one of the strongest cases for intelligent design by our Creator God!

MitosisThe Stages of the Cell Cycle

M stage

Mitotic StageThe nucleus and cytoplasm split to make two new cellsknown as DIPLOID cells

Every dividing tissue cell in the body is always at a stage of the cell cycle. Whether it is at :-STAGES OF MITOSISCytokinesisDiagram showing the Stages of MitosisProphaseMetaphaseAnaphaseTelophaseInterphase

ProphaseMetaphaseAnaphaseTelophaseThe Stages of MitosisInterphase

INTERPHASEAfter a cell has divided, the two new cells begin the process again,the cells at this stage are in Interphase. Cell cycle It is divided into three mini stages:- G1 S G2

PROPHASEThe chromatin (unravelled DNA) in the nucleus, condenses to form pairs of chromosomes. The centrioles move to opposite ends of the nucleus. As this is happening the nucleolus begins to break down Nuclear membrane begins to break down

METAPHASEThe spindle becomes fully developed The nuclear membrane has completely gone The chromatid pairs place themselves onto individual fibres and are aligned along the centre of the spindle

ANAPHASEThe chromatid pairs are split into two (This is done by movement of the spindle fibres)The pairs then travel to opposite ends of the spindleThe halved chromatids are now called chromosomes

TELOPHASETwo new nuclei are formed when the chromosomes reach the opposite poles of the cellThe nuclear membrane is formed- the nucleolus reappearsThe chromosomes disperse in the nucleus

EARLY MICROSCOPES Zacharias Janssen - made 1st compound microscope a Dutch maker of reading glasses (late 1500s)

Leeuwenhoek made a simple microscope (mid 1600s) magnified 270X Early microscope lenses made images larger but the image was not clear

MODERN MICROSCOPES A microscope is simple or compound depending on how many lenses it contains A lens makes an enlarged image & directs light towards you eye

COMPOUND MICROSCOPEA compound microscope has multiple lenses (eyepiece & objective lenses)

STEREOMICROSCOPEcreates a 3D image

ELECTRON MICROSCOPES More powerful; some can magnify up to 1,000,000XUse a magnetic field in a vacuum to bend beams of electronsImages must be photographed or produced electronically

Scanning Electron Microscope (SEM)Electron microscope image of a spider produces realistic 3D image only the surface of specimen can be observed Electron microscope image of a fly foot

Transmission Electron Microscope (TEM) produces 2D image of thinly sliced specimendetailed cell parts (only inside a cell) can be observed

* Click the M Stage button to find out more about what the M Stage is. If the graphics are distracting click once anywhere on the screen.

The return button will take you to the last slide viewed. The house button will take you to the main menu. *The return button will take you to the last slide viewed. The home button will take you to the contents page.* Each button next to the text will take you to the indicated page. Press the house button (top right) at any time to return to the contents page.Mitosis is the life of a cell. This cycle is split into various seasons through its life to make it easier to understand*A diagram showing the stages simplified. The mitosis in action button will show an animated version of this diagram. Although the two daughter cells shown straight after anaphase are far apart, this is simply to show that two individual cells have been produced. When in fact the daughter cells are sat very close together, which can be seen in the photographs shown on the Telophase slide. *A brief description of Interphase on the whole. The following pages go into greater depth about Interphase. The three stages follow on from each other and are in order-if these would like to be viewed then continue with the forward button. Alternatively an animated diagram can be viewed of the cell cycle, by clicking on the cell cycle button. Interphase is the time lapse stage between the end of telophase and the beginning of prophase. The cell is recovering its body mass and preparing for division once again, at the same time. A cell at interphase can be seen in the photograph. This could be mistaken for a cell at early prophase as there is only slight differences between the two, however the large nucleus is an indication of its stage.*The photographs are of a cells at their resting states. The diagram is indicating the chromosomes condensing during prophase. Prophase is the first stage of mitosis, it prepares the cell for the next stage- Metaphase, by condensing the unravelled DNA into a helix which can be split into its two halves.The chromatin begins to condense to form chromosomes. Each chromosome has already replicated itself, fprming two sister chromatids which contain exactly the same genetic information. This could, however not be true if a mutation has occurred. Other events occuring in the cell are; the nucleolus begins to break down so the genetic information can be equally distributed between the two daughter cells. The nucleolus completely disappears because the genetic information is dispersed as condensing chromosomes within the cytoplasm. The contrioles (Points of the spindle) move to opposite ends of the nucleus as the spindle begins to form. The nuclear membrane begins to break down so there is no longer a nucleus as such in the parent cell.

*The information, I, will take you to a slide about the spindle and what it is made of.The dark area within the photographed cells are the developed spindles and is simplified with the diagram below it. Metaphase literally means middle stage, it is the moment before the chromosomes reach opposite ends of the cell at anaphase. The spindle can be seen in the green picture, and the chromosomes arranged upon it.The easy way to identify the start of metaphase is the disappearance of the nuclear membrane, this breaks up into individual vesicles, it then joins up onto the endoplasmic reticulum (so is not just lost within the cytoplasm).The spindle is now fully developed and takes the place where the nucleus was.The most obvious stage of metaphase;- the chromatid pairs align themselves along the centre of the spindle after being attached to the spindle fibres themselves. *The photograph shows the cell at the proceeding stage of mitosis-anaphase and is highlighted to show the direction in which the spindle is moving.The aligned chromatid pairs are pulled apart from the centre of the spindle due to movement of the microtubule spindle fibres. They are pulled to opposite poles of the cell.This is the most recognisable event during mitosis, it can be seen clearly in the films featured in the movies section which can be accessed through the contents page. *The photographed cell now shows telophase. Two cells stuck next to each other. The forward button will now take you to a slide about Cytokinesis, or the home button will take you back to the contents page.The chromosomes have reached opposite ends of the spindle, they unravel and disperse into the cytoplasm so cannot be seen.The nuclear membrane reforms.The nucleolus reappears- much of the events that happen during telophase are the opposite of the events that happen during prophase.