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Transcript
Chapter Two Section 1 Cell Structure TYPES OF CELLS Defined by having a nucleus. Defined by having complex organelles. • Plant and animal cells. Defined by NOT having a nucleus • Bacteria cells. Common Cell Features Both prokaryotic and eukaryotic cells contain: • ____________ • A cell membrane (protects cell and allows things in and out of the cell). • Ribosomes (protein making factories). • ______________(water-based substance inside the cell). These are typically the only similarities between the two different types of cells. Eukaryotic cells contain organelles, a word that literally means “little organ”. Organelles have specific functions that they employ throughout the cell. There are approximately a dozen different organelles! What is it? a large, central membrane-bound organelle which contains D.N.A. Where is it found? All eukaryotic cells! (BOTH plant and animal cells have a nucleus). What does it do? Protects the DNA! What is it? A porous membrane that encases the nucleus. These “nuclear pores” allow certain substances to pass into and out of the nucleus. Where is it found? In all eukaryotic cells; BOTH plant and animal. What does it do? The nuclear envelope protects the nucleus. What is it? A structure contained within the nucleus. Where is it found? Inside the nucleus of eukaryotic cells. What does it do? It is responsible for making ribosomes. What is it? Gelatin like mixture that flows inside the cell membrane Where is it found? In all eukaryotic cells; BOTH plant and animal. Also in prokaryotic cells. What does it do? Takes up all the “empty” space. What is it? A selectively permeable protection of the cell. Where is it found? In all eukaryotic cells; BOTH plant and animal. Also in prokaryotic cells. What does it do? Allows certain things to enter and leave the cell. What is it? A tunnel-like network of membranes. Where is it found? Connected to the nucleus and branching out into the cytoplasm of all eukaryotic cells. Endoplasmic Reticulum con’t What does it do? Transfers substances within the cell, as well as many different chemical reactions including protein modification and distribution. ER is like the highway system of the cell! T W O T Y P E S Smooth E.R. (free of ribosomes) Rough E.R. (contains ribosomes) What is it? A membrane-bound organelle, which processes and packages proteins. Where is it found? The cytoplasm of all eukaryotic cells. What does it do? Acts like a post office by packaging proteins in vesicles and delivering them to other parts of the cell. What is it? Ribosomes are cell organelles that consist of RNA and proteins. Where is it found? In all eukaryotic and prokaryotic cells. What does it do? They are responsible for assembling the proteins of the cell. What are they? Vesicles that contain powerful digestive enzymes. Where are they found? In all eukaryotic cells. What do they do? Break down old cell parts and fight off invading ____________. What is it? A unique, double membrane-bound organelle, which contains its own DNA. Where is it found? All eukaryotic cells. What does it do? Generates A.T.P. (cellular energy) Vacuoles differ among plant and animal cells. PLANT CELLS ANIMAL CELLS There is ONE, LARGE central vacuole. The central vacuole of plants stores water and nutrients, and also aids in cellular digestion. There are multiple, small vacuoles. www.cellsalive.com The vacuoles of animal cells do not store water or nutrients, but rather waste as they aid in cellular digestion. What are they? Nine triplets of microtubules. Where are they found? IN ANIMAL CELLS ONLY! What do they do? Assist during nuclear division. What are they? Membrane-bound organelles that contain light-absorbing pigments. Where are they found? ______________cells only! What do they do? Harvest energy from the sun for photosynthesis. What is it? A structure consisting of cellulose that surrounds the cell membrane. Where is it found? Within eukaryotes the cell wall is ONLY found in ________, however all prokaryotes also have a cell wall. What does it do? Protects the cell and maintains homeostasis. Cell Structure Cytoplasm (P&A) Cell Membrane (P&A) Nucleus (P&A) Endoplasmic Reticulum (P&A) Gelatinlike mixture that flows inside the cell membrane Allows materials to move in and out cell Directs all cell activities (the “brain” of the cell) Moves materials around in cell Cell Structure Ribosomes (P&A) Mitochondira (P&A) Chloroplast (P) Makes protein Releases energy stored in food Captures light and stores for energy Cell Wall (P) Protects the plant Vacuole (P&A) Stores water, waste products, food, and other cellular materials Cell Structure Golgi Bodies (P&A) Package and sort cellular substances for export Lyosome (P&A) Breaks down food molecules, cell wastes, and worn-out cell parts. Animal Cell v. Plant Cell Animal Cell Plant Cell Lysosomes Cell Wall Cell Membrane Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Mitochondrion Chloroplast Vacuole Gogli Body The Cell Theory • The Cell Theory arose after hundreds of years of observation, and many scientists. A few key scientists involved in the cell theory are Hooke, Schleiden, Schwann and Virchow. Robert Hooke- The first scientist to describe what he saw as “cells” when viewing samples of cork under the microscope in 1665. The Cell Theory Nearly 200 years later, Matthias Schleiden viewed living plant specimens under the microscope and discovered they were made up of cells. Around the same time as Schleiden, Theodor Schwann viewed nonliving animal parts under a microscope and realized that they, too were made up of cells. The Cell Theory Finally, Rudolf Virchow witnessed cell division under the microscope and learned that all cells arise from preexisting cells. The findings of these scientists, among others, lead to the cell theory, which states: Cell Theory All organisms are made up of one or more cells An organism can be one cell or many cells like most plants and animals The cell is the basic unit of structure and function of life. Even in complex organisms, the cell is the basic unit of structure and function All cells come from preexisting cells. Most cells can divide to form two new, identical cells. Looking at Cells Introduction to the Microscope Looking at Cells Measurement Review! centimeter= 1/100 of a meter (cm) =approximate width of a fingernail millimeter= 1/1000 of a meter (mm) =equivalent to the width of a pencil tip micrometer= 1/1,000,000 of a meter (µm) = about the length of half of one E. Coli nanometer= 1/1,000,000,000 of a meter (nm) about the size of a very large molecule Looking at Cells Cells are measured in micrometers, which is abbreviated as µm. A micrometer is equal to one millionth of a meter. Micrometers are also known as microns. Some cells are only half a micron in diameter, which means you could fit two million cells along the length of a meter stick. They are naked to the human eye! Anton van Leeuwenhoek • A Dutch scientist born in 1632 • He did NOT invent the microscope, but he did improve it. • His new improved microscope was able to see things that no man had ever seen before, i.e., bacteria, yeast, blood cells and many tiny animals swimming about in a drop of water. He called these “animalcules”. Robert Hooke • Robert Hooke, an English scientist who was the first scientist to give cells their name. • When looking at a wine cork under a microscope in 1665, he saw something similar to this: Classroom Microscope The compound light microscope: • The compound microscope has multiple lenses and needs a light source in order to magnify objects. • This microscope is ideal for looking at a wide range of living or preserved specimens, though it can only magnify up to 1,000-2,000x larger. Cells under a compound light microscope. Electron Microscopes An electron microscope is any microscope that uses a beam of electrons to form an image of a specimen. However, they are generally NOT used to view living specimens. The specimen is always dead and preserved. There are three types of electron microscopes: 1) Transmission electron microscope (TEM) 2) Scanning electron microscope (SEM) 3) Reflection electron microscope Transmission Electron Microscope (TEM) • Original electron microscope • Invented in the 1930s • Can magnify an object 750,000x its original size. • Capable of revealing a cell’s detailed structure. • Ideal for use on cells because TEM’s produce highly magnified 3-dimensial images of the cell, as we will see in the virtual microscope! Scanning Tunneling Microscope • Invented in the 1980’s • Can magnify up to 2,000,000x an object’s original size. • Safe for living specimens . • Produces color images. • Used to view atoms and molecules- even cells are too big for the capacity of this amazing instrument! Vocabulary 1. _____________________: a measure of the image clarity. Example) unclear pictures= poor resolution 2. __________________________: making an image look larger than its actual size. This is done using lenses (like a magnifying glass or eyeglasses). 3. SI units: a system of measurement based on powers of 10. A compound microscope uses SI because its eyepiece lens is 10x. Lenses of the Microscope and Total Magnification 4x 100x 40x 10x Objective Lenses (3-4 total) Eyepiece (piece you look through) always has a 10x lens! Total magnification= eyepiece lens x objective lens! The microscope is currently set on the 10x objective lens. What is the total magnification? Convex Lenses -It is very important to note that the eyepiece is a CONVEX lens. -This is the same type of lens that is found in our eyes. The convex lens Inverts an image and makes it backwards. Image Quality When you look at a specimen using a microscope, the quality of the image you see is assessed by the following: •Brightness - How light or dark is the image? •Focus – A measure of the definition of the image. Is the image blurry or well-defined? •Resolution - the smallest distance between two objects at which the objects still appear to be separate from one another; measures the clarity of the image (allows details to be observed). •Contrast– The difference in lighting between adjacent areas of the specimen. Parts of the Light Microscope eyepiece body tube nose piece arm objective lenses stage stage clips diaphragm light source course adjustment fine adjustment base Chapter Two Section 3 Viruses Viruses • A ____________is a strand of hereditary material surrounded by a protein coating. Viruses don’t have a nucleus, other organelles or a cell membrane. • All viruses can do is make copies of themselves, but can’t do that without the help of a _________________. How Viruses Attack • Active Virus • • Causes host cell to make new viruses. This process destroys the host cell Process 1. The virus attaches to a specific host cell 2. The virus’s hereditary material enters the host cell 3. The hereditary material of the virus causes the cell to make viral hereditary material and proteins 4. New viruses form inside of the host cell 5. New viruses are released as the host cell burst open and is destroyed How Viruses Attack • Latent Virus • This means that after the virus enters the cell, its hereditary material can become part of the cell’s hereditary material. It does not immediately make new viruses or destroy the cell. • As the cell multiplies the viral DNA is copied. • Factors either inside or outside your body can activate the virus. Fighting Viruses • Vaccine • Used to prevent disease. Made from weakened virus particles that can’t cause disease anymore. • First Vaccine • Edward Jenner developed 1st vaccine for small pox. Treating and Preventing Viral Diseases • Antibiotics • Used to treat bacterial infections and WILL NOT work against viral infections. • Antiviral drugs can be given to infected patients to help fight a virus. • Improving sanitary conditions will also prevent viral infections (SO WASH YOUR HANDS!) • Quarantining Patients • Controlling animals that spread disease • rabies Gene Therapy • There are some helpful uses to viruses. • Cells with defective genes are given normal hereditary material in place of the defective hereditary material. • This normal material is enclosed in viruses that “infect” the targeted cells. • Using gene therapy, scientists hope to help people with genetic disorders and find a cure to cancer.