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Chapter 7 Cell Strucutre and Function

Ngud
Course

College Geometry (MAT 115)

4 Documents
Students shared 4 documents in this course
Academic year: 2019/2020
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This document has been uploaded by a student, just like you, who decided to remain anonymous.
Rowan College of South Jersey

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Cell: basic unit of all forms of life Cell theory: fundamental concept of biology that states that all living things are composed of cells; that cells are the basic units of structure and function in living things; and that new cells are produced from existing cells.

Cell membrane: thin, flexible barrier that surrounds all cells; regulates what enters and leaves the cell

Nucleus: the center of an atom, which contains the protons and neutrons; in cells, structure that contains the cell's genetic material in the form of DNA.

Eukaryotic: organism whose cells contain a nucleus

Prokaryote: unicellular organism that lacks a nucleus

Vocabulary:

Key Questions

○ All living things are made up of cells. ○ Cells are the basic units of structure and function in living things. ○ New cells are produced from existing cells.

  • The cell theory states:

What is the cell theory?

Most microscopes use lenses to magnify the image of an object by focusing light or electrons.

•

How do microscopes work?

  • Prokaryotic cells do not separate their genetic material within a nucleus.
  • In eukaryotic cells, the nucleus separates the genetic material from the rest of the cell.

How are prokaryotic and eukaryotic cells different?

The smallest unit of any organism- the cell.

The Discovery of the Cell

Without the instruments to make them visible, cells remained out of sight and, therefore, out of mind for the most of human history. All of this changed with a dramatic advance in technology- the invention of the microscope.

Early Microscopes

In 1665, Englishman Robert Hooke used an early compound microscope to look at a nonliving thin slice of cork, a plant material. Under the microscope, cork seemed to be made of thousands of tiny empty chambers. Hooke called these chambers "cells" because they reminded him of a monastery's tiny rooms, which were called cells. The term cell is used in biology to this day. Today we know that living cells are not empty chambers, that in fact they contain a huge array or working parts, each with its own function, (organelle.) In Holland around the same time, Anton van Leeuwenhoek, used a single lens microscope to observe pond water and other things. To his amazement, the microscope revealed a fantastic world of tiny living organisms that seemed to be everywhere, in the water he and his neighbors drank, and even in his own mouth. Leeuwenhoek's illustrations of the organisms he found in the human mouth-- which today we call bacteria.

Cork under microscope: first "Cells"

Robert Hooke:

Robert Hooke's Microscope

Robert Hooke

Anton van Leeuwenhoek:

Leeuwenhoek's Microscope

7 Life is Cellular

Sunday, December 16, 2012 1:07 PM

Leeuwenhoek's Microscope

Freshwater 'animalcules' viewed by Leeuwenhoek's microscope

Anton van Leeuwenhoek

The Cell Theory

Soon after van Leeuwenhoek, observations by scientist made it clear that cells are the basic units of life. In 1813, German botanist Matthias Schleiden concluded that all plants are made up of cells. The next year, German biologist Theodor Schwann stated that all animals are made of cells. In 1855, German physician Rudolf Virchow concluded that new cells can be produced only from the division of existing cells, confirming a suggestion made by German Lorenz Oken 50 years earlier. These discoveries, confirmed my many biologist, are summarized in the cell theory, a fundamental concept of biology. The cell theory states: * All living things are made up of cells. * Cells are the basic units of structure and function in living things. *New cells are produced from existing cells.

Matthias Schleiden concluded that all Plants are made of cells.

Theodor Schwann stated that all Animals are made up of cells.

Rudolf Virchow concluded that New cells can be produced only From the division of existing cells

Lorenz Oken

Cell theory:

Electron Microscope

Light microscopes can be used to see cells and cell structures as small as 1 millionth of a meter-- certainly pretty small! But what if scientists want to study something smaller than that, such as a virus or DNA molecule? For that, they need electron microscopes. Instead of using light, electron microscopes offer much higher resolution than light microscopes. Some types of electron microscopes can be used to study cellular structures that are 1 billionth of a meter in size. There are two major types of electron microscopes: transmission and scanning. Transmission electron microscopes make it possible to explore cell structures and large protein molecules. But because beams of electrons can only pass through thin samples, cells and tissues must be cut into ultrathin slices before they can be examined. This is the reason that such images often appear flat and two dimensional. In scanning electron microscopes, a pencil-like beam of electrons is scanned over the surface of the specimen. Because the image is formed at the specimen's surface, samples do not have to be cut into thin slices to be seen. The scanning electron microscope produces stunning three-dimensional images of the specimen's surface.

Pollen grains Electrons are easily scattered by molecules in the air, which means samples must be placed in a vacuum to be studied with an electron microscope. As a result, researchers must chemically preserve their samples. Electron microscopy, then, can only be used to examine nonliving cells and tissues.

Prokaryotes and Eukaryotes

Cells come in an amazing variety of shapes and sizes.

Although typical cells range from 5 to 50 micrometers in diameter, the smallest Mycoplasma bacteria are only 0 micrometer across, so small that they are difficult to see under even the best light microscope. In contrast, the giant amoeba Chaos chaos can be 1000 micrometers (1 millimeter) in diameter, large enough to be seen with unaided eye as a tiny speck in pond water. Despite their differences, all cells, at some point in their lives, contain DNA, the molecule that carries biological information. In addition, all cells are surrounded by a thin flexible barrier called a cell membrane. (The cell membrane is sometimes called the plasma membrane because many cells in the body are in direct contact with the fluid portion of the blood-- the plasma.) There are other similarities as well, as you will learn in the next lesson. Cells fall into two broad categories, depending on whether they contain a nucleus. The nucleus (plural: nuclei) is a large membrane- enclosed structure that contains genetic material in the form of DNA and controls many of the cell's activities. Eukaryotes are cells that enclose their DNA in nuclei. Prokaryotes are cells that do not enclose DNA in nuclei.

Prokaryotes

Prokaryotic cells are generally smaller and simpler than eukaryotic cells, although there are many exceptions to this rule. Prokaryotic cells do not separate their genetic material within a nucleus. Despite their simplicity, prokaryotes carry out every activity associated with living things. They grow, reproduce, respond to the environment, and, in some cases, glide along surfaces or swim through liquids. The organisms we call bacteria are prokaryotes.

Eukaryotes

Eukaryotic cells are generally larger and more complex than prokaryotic cells. Most eukaryotic cells contain dozens of structures and internal membranes, and many are highly specialized. In eukaryotic ells, the nucleus separates the genetic material form the rest of the cell. Eukaryotes display great variety: some, like the ones commonly called "protists," live solitary lives as unicellular organisms; others form large, multicellular organisms- plants, animals, and fungi.

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Chapter 7 Cell Strucutre and Function

Course: College Geometry (MAT 115)

4 Documents
Students shared 4 documents in this course

University: Rowan College of South Jersey

Was this document helpful?
Cell: basic unit of all forms of life
Cell theory: fundamental concept of biology
that states that all living things are composed
of cells; that cells are the basic units of
structure and function in living things; and
that new cells are produced from existing
cells.
Cell membrane: thin, flexible barrier that
surrounds all cells; regulates what enters and
leaves the cell
Nucleus: the center of an atom, which
contains the protons and neutrons; in cells,
structure that contains the cell's genetic
material in the form of DNA.
Eukaryotic: organism whose cells contain a
nucleus
Prokaryote: unicellular organism that lacks
a nucleus
Vocabulary:
Key Questions
All living things are made up of cells.
○
Cells are the basic units of structure and function in living things.
○
New cells are produced from existing cells.
○
The cell theory states: •
What is the cell theory?
Most microscopes use lenses to magnify the image of an object by focusing light or
electrons.
How do microscopes work?
Prokaryotic cells do not separate their genetic material within a nucleus.
In eukaryotic cells, the nucleus separates the genetic material from the rest of the cell.
How are prokaryotic and eukaryotic cells different?
The smallest unit of any organism- the cell.
The Discovery of the Cell
Without the instruments to make them visible, cells remained out of sight and, therefore, out of mind for the most of human history. All of this
changed with a dramatic advance in technology- the invention of the microscope.
Early Microscopes
In 1665, Englishman Robert Hooke used an early compound microscope to look at a nonliving thin slice of cork, a plant material. Under the
microscope, cork seemed to be made of thousands of tiny empty chambers. Hooke called these chambers "cells" because they reminded him of
a monastery's tiny rooms, which were called cells. The term cell is used in biology to this day. Today we know that living cells are not empty
chambers, that in fact they contain a huge array or working parts, each with its own function, (organelle.)
In Holland around the same time, Anton van Leeuwenhoek, used a single lens microscope to observe pond water and other things. To his
amazement, the microscope revealed a fantastic world of tiny living organisms that seemed to be everywhere, in the water he and his
neighbors drank, and even in his own mouth. Leeuwenhoek's illustrations of the organisms he found in the human mouth-- which today we call
bacteria.
Cork under microscope: first "Cells"
Robert Hooke:
Robert Hooke's Microscope
Robert Hooke
Anton van Leeuwenhoek:
Leeuwenhoek's Microscope
7.1 Life is Cellular
Sunday, December 16, 2012
1:07 PM
Chapter 7 Cell Strucutre and Function Page 1

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