Post on 18-Dec-2015
Chapter: Cells
Table of ContentsTable of Contents
Section 3: Viruses
Section 1: Cell Structure
Section 2: Viewing Cells
• Cell - smallest unit that is capable of performing life functions.
• Cell Membrane - outer covering
• Cytoplasm - gelatinlike material inside cell
Common Cell Traits
Cell StructureCell Structure
11
• Nerve cell - could be a meter long.
• Human egg cell – the size of dot on an i
Comparing Cells
Cell StructureCell Structure
11
• Human red blood cell - 1/10 size of a human egg cell.
• Bacterium - 8,000 bacteria fit inside one red blood
• Prokaryotic - without membrane-bound structures
2 Cell Types
Cell StructureCell Structure
11
• Eukaryotic - with membrane-bound structures
• Cell walls
• tough, rigid outer coverings
• protect the cell and give it shape.
• found in plants, fungi, and bacteria
• made of cellulose
Cell Organization—Cell Wall
Cell StructureCell Structure
11
• protective layer around all cells
• found inside of cell wall
Cell Membrane
Cell StructureCell Structure
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• regulates interactions between the cell and environment.
• gelatinlike substance inside cell
• contains cytoskeleton
• made of tubes and fibers of protein
Cytoplasm
Cell StructureCell Structure
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• Organelles – membrane bound structures
• found in Eukaryotic cells
• directs all cell activities
• largest organelle
• contains DNA – strands of hereditary information
Nucleus
Cell StructureCell Structure
11
• In plant cells, food is made in green organelles in the cytoplasm called Chloroplasts
• found in plant cells
• Chlorophyll – green pigment
• make food (glucose)
Energy-Processing Organelles
Cell StructureCell Structure
11
• Mitochondria - organelles that break down glucose to release energy
Energy-Processing Organelles
Cell StructureCell Structure
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• Ribosomes – make proteins
• found in cytoplasm and on endoplasmic reticulum
Manufacturing Organelles
Cell StructureCell Structure
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• Endoplasmic reticulum (ER)
Processing, Transporting, and Storing Organelles
Cell StructureCell Structure
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• a series of folded membranes
• process and move materials inside cell
• Smooth ER – NO ribosomes
• Rough ER - ribosomes
• Golgi bodies sort proteins and other cellular substances
• package them into membrane-bound transport molecules called vesicles
• Vacuole – large storage organelle
Processing, Transporting, and Storing Organelles
Cell StructureCell Structure
11
Recycling Organelles
Cell StructureCell Structure
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• Lysosomes - contain digestive chemicals that break down molecules
From Cell to Organism
Cell StructureCell Structure
11
• Tissue - a group of similar cells that work together to do one job.
• Organ - made up of two or more types of tissues
From Cell to Organism
Cell StructureCell Structure
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Click box to view movie.
• A group of organs working together to perform a certainfunction is an organ system. Your heart, arteries, veins, and capillaries make up your cardiovascular system.
Question 1
Which of these cells is found in a bacterium?
Section CheckSection Check
11
Answer
Prokaryotic cells are only found in one-celled organisms, such as bacteria. Prokaryotic cells are cells without membrane-bound structures.
Section CheckSection Check
11
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 CheckSection Check
11
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 CheckSection Check
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Magnifying Cells
Viewing CellsViewing Cells
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• Mid 1600s - Antonie van Leeuwenhoek, a Dutch fabric merchant, made a simple microscope with a tiny glass bead for a lens.
• Could magnify up to 270 times.
Modern Microscopes• Simple Microscope – 1 lens
• Compound Microscope – Uses 2 lenses at once
• Eyepiece and Objective lens
Viewing CellsViewing Cells
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• Magnification•Eyepiece x Objective = Total Magnification
Electron Microscopes
• Scanning electron microscopes (SEM) produce a realistic, three-dimensional image.
• Can only observe surface of sample
Viewing CellsViewing Cells
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• Uses a magnetic field in a vacuum to direct beams of electrons
Electron Microscopes
Viewing CellsViewing Cells
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• 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.
Cell Theory
• Robert Hooke (1665) cut a thin slice of cork and looked at it under his microscope – looked like “cells”
Viewing CellsViewing Cells
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• Schleiden & Schwann (1830’s) – all living things are made of cells
• Virchow - cells divide to form new cells.
Cell Theory
Viewing CellsViewing Cells
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22Section CheckSection Check
Question 1Who developed a microscope using a tiny glass bead for a lens?
A. Antonie van LeeuwenhoekB. Edward JennerC. Matthias SchleidenD. Theodor Schwann
22Section CheckSection Check
Answer
The answer is A. His microscope could magnify up to 270 times.
22Section CheckSection Check
Question 2How many lenses does a simple microscope have?
A. 0B. 1C. 2D. 4
22Section CheckSection Check
AnswerThe answer is B. A simple microscope is similar to a magnifying glass.
22Section CheckSection Check
Question 3The conclusions listed in this table are known as the _______.
22Section CheckSection Check
A. Cell TheoryB. Koch’s RulesC. Law of Independent Assortment D. Principles of Natural Selection
22Section CheckSection Check
AnswerThe 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.
What are viruses?
• Virus - strand of hereditary material surrounded by a protein coating
VirusesViruses
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• make copies of themselves.
• Host cell – cell infected by a virus
• It can either be active or it can become latent, which is an inactive stage
Active Viruses
VirusesViruses
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• Causes the host cell to make new viruses.
Click image to view movie.
Latent Viruses
VirusesViruses
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• It does not immediately make new viruses or destroy the cell.
Click image to view movie.
How do viruses affect organisms?
VirusesViruses
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• The virus and the place where it attaches must fit together exactly.
• Because of this, most viruses attack only one kind of host cell.
• Vaccines have been made to prevent many diseases, including measles, mumps, smallpox, chicken pox, polio, and rabies.
Fighting Viruses
VirusesViruses
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• Vaccine - weakened virus particles that can’t cause disease anymore.
The First Vaccine
VirusesViruses
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• Edward Jenner - first vaccine in 1796 for smallpox
• Interferons
• proteins created by infected cells
• cause non-infected cells to produce protective substances
Research with Viruses
VirusesViruses
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• Gene therapy substitutes normal hereditary material for a cell’s defective hereditary material.
• The new hereditary material replaces the defective hereditary material.
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 CheckSection Check
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33Section CheckSection Check
Question 2
Which happens to the host cell after the active virus is duplicated?
A. It divides through cell divisionB. It is destroyedC. It functions normallyD. It continues to produce more and more new viruses
33Section CheckSection Check
Answer
The answer is B. Latent, or inactive, viruses do not destroy the host cell until they become active.
33Section CheckSection Check
Question 3Who developed the first vaccine?
A. Edward JennerB. Gregor MendelC. Reginald C. PunnettD. Theodor Schwann
33Section CheckSection Check
AnswerThe answer is A. A vaccine is made from weakened virus particles that can’t cause disease anymore.
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