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Transcript
EARLY MICROSCOPES • Zacharias Janssen - made 1st compound microscope • a Dutch maker of reading glasses (late 1500’s) Leeuwenhoek • made a simple microscope (mid 1600’s) • magnified 270X • Early microscope lenses made images larger but the image was not clear Leeuwenhoek's microscope A) a screw for adjusting the height of the object being examined B) a metal plate serving as the body C) a skewer to impale the object and rotate it D) the lens itself, which was spherical MODERN MICROSCOPES • A microscope is simple or compound depending on how many lenses it contains • A lens makes an enlarged image & directs light towards you eye • A simple microscope has one lens • Similar to a magnifying glass • Magnification is the change in apparent size produced by a microscope COMPOUND MICROSCOPE • A compound microscope has multiple lenses – (eyepiece & objective lenses) Microscope • Magnification increases the size of an object. • As the magnification increases your field of view decreases. • Resolution increases the ability to see details of the specimen TOTAL MAGNIFICATION • Powers of the eyepiece (10X) multiplied by objective lenses determine total magnification. STEREOMICROSCOPE • creates a 3D image ELECTRON MICROSCOPES • More powerful; some can magnify up to 1,000,000X • Use a magnetic field in a vacuum to bend beams of electrons • Images must be photographed or produced electronically Scanning Electron Microscope (SEM) Electron microscope image of a spider produces realistic 3D image only the surface of specimen can be observed Electron microscope image of a fly foot SEM Image SEM Image SEM Images Dust Mite Pollen SEM Sickle Cell Virus Transmission Electron Microscope (TEM) • produces 2D image of thinly sliced specimen • detailed cell parts (only inside a cell) can be observed TEM Golgi Apparatus and vesicles Scanning Tunneling Microscope (STM) • able to show arrangement of atoms Scanning Tunneling Microscope(STM) • Device for studying and imaging individual atoms on the surfaces of materials. The instrument was invented in the early 1980s by Gerd Binnig and Heinrich Rohrer, who were awarded the 1986 Nobel prize in physics for their work. • The underlying principle of the STM is the tunneling of electrons between the sharp tip of a probe and the surface of the sample under study. The flow of electrons is extremely sensitive to the distance between the tip and the sample. As the tip is swept over the surface the height of the tip is continually adjusted so as to keep the flow of electrons constant. A map of the "bumps" on the surface is then obtained by accurately recording the height fluctuations of the tip. • The STM was used in 2004 to measure the charges of individual atoms, and in 2010 researchers used a modified STM to observe the magnetism, or spin, of atoms on the nanosecond timescale. CELL THEORY • A theory resulting from many scientists’ observations & conclusions CELL THEORY 1. The basic unit of life is the cell. (Hooke) • In 1665, an English scientist named Robert Hooke made an improved microscope and viewed thin slices of cork viewing plant cell walls • Hooke named what he saw "cells" CELL THEORY 2. All living things are made of 1 or more cells. • Matthias Schleiden (botanist studying plants) • Theodore Schwann (zoologist studying animals) stated that all living things were made of cells Schwann Schleiden CELL THEORY 3. All cells divide & come from old cells. (Virchow) Virchow Cell Theory • Hooke and Leeuwenhooke recorded all that they saw. • Schleiden, Swann, & Virchow further studied cells and proposed The Cell Theory. Page 55. Cell Theory 1. All living organisms are composed of one or more cells. 2. Cells are the basic structure and organization of all living organisms. 3. Cells come from previously existing cells, with cells passing copies of their genetic material on to their daughter cells. Cell Size • A cells size is limited by the ratio of their outer surface and their inner volume. • As cells increase their volume (the stuff inside) Their out membrane stretches (like blowing up a balloon). • Too much volume – Can burst the cell. – Reduce transport across the outer membrane. Cell Size Cell Shape • Cells can vary in shape depending on their function • All cells contain organelles which are similar in function to human internal organs. –The cell membrane surrounds and protects the cell. Cell Shape Two Types of Cells • Eukaryotic – Membrane bound nucleus that houses all of the cells genetic material – Many membrane bound organelles (p.58). • Prokaryotic – No Membrane bound nucleus - the cells genetic material floats randomly in the cell – Many organelles NOT bound by a membrane – Have a cell wall surrounding the cell membrane Eukaryotic - Algae Algae cell Eukaryotic-Red Algae Eukaryotic - Protists Ameoba paramecium Eukaryotic –protist -algae Fungi Fungi flower Fungi cell Eukaryotic - Yeast Internal Organization Cell membrane Cytoplasm Prokaryotic Cell Cell membrane Cytoplasm Eukaryotic Cell Nucleus Organelles Compare and Contrast Prokaryotes Cell membrane Contain DNA Ribosome Cytoplasm Eukaryotes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Prokaryotic Examples ONLY Bacteria Prokaryotes • Cell wall in a bacterial cell is typical made from a carbohydrate-protein complex called peptoglycan or similar substance. • Cytoplasm and cytoskeleton • Do not contain a nucleus DNA is circular and DNA area is called nucleoid • Some bacteria contain plasmids DNA that are independent of the main DNA. Bacteria can exchange these. Ex. Plasmid may express allow a bacteria to express an ability like make a sugar outer coating. • Have ribosomes • Cilia and flagella for movement. Eukaryotic Example Venn Diagrams Compare and Contrast Animal Cells Centrioles Plant Cells Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Wall Chloroplasts • • • • • Organelles Cell membrane Nucleus Mitochondrion Ribosome Endoplasmic reticulum • Golgi apparatus • Lysosome/perox isomes • Microfilament & microtubules • Cilia and flagella • Cell wall – Plant cell • Vacuole – plant cells • Chloroplast – plant cells Check Point 1.What is the importance of a surface area to volume ratio? 2. Compare the structure of a eukaryotic cell with a prokaryotic cell? 3.When Hooke first used the word cell, did the intend to have it apply to living material? Explain. 4. Name two structures that all cells have. Animal Cell Cell membrane Fluid Mosaic Model Proposed in 1972 by Singer • Selectively permeable & pliable membrane • Membrane lipids – Phospholipids – polar head and nonpolar tails. The polar head are hydrophilic and the non-polar tails are hydrophobic – Steroid (cholesterol) is located between the tails of the phospholipids Cell Membrane • Proteins embedded in cell membrane –Peripheral – external peripheral proteins have a carbohydrate attached –Integral – in between the phospholipids; can form channels to allow transport in and out of the cell Cell Membrane • Boundary of the cell • Made of a phospholipid bilayer Cell Membrane Cell Membrane Nucleus • Is surrounded by the nuclear matrix which is a stiff membrane • There is an inner membrane called a nuclear envelope • Chromatin (a combination of DNA and protein) is inside the nucleus. The chromatin coils and becomes chromosomes when the cell is ready to divide. Nucleus • Nucleus stores genetic information • Is where RNA is copied from DNA • Nuclear pores allow RNA to travel out of the nucleus. • Contains the nucleolus where ribosome's are made. Nucleus • Control center of the cell • Contains DNA • Surrounded by a double membrane • Usually the easiest organelle to see under a microscope • Usually one per cell Ribosome • • • • • Most abundant in the cell No outer membrane Is made up of a protein and RNA Are made in the nucleus Can be free floating (remain in cell)or attached to endoplasmic reticulum (for export). • Make proteins • Found in all cells Ribosome • Site of protein synthesis • Found attached to rough ER or floating free in cytosol • Produced in a part of the nucleus called the nucleolus That looks familiar…what is a polypeptide? Endoplasmic reticulum (ER) • Highway of tubes and sacs by which molecules move around the cell • Has a membrane • Two types – Rough – is covered in ribosomes is found in cells that make many proteins – Smooth – helps make steroids, regulates calcium in muscles, and breaks down toxins in the liver Endoplasmic Reticulum • A.k.a. “ER” • Connected to nuclear membrane • Highway of the cell • Rough ER: studded with ribosomes; it makes proteins • Smooth ER: no ribosomes; it makes lipids Golgi Apparatus • Processing, packaging and secretion center • Is a system of tubes and sacs • Enzymes that are in the Golgi attach carbohydrates and lipids to the proteins. • Make cell membrane components or the cell. • Packages for distribution lysosomes. Golgi Apparatus • Looks like a stack of plates • Stores, modifies and packages proteins • Molecules transported to and from the Golgi by means of vesicles Lysosomes • Spherical organelles that contain hydrolytic enzymes which digest proteins, nucleic acids, lipids and carbohydrates. • This allows lysosomes to recycle cell parts. • Lysosmoes remain in the cell. Lysosomes • Garbage disposal of the cell • Contain digestive enzymes that break down wastes Which organelles do lysosomes work with? lysosomes • Pump enough H ion to maintain a pH of 5. • Contain about 40 different enzymes that breakdown macromolecules. Peroxisomes • Globular organelles found in almost all eukaryotes but many different types place where oxidation reactions take place. • ex. Breaks down Hydrogen peroxide. • ex. Brake down of ethanol • ex. Breakdown of fatty acids Mitochondria • Change organic compounds to energy called adenosine triphosphate (ATP) • Has two membranes – Inner membrane called cristae which increases the surface area so more compounds can be converted to ATP. – Outer membrane protects and allows transport. • Has its own DNA and can reproduce to make more mitochondria Endosymbiotic theory • Notion that several key organelles of eukaryotes originated as symbiosis between separate single-celled organisms. • Mainly mitochondria and chloroplasts possibly other organelles. Evidence • DNA evidence suggest mitochondria developed from proteo-bacteria in particular Rickettsiales or a close relative and chloroplast from cyanobacteria. • Mitochondria and chloroplast have their own DNA separate form the DNA found in the nucleus. • Their DNA is circular like bacterial DNA and sequencing reveals similarities in with the above mention bacteria. Mitochondria • “Powerhouse of the cell” • Cellular respiration occurs here to release energy for the cell to use • Bound by a double membrane • Has its own strand of DNA (circular) • Inherit from mom only Mitochondria Cell Wall • Cell wall found in fungi, algae, bacteria, archea, and plants. Animal cells, and protists do not • Rigid outer wall of a plant cell • Cell growth is limited by the size of the cell wall Cell Wall • Plants cell wall is generally composed of cellulose • Lignin and cellulose combine to form the bark what we refer to as wood. • Fungi cell wall is mainly chitin • Bacteria is mainly peptoglycan Cell Wall • Found in plant and bacterial cells • Rigid, protective barrier • Located outside of the cell membrane • Made of cellulose (fiber) Cell Wall Plant Cell Wall Cell Wall Vacuoles • Common in plant cells • Store enzymes and metabolic waste • May be extremely large Vacuoles • Large central vacuole usually in plant cells • Many smaller vacuoles in animal cells • Storage container for water, food, enzymes, wastes, pigments, etc. What type of microscope may have been used to take this picture? Chloroplasts • Are surrounded by two membranes • Contain DNA • May store starches and fats or contain pigments used to absorb light for photosynthesis • A chloroplast is a plastid – Contains thylakoids which convert lights energy into usable energy for the plant Chloroplast • Found only in plant cells • Contains the green pigment chlorophyll • Site of food (glucose) production • Bound by a double membrane Chloroplast Endosymbiotic Theory • Several key organelles of eukaryotes originated as symbioses between separate single-celled organisms. According to this theory, mitochondria and plastids ( chloroplasts), and possibly other organelles, represent formerly free-living bacteria that were taken inside another cell as an endosymbiont. • Molecular and biochemical evidence suggest that the mitochondrion developed from proteobacteria (in particular, Rickettsiales or close relatives) and the chloroplast from cyanobacteria. • This theory is a partial explanation of the evolution of eukaryotic cells from prokaryotic cells. Cytoplasm and Cytoskeleton • Cytoplasm is a semi fluid material. • Organelles do not float freely but are supported by a cytoskeleton. Cytoskeleton • Is made up of: • Microtubules that look like tubes. But are long hollow protein cylinders. Provide a rigid skeleton and assist in moving substances. • Microfilaments look like webs these thin protein threads give the cell shape and allow for movement. • Both microtubules and microfilaments slide past one another allowing organelles to move. Cytoskeleton • Acts as skeleton and muscle • Provides shape and structure • Helps move organelles around the cell • Made of three types of filaments Cytoskeleton Cytoskeleton Centriole • Aids in cell division • Usually found only in animal cells • Made of microtubules Where else have we talked about microtubules? Levels of Organization Quick Review • Which organelle is the control center of the cell? Nucleus • Which organelle holds the cell together? Cell membrane • Which organelles are not found in animal cells? Cell wall, central vacuole, chloroplasts • Which organelle helps plant cells make food? Chloroplasts • What does E.R. stand for? Endoplasmic reticulum Overview: How a protein is made…. • DNA unwinds and unzips, mRNA transcribes the DNA code( chemical language) to RNA code. • mRNA goes to the ribosome and the ribosome (rRNA) translates the chemical code into a protein one a amino acid at a time. • If the protein is made on a ribosome attached to the endoplasmic reticulum (RER) it will be folded and prepared for transport via vesicle. • Then the protein goes to the Golgi Apparatus where it acquires carbohydrate tails for directions(like an address) and is shipped out of the cell (export) in a vesicle. • Remember the cells use a chemical language of mostly proteins. Carbohydrates, lipids, and nucleic acids are also used in communication. Protein synthesis animation • https://youtu.be/D3fOXt4MrOM