End Show Slide 1 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular.

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Copyright Pearson Prentice Hall

7-1 Life Is Cellular

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The Discovery of the Cell

Early Microscopes

In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material.

Cork looked like thousands of tiny, empty chambers.

Hooke called these chambers “cells.”

Cells are the basic units of life.

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Hooke’s Drawing of Cork Cells

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Scientists and their thoughts…..

In 1838, Matthias Schleiden concluded that all plants were made of cells.

In 1839, Theodor Schwann stated that all animals were made of cells.

In 1855, Rudolph Virchow concluded that new cells were created only from division of existing cells.

These discoveries led to the cell theory.

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The cell theory (CAN) states:

1. Cells are the basic units of structure and function in living things.

2. All living things are composed of cells.

3. New cells are produced from existing cells.

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How can we look at cells?


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Exploring the Cell

Remember hearing about the Electron Microscopes?

Reveal details 1000 times smaller than those visible in light microscopes.

Electron microscopy can be used to visualize only nonliving, preserved cells and tissues.

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Exploring the Cell

Transmission electron microscopes (TEMs)

• Used to study cell structures and large protein molecules

• Specimens must be cut into ultra-thin slices


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Exploring the Cell

Scanning electron microscopes (SEMs)

• Produce 3D images of cells


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Prokaryotes and Eukaryotes

Cells are classified into two categories, depending on whether they contain a nucleus.

The nucleus is a large membrane-enclosed structure that contains the cell's genetic material in the form of DNA.

The nucleus controls many of the cell's activities.


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• Eukaryotes are cells that contain nuclei.

• Prokaryotes are cells that do not contain nuclei.


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What are the characteristics of prokaryotes and eukaryotes?

Get out your Venn Diagram

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Prokaryotes

Prokaryotes genetic material is not contained in a nucleus.

•Do not have membrane bound organelles.

•Smaller and simpler than eukaryotic cells.

•Examples include: Bacteria and blue-green algae.

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Eukaryotes

Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell.

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•Larger and more complex than prokaryotic cells.

•Contain dozens of structures and internal membranes (organelles).

•Highly specialized.

•Plants, animals, fungi, and protists (unicellular organisms) are eukaryotes.

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Similarities of Pro vs. Euk

• Both contain DNA

• Both are filled with cytoplasm and contain ribosomes

• Both have a plasma membrane.


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7-1The cell theory states that new cells are produced

from

• nonliving material.

• existing cells.

• cytoplasm.

• animals.


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7-1The person who first used the term cell was

• Matthias Schleiden.

• Lynn Margulis.

• Anton van Leeuwenhoek.

• Robert Hooke.


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7-1Which organism listed is a prokaryote?

• protist

• bacterium

• fungus

• plant


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7-1One way prokaryotes differ from eukaryotes is that

they

• contain DNA, which carries biological information.

• have a surrounding barrier called a cell membrane.

• do not have a membrane separating DNA from the rest of the cell.

• are usually larger and more complex.


End Show Slide 1 of 31 Copyright Pearson Prentice Hall 7-1 Life Is Cellular.

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