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By: ellag (41 month(s) ago)

Aloha, just wondering if I could use a few of your slides for a class presentation. Mahalo, Ella

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Chapter: Cells Table of Contents Section 3: Viruses Section 1: Cell Structure Section 2: Viewing Cells

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A cell is the smallest unit that is capable of performing life functions. All cells have an outer covering called a cell membrane. Inside every cell is a jelly like material called cytoplasm (SI tuh pla zum). Common Cell Traits Cell Structure 1 In the cytoplasm of every cell is hereditary material that controls the life of the cell.

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A nerve cell in your leg could be a meter long. A human egg cell is no bigger than the dot on an i. Comparing Cells Cell Structure 1 A human red blood cell is about one-tenth the size of a human egg cell.

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Comparing Cells Cell Structure 1 A bacterium is even smaller—8,000 of the smallest bacteria can fit inside one of your red blood cells.

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Comparing cells- size and shape of a cell relate to its function Comparing Cells Cell Structure 1

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Scientists have found that cells can be separated into two groups. Cells without membrane-bound structures and nucleus are called prokaryotic (proh KAYR ee yah tihk) cells. Example: Bacteria cell Cell Types Cell Structure 1

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Eukaryotic (yew KAYR ee yah tihk) cells do have a nucleus and have membrane-bound organelles which are tiny organs for the cell. Example: Animal and plant cell. Cell Types Cell Structure 1

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The cells of plants, algae, fungi, and most bacteria are enclosed in a cell wall. Cell walls are tough, rigid outer coverings that protect the cell and give it shape. Cell Organization—Cell Wall Cell Structure 1

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The protective layer around all cells is the cell membrane. It lets things in and out of the cell. If cells have cell walls, the cell membrane is inside of it. Cell Membrane Cell Structure 1 The cell membrane allows food and oxygen into the cell and waste products out of the cell

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Cells are filled with a gelatinlike substance called cytoplasm that is inside the cell membrane. Throughout the cytoplasm is a framework called the cytoskeleton, which helps the cell maintain or change its shape. Cytoplasm Cell Structure 1

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Within the cytoplasm of eukaryotic cells are structures called organelles. Some organelles process energy and others manufacture substances needed by the cell or other cells. They are like tiny organs for the cells Cytoplasm Cell Structure 1 Most organelles are surrounded by membranes. The nucleus is usually the largest organelle in a cell.

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The nucleus directs all cell activities and is separated from the cytoplasm by a membrane. It is the brain of the cell. The nucleus contains the instructions for everything the cell does. It is the control center of the cell. Nucleus Cell Structure 1

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These instructions are found on long, threadlike, hereditary material made of DNA. DNA is the chemical that contains the code for the cell’s structure and activities. Nucleus Cell Structure 1 A structure called a nucleolus also is found in the nucleus.

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These organells help cells do their job. In plant cells, food is made in green organelles in the cytoplasm called chloroplasts (KLOR uh plasts). Chloroplasts contain the green pigment chlorophyll, which gives many leaves and stems their green color. It helps in photosynthesis Energy-Processing Organelles Cell Structure 1

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Chlorophyll captures light energy that is used to make a sugar called glucose. Glucose molecules store the captured light energy as chemical energy. Energy-Processing Organelles Cell Structure 1 Many cells, including animal cells, do not have chloroplasts for making food. They must get food from their environment.

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The energy in food is stored until it is released by the mitochondria. Mitochondria are organelles where energy is released from breaking down food into carbon dioxide and water. It is called the powerhouse of the cell. Energy-Processing Organelles Cell Structure 1

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Cells make their own proteins on small structures called ribosomes. Manufacturing Organelles Cell Structure 1

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Some ribosomes float freely in the cytoplasm; others are attached to the endoplasmic reticulum. Ribosomes receive directions from hereditary material on how, when, and in what order to make specific proteins. Manufacturing Organelles Cell Structure 1

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The endoplasmic reticulum (en duh PLAZ nuhk • rih TIHK yuh lum), or ER, extends from the nucleus to the cell membrane. Processing, Transporting, and Storing Organelles Cell Structure 1 It is a series of folded rough or smooth membranes in which materials can be processed and moved around inside of the cell.

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The endoplasmic reticulum may be “rough” or “smooth.” ER that has no attached ribosomes is called smooth endoplasmic reticulum. Rough ER moves proteins around inside the cell. Processing, Transporting, and Storing Organelles Cell Structure 1

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After proteins are made in a cell, they are transferred to another type of cell organelle called the Golgi (GAWL jee) bodies. The Golgi bodies package materials and move them out of the cell or to other parts of the cell. Processing, Transporting, and Storing Organelles Cell Structure 1

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Processing, Transporting, and Storing Organelles Cell Structure 1 Cells have membrane-bound spaces called vacuoles for the temporary storage of materials. A vacuole can store food and water, waste products, and other cellular materials. They can be really big in plant cells.

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Recycling Organelles Cell Structure 1 Organelles called lysosomes (LI suh sohmz) contain digestive chemicals that help break down food molecules, cell wastes, and worn-out cell parts.

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From Cell to Organism Cell Structure 1 Cell – smallest unit of organization and life A tissue is a group of similar cells that work together to do one job. Tissues are organized into organs.

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From Cell to Organism Cell Structure 1 An organ is a structure made up of two or more different types of tissues that work together. Your heart is an organ made up of cardiac muscle tissue, nerve tissue, and blood tissues.

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From Cell to Organism Cell Structure 1

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Question 1 Which of these cells is a bacteria cell? Section Check 1

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Answer Prokaryotic cells are only found in one-celled organisms, such as bacteria. Prokaryotic cells are cells without membrane-bound structures. Section Check 1

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Question 2 Answer Which part of the cell protects the cell and gives it shape? Cell walls are tough, rigid outer coverings that protect the cell and give it shape. The cells of plants, algae, fungi, and most bacteria are enclosed in a cell wall. Section Check 1

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Question 3 Answer In what part of the cell is the cytoskeleton found? Cytoplasm is the gelatinlike substance within the cell. The cytoskeleton is found throughout the cytoplasm. Section Check 1

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Magnifying Cells To see most cells, you need to use a microscope. A microscope has one or more lenses that enlarge the image of an object as though you are walking closer to it. Viewing Cells 2

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Modern Microscopes Depending on how many lenses a microscope contains, it is called simple or compound. A simple microscope is similar to a magnifying lens. Viewing Cells 2 It has only one lens. A microscope’s lens makes an enlarged image of an object and directs light toward your eye. The change in apparent size produced by a microscope is called magnification.

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Modern Microscopes The compound light microscope has two sets of lenses—eyepiece lenses and objective lenses. The eyepiece lenses are mounted in one or two tubelike structures. Viewing Cells 2 Compound light microscopes usually have two to four movable objective lenses.

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Magnification The powers of the eyepiece and objective lenses determine the total magnifications of a microscope. If the eyepiece lens has a power of 10× and the objective lens has a power of 43×, then the total magnification is 430× (10× times 43×). Viewing Cells 2

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Electron Microscopes Things that are too small to be seen with other microscopes can be viewed with an electron microscope. Instead of using lenses to direct beams of light, an electron microscope used a magnetic field in a vacuum to direct beams of electrons. Viewing Cells 2

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Electron Microscopes Viewing Cells 2 Transmission electron microscopes (TEM) produce a two-dimensional image of a thinly-sliced specimen. Scanning tunneling microscopes (STM) are able to show the arrangement of atoms on the surface of a molecule.

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Cell Theory Cells weren’t discovered until the microscope was improved. In 1665, Robert Hooke cut a thin slice of cork and looked at it under his microscope. Viewing Cells 2 To Hooke, the cork seemed to be made up of empty little boxes, which he named cells.

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Cell Theory In the 1830s, Matthias Schleiden used a microscope to study plants and concluded that all plants are made of cells. Theodor Schwann, after observing different animal cells, concluded that all animals are made up of cells. Viewing Cells 2 Eventually, they combined their ideas and became convinced that all living things are made of cells.

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Cell Theory Several years later, Rudolph Virchow hypothesized that cells divide to form new cells. His observations and conclusions and those of others are summarized in the cell theory. Viewing Cells 2

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2 Section Check Question 1 Who developed a microscope using a tiny glass bead for a lens? A. Antonie van Leeuwenhoek B. Edward Jenner C. Matthias Schleiden D. Theodor Schwann

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2 Section Check Answer The answer is A. His microscope could magnify up to 270 times.

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2 Section Check Question 2 How many lenses does a simple microscope have? A. 0 B. 1 C. 2 D. 4

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2 Section Check Answer The answer is B. A simple microscope is similar to a magnifying glass.

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2 Section Check Question 3 The conclusions listed in this table are known as the _______.

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2 Section Check A. Cell Theory B. Koch’s Rules C. Law of Independent Assortment D. Principles of Natural Selection

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2 Section Check Answer The answer is A. The research and conclusions of Robert Hooke, Matthias Schleiden, Theodor Schwann, and Rudolf Virchow contributed to the development of the cell theory.

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What are viruses? A virus is a strand of hereditary material surrounded by a protein coating. Viruses don’t have a nucleus, other organelles, or a cell membrane. Viruses have a variety of shapes. Viruses 3

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How do viruses multiply? All viruses can do is make copies of themselves. Crystallized forms of some viruses can be stored for years. Viruses 3 They can’t do that without the help of a living cell called a host cell.

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How do viruses multiply? Viruses 3 Then, if they enter an organism, they can multiply quickly. Once a virus is inside of a host cell, the virus can act in two ways. It can either be active or it can become latent, which is an inactive stage

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Active Viruses Viruses 3 When a virus enters a cell and is active, it causes the host cell to make new viruses. This process destroys the host cell. Click image to view movie.

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Latent Viruses Viruses 3 Some viruses can be latent, which means that after it enters a cell, its hereditary material can become part of the cell’s. It does not immediately make new viruses or destroy the cell. As the host cell reproduces, the viral DNA is copied. Click image to view movie.

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Latent Viruses Viruses 3 A virus can be latent for many years. Then, at any time, certain conditions can activate the virus. If you have had a cold sore on your lip, a latent virus in your body has become active.

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Vaccines have been made to prevent many diseases, including measles, mumps, smallpox, chicken pox, polio, and rabies. Fighting Viruses Viruses 3 Vaccines are used to prevent disease. A vaccine is made from weakened virus particles that can’t cause disease anymore.

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Jenner noticed that people who got a disease called cowpox didn’t get smallpox. The First Vaccine Viruses 3 Edward Jenner is credited with developing the first vaccine in 1796. He developed a vaccine for smallpox, a disease that was still feared in the early twentieth century.

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Jenner didn’t know he was fighting a virus. The First Vaccine Viruses 3 He prepared a vaccine from the sores of people who had cowpox. When injected into healthy people, the cowpox vaccine protected them from smallpox. At that time, no one understood what caused disease or how the body fought disease.

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Interferons are proteins that are produced rapidly by virus-infected cells and move to noninfected cells in the host. Treating Viral Diseases Viruses 3 Antibiotics treat bacterial infections but are not effective against viral diseases. One way your body can stop viral infections is by making interferons.

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A few drugs show some effectiveness against viruses but some have limited use because of their adverse side effects. Treating Viral Diseases Viruses 3 Interferons cause the noninfected cells to produce protective substances. Antiviral drugs can be given to infected patients to help fight a virus.

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Question 1 Answer A _______ is a nonliving strand of hereditary material surround by a protein coating. The answer is virus. Viruses do not have a nucleus or other organelles. Section Check 3

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3 Section Check Question 2 Which happens to the host cell after the active virus is duplicated? A. It divides through cell division B. It is destroyed C. It functions normally It continues to produce more and more new viruses

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3 Section Check Answer The answer is B. Latent, or inactive, viruses do not destroy the host cell until they become active.

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3 Section Check Question 3 Who developed the first vaccine? A. Edward Jenner B. Gregor Mendel C. Reginald C. Punnett D. Theodor Schwann

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3 Section Check Answer The answer is A. A vaccine is made from weakened virus particles that can’t cause disease anymore.

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To advance to the next item or next page click on any of the following keys: mouse, space bar, enter, down or forward arrow. Click on this icon to return to the table of contents Click on this icon to return to the previous slide Click on this icon to move to the next slide Click on this icon to open the resources file. Help Click on this icon to go to the end of the presentation.

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End of Chapter Summary File