Introduction What is Science 10 14 2012 Science as a process the process results in a body of knowledge Goal is to answer questions that we do not already have answers to create the body of knowledge an approach to understanding nature Use of evidence to construct testable explanations and predictions of natural phenomena as well as the knowledge generated through the process Name of the process Scientific Method What do Scientists Do They make observations Attempt to discern patterns Assume that the future is like the past Two important points about this scheme o Science only deals with phenomena that can be observed o We assume the future is like the past Scientific Method Observation o If you cannot observe a phenomenon you cannot do science on it limits of science o Ex Before the microscope no cell biology o Need technology technology changes science Generalization or Model o Take patterns and make a model o Models get better over time changes model or becomes more accurate Predictions or Hypothesis o Test the predictions or hypotheses Tests o Tests create a whole new set of observations o Start the cycle back over Outcome of the process better models o New observations either confirm the model or observations cause one to change the model and make it more accurate Goal of Science to make better models not reality not the best Copy truth vs science graph Hypothesis explanation or prediction untested very little validity Theory hypothesis that has been tested many times and always supported not completely confident has scientific weight and we believe accurate Law theory that has been extensively tested and confidently supported Terminology What is Biology Study of life Organization What are the Characteristics of Living Systems o Incredibly organized on many levels chemical cellular tissue organ systems populations o Important to see what level you are to understand o Emergent Properties properties that are not present at the preceding level due to the arrangement and interactions of parts as complexity increases Example photosynthesis takes place in the intact chloroplasts not in a disorganized mixture of chlorophyll and other molecules Energy use o need energy to organize Growth and Development change Reproduction mitochondria etc Evolution change of population o All life comes from preexisting life o Even on the cellular level mitochondria have same DNA as other o Occurs at the level of population o Happens from one generation to the next o Applies more to a group rather than an individual organism Response to environment maintain homeostasis None of these characteristics individually make one alive need all of these characteristics Approaches to Studying Biology Scale of Nature o Atomic 10 8 meters o Community Ecosystem 10 6 meters Reductionist take phenomena apart to study smallest pieces and study smallest parts o If you know a lot about the pieces you can understand a lot about the whole Holist New properties emerge as a whole o Must study it intact and as a whole as well as in pieces o There are some aspects of organisms that one must study intact e g behavior Start with reductionist approach Figure 1 4 Chapter 2 10 14 2012 Why is Atomic Structure Biologically important Organisms are composed largely of 11 basic elements Carbon hydrogen nitrogen oxygen What s the difference between the group of chemicals that make an organism and an actual living organism Organization Solubility Polarity Atoms Fundamental property that applies to biology What determines solubility like dissolves like Solvents and solutes that have similar properties work together polar solutes dissolve in polar solvents nonpolar solutes dissolve in nonpolar solvents o What determines polarity The types of bonds that hold the molecules together Smallest unit of matter separable by normal chemical means Smallest unit of an element that retains all of the elements properties An atom is composed of many smaller particles Subatomic Particles Proton mass of 1 dalton electric charge 1 Neutron mass of 1 dalton electric charge 0 o Protons and Neutrons located in nucleus Electron mass of 0 dalton electric charge 1 o Located in Electron cloud in orbit Atomic Number number of protons in an atom defines an atom Atomic Mass number of protons and neutrons in an atom approx Common Elements Hydrogen 1 proton 0 neutrons 1 electron A 1 AM 1 Helium 2 protons 2 neutrons 2 electrons A 2 AM 4 Nitrogen 7 protons 7 neutrons 7 electrons A 7 AM 14 Oxygen 8 protons 8 neutrons 8 electrons A 8 AM 16 Carbon 6 protons 6 neutrons 6 electrons A 6 AM 12 Carbon 14 isotope of carbon 6 protons 8 neutrons 6 electrons A 6 AM 14 o Same number of protons behaves the same chemically has all the same chemical properties as carbon but different mass o Change number of protons change the element Atomic Structure Helps explain how elements react Bohr Model o not the most accurate as far as where the electrons are o he observed that an atom was most stable that is unreactive when the outer most shell of electrons was full Electrons moving in orbitals or shells around the nucleus o The electrons always try to be in the lowest orbital or energy shell that is closest to the nucleus they fill the inside moving out o The lowest level K can contain 2 electrons o Next level L can contain 8 electrons o Next level M can also hold 8 o As you get further from the nucleus more energy is needed higher potential energy Valence Number of electrons that need to be gained or lost to fill the outer shell of electrons o Predicts the number of bonds an atom will form Atoms will try to gain or lose electrons in order to fill their outer shell or valence shell The number of electrons to be gained or lost is called the valence Examples o Hydrogen 1 electrons Valence 1 o Helium 2 electrons Valence 0 o Carbon 6 electrons Valence 4 o Nitrogen 7 electrons Valence 3 Helium is a noble gas doesn t bond or interact with anything Note Nitrogen can gain 3 or lose 5 it will gain 3 because it is the smaller number o Oxygen 8 electrons Valence 2 Valence electrons electrons in the outermost shell o Oxygen has a valence of 2 but 6 valence electrons Figure 2 05 actual pictures of electron cloud Some isotopes have the same number of electrons they have the same valence and generally the same chemical properties Chemical Bonds Form when atoms gain and lose or share electrons They are the result of electrical attractions between atoms Ionic Bonds bonds which are the result of very strong
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