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Introduction to Cells

Introduction to Cells. History of cells. Discovery: Cells were discovered in 1665 when English scientist Robert Hooke used a primitive microscope to look at a slice of cork.

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Introduction to Cells

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  1. Introduction to Cells

  2. History of cells • Discovery: • Cells were discovered in 1665 when English scientist Robert Hooke used a primitive microscope to look at a slice of cork. • He noticed a honeycomb pattern and he called the individual spaces “cells” because they reminded him of small jail cells. • The Latin word cellula means small compartment. • These cells were all dead so he did not see anything inside the cells.

  3. Anton van Leeuwenhoek: A Dutch scientist observed the first living cells of bacteria and protozoans under a microscope in 1670. • Matthias Scleiden: A German scientist was the first to conclude that all plant tissue is composed of cells in 1838. • Theodor Schwann: A German scientist concluded that all animal tissue is made of cells. • The Cell Theory was developed from these observations. • Cell Theory: The cell is the basic unit of structure in every living thing.

  4. Tools to see the cells • Light Microscope: Uses two or more glass lenses to magnify images. The best can magnify up to 2000 times. Ours magnify up to 400 times. If the Earth were a cell we would be able to see 143, 172 square miles (331 times the size of the reservation). • Electron microscope: Uses a beam of electrons to view things at the molecular level. 2 million times the normal size. If the Earth were a cell we could see 28 square miles (A 15th of the reservation)

  5. Two types of cells Eukaryotic Prokaryotic Do not have membrane bound structures Do not have a nucleus Usually only single celled Bacteria • Have membrane bound structures (organelles) • Have a nucleus • Made of one or many cells • Plant and animal cells

  6. The Cell Cycle

  7. The circle is used to represent many things in biology. • The cell cycle is a circle that represents the life of cells. • The cycle • G1 : First growth phase. The cell grows in size and makes more cellular parts (not DNA) • S: Synthesis phase: The cell reproduces DNA and makes copy of each chromosome • G2: Second growth phase: The DNA is checked for problems and materials needed for division are made. • M: Mitosis phase: The cell divides including mitosis and cytokinesis to form two new cells.

  8. Not all cells continue the cell cycle. • For example: Nervous system cells stop division after development early in our lives. • This is why damage to the spinal cord can leave us paralyzed for life. • These cells cannot repair themselves.

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