Intro to Science Sept 2011 Biology 112

The Goals of Science Deals only with the Natural World The supernatural is outside the realm of science

The Goals of Science Collect & Organize Data

Goals of Science 3. Propose Explanations that can be tested

In Summary….. SCIENCE is a BODY of KNOWLEDGE that EXPLAINS the NATURAL World.

Science Begins with Observation – How are your Skills?

OBSERVATION Quantitative – a quantity/number or measure Qualitative – a quality/characteristic; description

Inference A logical interpretation based on prior knowledge Examples of Inferences? What can be the problem with inferences? http://www.youtube.com/watch?v=tiy1MeXzhfA

Hypothesis A proposed explanation; must be TESTABLE; written in an “If….then” format If I give my dog Purina dog food for a month, then he will not shed as much. If I use miracle grow then my plants will produce more tomatoes. If I use the drug Avapro for a week then my blood pressure will be lower

Scientific Inquiry~ inquisitive thinker’s!!! Scientists make observations, ask questions and then try to answer them through research and experimentation. http://www.youtube.com/watch?v=VjE0Kdfos4Y

Narrowing in on Science BIOLOGY – One Branch of Science Study of LIVING things 

Copyright Pearson Prentice Hall A Few Branches of Biology: Zoologists Botanists Paleontologists Cell Biologists Geneticists Microbiologists Ecologists Copyright Pearson Prentice Hall 13

Biology is very broad (Remember it is the study of LIVING things…and there are LOTS of living things!!!!!) Terminology rich; very descriptive and has it’s own language~ – Handout #1 – Give it a try 

Answers: Learning the Language Hydrology – study of water Cytology - study of structure & function of cells Protozoa – first animal Epidermis – above skin Spermatogenesis – beginning sperm Cytoskeleton – cell skeleton Abiotic – not living Dermatitis – skin disease / inflammation Hypodermic – below the skin Hemophilia – blood like

Answers: Learning the Language Endocytosis – internal cell Insecticide – killer of insects Anaerobic – not needing oxygen Bilateral – two, twice, double sided, both sides Endotherm – internal heat Subspecies – species below Arthropod – joint footed Micrometer - small measurement Hypothermia – below heat Morphology – study of form

Copyright Pearson Prentice Hall 1-2 How Scientists Work Scientists make educated guesses about how things work the way they do. These are called HYPOTHESIS. How do scientists test hypotheses? A hypothesis should be tested by an experiment in which only one variable is changed at a time. Copyright Pearson Prentice Hall 17

Scientific Method Summary Ask questions, make observations Gather information Form a hypothesis (educated guess) Set up a controlled experiment Manipulated variable - the variable that is deliberately changed (aka independent variable) Responding variable is variable that is observed (aka dependent variable) 5)Record and analyze results 6)Draw a conclusion 7)Repeat & share findings

Scientific Method – Step 1: Ask Questions/Make Observations: 2300 years ago people thought that some “special force” brought some things into being from nonliving material Ex: Beetles just “appeared” on cow dung Mice were “found” on grain Maggots “showed up” on meat Good thing we don’t’ just rely on observations!!!

Copyright Pearson Prentice Hall The idea that living things arise from non-living matter is called: spontaneous generation OR abiogenesis. In Aristotle’s time, people hypothesized that maggots spontaneously appeared on meat. FRANCESCO REDI – BEGAN CHALLENGING ARISTOTLE BY ASKING QUESTIONS and Following the steps of the scientific method!! In 1668, Redi proposed a different hypothesis: that maggots came from eggs that flies laid on meat. Copyright Pearson Prentice Hall 20

Copyright Pearson Prentice Hall Redi’s Experiment Uncovered jars Covered jars Controlled Variables: jars, type of meat, Location, temperature, time In a controlled experiment, only one variable is tested at a time. Redi designed an experiment to determine what caused the sudden appearance of maggots. In his experiment, the manipulated variable was the presence or absence of the gauze covering. The results of this experiment helped disprove the hypothesis of spontaneous generation. What do you think are the manipulated and responding variables in this experiment?? Copyright Pearson Prentice Hall 21

John Needham – mid 1700’s – SG is BACK!??? English Scientist who tried to attack Redi’s work. He heated a flask of gravy for a short time and corked the flask and microorganisms appeared. He believed that the little “animalcules” must have come from the gravy!

Repeating Investigations – TRIALS!!! Spallanzani's Test of Redi's Findings  Gravy is boiled. Gravy is boiled. Spallanzani’s experiment showed that microorganisms will not grow in boiled gravy that has been sealed but will grow in boiled gravy that is left open to the air. Interpreting Graphics What variable was controlled in this experiment? Which variables are controlled?? Copyright Pearson Prentice Hall 23

Spallanzani – Disproving SG! Flask is open. Flask is sealed. Is the flask the manipulated or responding variable?? Copyright Pearson Prentice Hall 24

Copyright Pearson Prentice HallH Gravy is teeming with microorganisms. Gravy is free of microorganisms. Helped prove the theory of BIOGENESIS!!!! Living things come from other living things! Copyright Pearson Prentice HallH 25

Copyright Pearson Prentice Hall Pasteur's Test of Spontaneous Generation Louis Pasteur conclusively disproved the hypothesis of spontaneous generation. Pasteur showed that all living things come from other living things. Copyright Pearson Prentice Hall 26

Copyright Pearson Prentice Hall Pasteur’s Experiment Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Pasteur’s experiment showed that boiled broth would remain free of microorganisms even if air was allowed in, as long as dust and other particles were kept out. Broth is boiled Copyright Pearson Prentice Hall 27

Copyright Pearson Prentice Hall The Impact of Pasteur’s Work He began to uncover the nature of infectious diseases, showing that they were the result of microorganisms. Pasteurization of dairy products  Copyright Pearson Prentice Hall 28

SCIENTIST SUMMARY: PRO SG: Aristotle, Needham ANTI SG: Redi, Spallanzani, Pasteur

Copyright Pearson Prentice Hall 1-3 Studying Life Photo Credit: © Andrew Syred/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall 30

Copyright Pearson Prentice Hall So…If Biology is the study of living things…. What makes something living? Copyright Pearson Prentice Hall 31

Copyright Pearson Prentice Hall Living things share the following characteristics: *REFERENCE PAGE – pages 16/17 of student text!! 1. Made of cells Copyright Pearson Prentice Hall 32

2. Reproduction Reproduction

3. Universal genetic code

4. Grow & Develop

5. obtain and use materials and energy

6. respond to stimuli

7. Maintain a stable internal environment (called homeostasis/equilibrium)

8. change over time

Make a table with the heading “CAR” Living NonLiving

Microscopes Anton van Leeuwenhoek (1632-1723) was responsible for the first “microscope” as we know them today Due to his knowledge of lenses he was able to construct a piece of equipment that made things appear closer and larger.

Microscopy and Measurement Microscopes – produce an enlarged image of an object Used to study organisms, cells, and cell parts Increase in apparent size is called magnification The ability to show details clearly is called resolution Microscopes vary in both magnification and resolution

Compound Light Microscope (2 lens-microscope) Uses light passing through a medium of liquid to view a specimen Uses generally a 10X ocular lens in addition to a 4x, 10x, 40x objective lens Magnification = ocular x objective Limited in it’s magnification Used to view living and dead specimens

Magnification Example: Using the compound microscope in your classroom, you are asked to view a piece of hair under the medium power objective. What is the total Magnification of the hair being viewed? What exactly does that mean?

Types of MICROSCOPES Light vs. Electron Smallest size seen with the Naked Eye is…. 0.2mm = one ridge on your finger print (resolution OR resolving power) Light Microscopes can view 0.0002 mm Electron Microscopes can view 0.000000002 mm (0.2 nm)

Parts of the Compound Microscope – Fill in your sheet as we go!! http://www.biologycorner.com/microquiz/#

Parts of the Compound Microscope Stage – supports the slide. The central opening in the stage allows light to pass through. Clips – Keep the slide in position Diaphragm – Regulates the amount of light reaching the object being viewed Revolving Nosepiece – changes the objective lenses Ocular Lens – Viewing (10X)/Eyepiece Course Adjustment – Moves the body tube up or down so you can get the specimen in focus. It is used with the low power objective only! Fine Adjustment – Used with med or high power to get the specimen in sharper focus Condenser Lens – Directs light to the object or specimen.

Microscope Use http://www.youtube.com/watch?v=scEhgAiazzU

Focusing a Microscope Always start with the low power objective (4X). Odds are, you will be able to see something on this setting. Use the Coarse Knob to focus. Once you've focused on low power, switch to Med Power (10X). Use the Coarse Knob to refocus. Again, if you haven't focused on this level, you will not be able to move to the next level. Now switch to High Power. (40X) If the specimen is too light or too dark, try adjusting the diaphragm.

Making a Wet Mount Gather a thin slice/piece of whatever your specimen is. your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw, and you will not be able to view it under High Power. Place ONE drop of water/dye directly over the specimen. If you put too much water, then the coverslip will float on top of the water, making it hard to draw the specimen, because they might actually float away. (Plus too much water is messy) Place the coverslip at a 45 degree angle (approximately) with one edge touching the water drop and then gently let go. Performed correctly the coverslip will perfectly fall over the specimen

Finished with your Microscope? 1. Store microscopes with the scanning objective (4X) in place. 2. Wrap cords and cover microscopes. 3. Wash slides/slips in the sinks and dry them, placing them back in the slide boxes to be used later. 4. Carry with 2 hands (arm/base) 5. Put back in the correct location

Transmission Electron Microscope Uses electrons instead of light Capable of over 1,000,000X magnification Specimens that contain many layers of cells, such as blood vessels, cannot be examined A thick specimen would absorb all the electrons and produce a blackened image Only view thin sections encased in plastic Size of Specimen 1 to 5 nm in size

TEM cont..

Smooth Muscle Cells http://www.fmhs.auckland.ac.nz/sms/biru/gallery/tem-images.aspx

Negative Stain Rota Virus http://www.ualberta.ca/~mingchen/images.htm

Negative Stain Corona Virus (Animal Virus) http://www.ualberta.ca/~mingchen/images.htm

Scanning Electron Microscope (SEM) Produces a 3-D image View up to 300,000X CHANGE Takes “pictures” of surfaces Specimens are usually preserved, coated in a metal, dehydrated…so specimen being viewed is non-living. http://www.purdue.edu/rem/rs/sem.htm Add in: Size of Specimen 1 to 5 nm in size http://www.fei.com/uploadedfiles/documents/content/2006_06_allyouwanted_pb.pdf

Scanning Electron Microscope

SEM cont…

Guess?

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TYPES OF MICROSCOPE COMPOUND LIGHT TRANSMISSION ELECTRON SCANNING ELECTRON HOW IMAGE IS FORMED LIGHT WAVES ELECTRON BEAM MAGNIFICATION 1000 X (2000X) 1 000 000 X 300 000 X THICKNESS (IMAGE) WHOLE OR PART THIN 3-D COVERED IN GOLD SIZE 0.2 um (200 nm) 10 nm – 100 nm 1 nm – 5 nm ALIVE OR DEAD BOTH DEAD MEDIUM LIQUID VACUUM (STAINING)

Rules for Biological Diagrams See handout (rules/practice assessment)

Figure 1 – Moss Cross-section

Biological Diagrams - Lab #1 Following all steps for biological diagrams complete the following: (Do two drawings on one page of plain paper) Obtain a sample from the front and draw the specimen in the container (do not draw the bottle)