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Levels of Organization in Biology Atom Organism Molecule Population Cell Tissue Community Organ Ecosystem ECOLOGY System Biosphere Characteristics of Life 1) Cellular Organization 2) Uses Energy—metabolism (nutrition, transport, respiration, excretion, synthesis) 3) Reproduction 4) Requires Water 5) Respond to the Environment 6) Uses DNA as genetic material 7) Development 8) Evolves Systems • All levels of life have systems of related parts that interact to form a whole. • Have inputs and outputs • Have boundaries Examples of Systems Systems in Biology • Systems can be as small as atoms and molecules to as big as the universe. – Systems have boundaries • E.g. Human skin that surrounds and holds together our internal organs. – Systems have inputs and outputs • matter and energy coming into and of the system boundaries Use the following format for all your lab write ups! 1) Start with a problem statement: • Question based on observation that will be answered in the experiment. You write it in the form of a question “What is the effect of MV on RV?” Ex: Does air contain a life force that causes spontaneous generation or are there other organisms in the air that cannot be seen? 2) Formulate a Hypothesis: • If (manipulated variable)… then (responding variable)… because (relevant explanation). OR • IF (the manipulated variable) IS (describe how you change it), THEN (the responding variable) WILL (describe the effect) BECAUSE … (give a reason for your prediction). He predicted that… Microorganisms carried in the air caused growth of organisms Ex: If a sterilized broth is exposed to air through a swan neck flask, then it will remain free of microorganisms because swan neck will capture any microorganisms that are carried in the air. 3) Identify the variables: • Manipulated: The variable that is changed • Responding: The variable that is measured due to the change Ex: Manipulated: exposure to air Responding: growth of organisms in broth Control (fixed) variables: variables that do not change • At least three CONTROLLED VARIABLES are required, but more may be necessary. The controlled variables you list must be relevant to your investigation. You need to control for all variables that may reasonably affect the outcome of the investigation. Materials used and measurement techniques are NOT controlled variables (they are validity measures). While materials and techniques must be consistent, a true variable is something that could directly influence the responding variable, not just how it is measured. Ex: Temperature at which flasks are stored Time that flasks are allowed to sit Amount of light that flasks are exposed to 4) Identify the Groups: NEW!! • Experimental group- set-up that has the MV • Control group- set-up with no MV **Needs to be included in the procedure Experimental group: sterilized broth in broken flask, sterilized broth in swan neck flask Control group: sterilized broth in sealed swan neck flask. 7) Data Collection: • Record data accurately and neatly • Includes both qualitative and quantitative • Data table must include appropriate units, headings and DESCRIPTIVE title • Averages included when trails are indicated • See sample data table Descriptive title Responding Variable (+ unit of measurement): Manipulated Variable (+ unit of measurement): Trials Levels of MV #1 #2 #3 Average of Trials This table can be made using MS Word, MS Excel or by hand. Data Tables drawn by hand: •Use a ruler. •Neat and legible. •Make it big enough that I can read it! 8) Data Analysis: •Process data in a meaningful way •Look for patterns and trends •Graph and or mathematical calculations Graph: See example….. •Variables listed with units of measurement •Even increments on both X and Y axis •Ruler used whenever hand drawn for all straight lines TITLE Describes what you are studying Y-AXIS Responding Variable & Unit of Measurement NEATNESS •Ruler is used for lines on the graph •Ruler is used for the X and Y axis lines •Legible handwriting X-AXIS Manipulated Variable & Unit of Measurement KEY Identifies different sets of data found in your graph (should be colorcoded) 9) Develop Conclusions: 4 parts •State whether your hypothesis is “supported” or “not supported” •Evidence that your hypothesis is supported or not supported…. Use concrete data. Use range of data when available •Errors/improvements (realistic) •Modifications to the procedure Reminders: •NO ABBREVIATIONS •Include all the parts indicated in the directions •Metric, metric, metric…… Review of Microscopy or Turret Magnification: Ocular (Eyepiece): 10X or Turret Objectives: • • • • Low Power: 4X Medium Power: 10X High Power: 40X Highest Power: 100X Total Magnification: Total Magnification =Ocular X Objective Low Power: 10 X 4 = 40X total mag Medium Power: 10 X 10 = 100X total mag High Power: 10 X 40 = 400X total mag Highest Power: 10 X 100 = 1000X total mag DO NOT ADD!!!! or Turret Lighting the FOV: • The lower the power, the lighter the FOV (easier to see image). • The higher the power, the darker the FOV (harder to see image). – DIAPHRAGM (adjusts the amount of light): Disc underneath the stage that contains holes of different sizes. Dial to a larger hole to let in more light. or Turret Diaphragm Field of View (FOV): Field of View (FOV): • The lower the power, the more FOV you see. (More area is magnified less) • The higher the power, the less FOV you see. (Less area is magnified more) 馠Ї 10x 15X 20X 30X 40X Lighting the FOV: • The lower the power, the lighter the FOV (easier to see image). • The higher the power, the darker the FOV (harder to see image). – DIAPHRAGM (adjusts the amount of light): Disc underneath the stage that contains holes of different sizes. Dial to a larger hole to let in 儐Џ more light. or Turret Diaphragm How to make a wet mount slide preparation 1. 2. 3. 4. 5. Take out a clear, clean slide. Place 2 drops of water on the middle of the slide. Carefully place specimen in the middle of water. Gently lower cover slip onto water drops. Repeat if the following happens… A. B. 嬰Џ Water seeps out sides of cover slips Wick away extra water seeping out by placing a piece of paper towel right next to cover slip. Hold there until all the water is gone from outside of cover slip. Air pockets under cover slip Redo. Modern Microscopes • Some of the light microscopes here are capable of 1000x magnification. – That is about the limit of a light microscope’s magnification without losing clarity (called Resolving Power). • Due to the width of visible light’s wavelength 쬐Ј • The electron microscope was introduced in the 1950s and uses the wavelength of electrons to increase the resolving power by 100x. – Approx. 100,000x magnification!! – Cell Biology advanced rapidly as cellular organelles were clearly seen for the first time. A few limitations of electron microscopes • Specimen must be placed in a vacuum and is typically coated with a conductive metal like gold. Consequently you can’t look at living specimens under electron microscopes. •All images produced are black and white, so you can’t distinguish colors. Pictures are usually colored in digitally later. Ѝ It all started with an invention…. • The first microscope – Sacharias Jansen, 1595, Middleburg, Holland – It launched great leaps in Astronomy and Biology. – Some of the first great observations with it were made by6 傠Њ Robert Hooke (1635-1703) – Designed microscopes – Discovered and documented the first “cells” in 1665 • Named them after the cells in which a monk sleeps. From: http://www.ucmp.berkeley.edu/history/hooke.html Antony van Leeuwenhoek (1632-1723) A tradesman from Holland who became fascinated with Hooke’s book Discovered bacteria, protists, sperm cells, blood cells, nematodes, etc. Became an expert lens grinder and made over 500 simple microscopes Acute eyesight and lens grinding skill let him build microscopes that were capable of 200X magnification 벀Б Cell Theory 1838 Mattias Schleiden stated that all plant tissues consisted of cells 1839 Theodore Schwann stated that all animal tissues consisted of cells Each conjectured that there was a nucleus 1858 Rudolf Virchow combined the two ideas and added that all cells come from pre-existing cells, formulating the Cell Theory 섐Б Rudolf Virchow Cell Theory • All living things are composed of one or more cells • In organisms, cells are the basic units of structure and function. • All cells are produced only from existing cells. А 1858 Prokaryotic vs Eukaryotic Cells 셠Б Prokaryotic Cells (Bacteria) •Prokaryotic Cells – primitive, ‘before kernal’ - NO NUCLEUS – Lack internal membranes (no “membrane-bound” organelles) А – Genetic material: single, circular DNA molecule suspended in the cytoplasm •Ex. Bacteria (such as Anthrax or E. coli) –Microscopic, single-celled organisms Unicellular (one) vs. Multicellular (many) Unicellular: Single-Celled • Most common forms of life on Earth. • Carry out all functions of Life. – Bacteria – Amoeba – Paramecium Unicellular (one) vs. Multicellular (many) Multicellular • Larger organisms. • Different cells have specialized functions, together making a complete organism. – Human – Spider – Jellyfish • Visit a “Tour of the Cell” at: video Cell Membrane: “Security Gate” • Surrounds the cell • Controls movement of materials into and out of cell 숀Б Nucleus: – Controls the functions of the cell (the brain) – Includes the following: • Nuclear Envelope (Membrane): Controls movement into and А out of the nucleus • Nuclear Pore: holes where movement takes place Nucleus: • Nucleolus: Dark area inside nucleus, believed to be for making RNA and ribosomes • Chromatin: Genetic Material (DNA) which is organized into structures called chromosomes during cell division. 쉐Б Cytoplasm: • remainder of the contents of the cell consisting of: – Cytosol:liquid environment – Cytoskeleton: network of protein fibers that supports the shape of the cell and anchors its organelles and serves as a “track” for them to move on. Crisscrosses the cytoplasm А Mitochondria: “Powerhouse” • Provides energy for cell. – Converts food to usable energy for cell. • Have their own ribosomes and DNA. 寰Б Golgi Apparatus (Complex): “packaging and distributing center” • Stack of membrane-enclosed spaces. • Process/Sorts/Packages protein/lipids for distribution within the cell and export out of the cell. • Proteins/lipids come from endoplasmic reticulum. Endoplasmic Reticulum (ER): • (Highway) Set of channels…aids in movement of molecules inside the cell. • Rough ER: 첀Б – Ribosomes found on surface. • Smooth ER: – No ribosomes on surface. Ribosome (4d): • (Factory) Makes proteins and is found in the cytosol or on the ER. 첀Б Vacuole: “Storage Tanks” • Fluid filled sack. • Stores water, food molecules, ions and enzymes. • Animal cells contain many small vacuoles. • Plant cells contain a large central vacuole…we will be talking about this more later… 첀Б Lysosomes: “Suicide Sacs/Recycling Centers” • • 첀Б • • Carry enzymes to destroy cellular waste. – Break down damaged/worn out cell parts. Engulf/digest targeted molecules – Defend cell from invading bacteria/viruses Once thought to be only in animal cells, but exist minimally in plant cells. Membrane protects cell from enzymes. Plant Cell 첀Б Plant Cells: contain all of the previous organelles (except centrioles) as well as: Cell Wall: • Gives cells shape and support and provides protection. • Found in algae, fungi and most bacteria too. 첀Б Plant Cells: contain all of the previous organelles (except centrioles) as well as: Chloroplast: (green) • Changes sun’s energy into food. • Also in green algae. Plant Cells: contain all of the previous organelles (except centrioles) as well as: Central Water Vacuole: • Single, large water filled vacuole in the middle of the cell. • Strengthen cells and provide support for plant. • Contains toxins to harm plant predators, waste products and pigment for color (petals). 첀Б Animal Cell 첀Б Animal Cells contain all of the previous organelles plus: Centrioles: 2 cylindrical organelles (together called a centrosome) • Formed by hollow protein fibers called microtubules (part of the cytoskeleton) • Produce microtubules that aid in첀Б moving chromosomes during cell division. • Found in animals and algae only but not in all animal cells. Video tour of cell