General Biology 121- Chapter 1: Evolution, Biological Themes, and Scientific Inquiry
General Biology 121- Chapter 1: Evolution, Biological Themes, and Scientific Inquiry Bio 121
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This 10 page Class Notes was uploaded by Audrey Notetaker on Saturday September 12, 2015. The Class Notes belongs to Bio 121 at Syracuse University taught by Wiles in Fall 2015. Since its upload, it has received 21 views. For similar materials see Intro to biological sciences in Biological Sciences at Syracuse University.
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Date Created: 09/12/15
Chapter 1 Evolution Biological Themes and Scienti c Inquiry Inquiring About Life 0 A process of change that has transformed life on Earth from its earliest beginnings to the diversity of organisms living today Evolution is the fundamental organizing principle of biology 0 Evolution makes sense of everything we know about biology Organisms are modi ed descendents of common ancestors 0 Evolution explains patterns of unity and diversity in living organisms Questions about the living world and seeking answers through scienti c inquiry are central activities of biology Biology is a quest It s an ongoing inquiry about the nature of life 0 Some properties of life are order energy processing evolutionary adaptation growth and development response to the environment regulation and reproduction The Study of Life Reveals Common Themes 0 5 Unifying Themes Ways of Thinking About Life Organization Information Energy and Matter Interactions Evolution LJ39gtLJLJII I Theme New Properties Emerge at Successive Levels of Biological Organization 0 Levels of Biological Organization 1 It consists of all life on Earth and all the places where life exists It includes most regions of land most bodies of water atmosphere to an altitude of several kilometers and sediments below the ocean oor 2 It consists of all living things in a particular area with nonliving components of the environment with which life interacts like soil water atmospheric gases and light Examples of these areas are grasslands deserts and coral reefs 3 An array of organisms inhabiting a particular ecosystem The following organisms animals fungi mushrooms and bacteria are also called species gt l 00 9 10 All living organisms within the bounds of a speci ed area Example whitetailed deer and sugar maple trees Individual living things Organs are body parts made out of multiple tissues in which they carry out a particular function in the body Organs are organized into organ systems These systems are a team of organs that cooperate in a bigger funcUon A group of cells that work together to perform a specialized function Cells are life s fundamental unit of structure and function Some organisms are either single cellular or multicellular A single cell organism performs all the functions of life while a multicellular organism has a division of labor among specialized cells Organelles are various functional components present in cells They re chemical structures consisting of 2 or more units called atoms The process of reducing complex systems to simpler components that is manageable to study It s a powerful strategy in biology For example by studying the molecular structure of DNA that had been extracted from cells James Watson and Francis Crick were able to infer the chemical basis of biological inheritance However reductionism provides a necessarily incomplete view of life on Earth 0 They re new properties that arise with each step upward in the hierarchy of life owing to the arrangement and interactions of parts as complexity increases 0 Isolated components of living systems serving as the object of study in a reductionist approach to biology lack a number of signi cant properties that emerge at higher levels of organizing Emergent properties aren t unique to life For example a box of bike parts won t get you anywhere but if they re put together you can travel to your destination Systems biology The exploration of a biological system by analyzing the interactions among its parts This is used to understand emergent properties more fully and it can be used to study life at all levels Biologists complement reductionism with systems biology o By examining and modeling the dynamic behavior of an integrated network of components systems biology enables us to pose new kinds of questions 0 Structure and Function 0 Analyzing a biological structure gives us clues about what it does and how it works 0 Knowing the function of something provides insight into its structure and organization 0 For example a hummingbird s anatomy allows the wings to rotate at the shoulder so hummingbirds have the ability to y backward or hover in place While hovering the birds can extend their long beaks into owers and feed on nectar o The Cell An Organism s Basic Unit of Structure and Functioning o A cell is the smallest unit of an organism that can perform all activities required for life 0 Actions of organisms are based on the cells functions 0 For example eye movement as you read sentences activities from muscle and nerve cells result All cells share certain characteristics 0 Every cell is enclosed by a membrane that regulates the passage of materials between the cell and its surroundings 2 main forms of cells 1 These are cells that are comprised of two groups of singlecelled microorganisms bacteria and archaea These kinds of cells lack a nucleus or other membraneenclosed organelles They re also smaller than eukaryotic cells 2 These are all other forms of life both plants and animals They contain membraneenclosed organelles Some organelles are found in the cells of all eukaryotes while other organelles are speci c to particular cell types 0 O Theme Life39s Processes Involve the Expression and Transmission of Genetic Information 0 Within cells structures called chromosomes have genetic material in the form of DNA 0 Each time a cell divides the DNA is rst replicated or copied and each of the two cell offspring inherits a set of chromosomes identical to the parent cell 0 Each chromosome has one long DNA molecule with hundreds or even thousands of genes each a section of the DNA of the chromosome are units of inheritance They encode the information necessary to build all of the molecules synthesized within a cell which establish that cell s identity and function We begin as a single cell stocked with DNA inherited from our parents DNA replication during each round of cell division transmits copies of the DNA to become the trillions of cells of our body As the cells increase and are divided genetic information encoded by the DNA directs our development DNA s molecular structure accounts for its ability to store information A DNA molecule is made up of two long chains strands arranged in a double helix Each chain is made of four kinds of chemical building blocks called nucleotides A T G and C Nucleotides are like a 4letter alphabet Speci c sequences of these four nucleotides encode the information in genes Genes provide blueprints for making proteins Proteins are major players in building and maintain the cell and carrying out its activities Genes control protein production indirectly using RNA as an intermediary A sequence of nucleotides along a gene is transcribed into RNA which are then translated into a linked series of protein building blocks called amino acids Information in a gene that directs the manufacturing of a cell product In translating genes into proteins all forms of life employ essentially the same a certain sequence of nucleotides say the same thing in one organism as it does in another RNA molecules mRNAs can be translated into proteins RNA can regulate the functioning of proteincoding genes RNAs are speci ed by genes and production of RNAs is referred to as gene expression DNA is responsible for carrying the instructions for making proteins and RNAs lt s replicated with each cell division An a particular protein is required to break down a sugar molecule while a human gene may denote a different protein called an antibody Genomics LargeScale Analysis of DNA Sequences o An entire library of genetic instructions that an organism inherits 0 Researchers study whole sets of genes in one or more species an approach called o the study of sets of proteins and their properties An entire set of proteins expressed by a given cell or group of cells is called a proteome o The uses of computational tools to store organize and analyze the huge volume of data that results from highthroughput methods Theme Life Requires the Transfer and Transformation of Energy and Matter One characteristic of living organisms is their use of energy to carry out life s activities The input of energy primarily from the sun and the transformation of energy from one form to another make life possible Leaves absorb sunlight and molecules within the leaves convert the energy of sunlight to the chemical energy of food like sugars producing during photosynthesis That chemical energy in the food molecules is passed along by plants and producers to consumers like animals that feed on producers and other consumers Organisms use chemical energy to perform work and that energy is lost to heat s surroundings The result is energy goes to the ecosystem and it enters as light Then it exits the ecosystem as heat Chemicals are recycled within an ecosystem For example a certain plant absorbs chemicals from the air or soil and they re incorporated into the plant s body and then an animal comes to eat the plant The chemicals are then passed to the animal Chemicals are returned to the environment by decomposers like bacteria and fungi that break down waste and the bodies of dead organisms Chemicals are then available to be taken up by plants again completing the cycle Theme from Ecosystems to Molecules Interactions are Important in Biological Systems Ecosystems An Organism s Interactions with Other Organisms and the Physical Environment 0 O 0 Sometimes interactions between organisms are mutually bene cial Sometimes one of the organism bene ts and the other is harmed Sometimes both of them are harmed Interactions help regulate the functioning of the ecosystem as a whole Organisms also interact with physical factors in their environment For example tree leaves absorb light from the sun take in carbon dioxide from the air and release oxygen into the air The environment is also affected by organisms For example the roots of a plant break up rocks as they grow contributing to the formation of soil Plants and other synthetic organisms have generated all the oxygen in the atmosphere Molecules Interactions within Organisms O 0 Within lower levels of organisms interactions between components that make up living organisms are crucial to smooth operation Interactions among the body s molecules are responsible for most steps in the process During most chemical activities in the cell those that either decompose or store sugar are accelerated at the molecular level by proteins called enzymes Each type of enzyme catalyzes a speci c chemical reaction These reactions are linked into chemical pathways each step with its own enzyme The ability of many biological processes to selfregulate by a mechanism is called a control mechanism that uses the output or product of a process to regulate the rate at which the process occurs a loop in which the response reduces the initial stimulus the end product increases its own production Interactions between organisms can affect systemwide processes like growth of a population Feedback is a regulatory common motif Evolution the Core Theme of Biology 0 We can explain the sharing of traits by 2 organisms with the premise that the organisms have descended from a common ancestor and we can account for differences with the idea that heritable changes have occurred along the way Core Theme Evolution Accounts for the Unity and Diversity of Life 0 Evolutionary mechanisms account for the unity and diversity of all species on Earth 0 Classifying the Diversity of Life 0 Grouping Species the Basic Idea the branch of biology that names and classi es species formalizes the ordering of species into groups of growing breadth based on the degree to which they share characteristics 0 3 Domains of Life They re kingdoms of life grouped into 3 higher levels of classi cation Bacteria and archaea are prokaryotic Eukaryotes are eukarya Prokaryotes and eukaryotes are distinguished by modes of nutrition The 3 kingdoms of multicellular eukaryotes are plantae fungi and animalia 1 They produce their own sugars and other food molecules by photosynthesis 2 r They ingest other organisms 3 They absorb dissolved nutrients from their surroundings 4 They re unicellular but have some simple multicellular relatives Charles Darwin and the Theory of Natural Selection 0 Darwin published the book On the Origin ofSpecies in 1859 o The book made two important points 1 Contemporary species arose from a succession of ancestors that differed from them 2 An evolutionary mechanism for descent for modi cation 0 Individuals in a population vary in their traits many of which seem to be heritable o A population can produce more offspring than can survive to produce offspring of their own If there were more individuals than the environment then the competition was inevitable 0 Darwin said that individuals with inherited traits that are better suited to the local environment are more likely to survive and reproduce than less wellsuited individuals Years later a higher proportion of individuals in a population will have the advantageous traits Evolution occurs as the unequal reproductive success of individuals leads to adaptation to their environment as long as the environment is the same or similar 0 Natural selection the natural environment chooses the propagation of certain traits among naturally occurring variant traits in the population 0 Natural selection has the ability to edit a population s heritable variations in color The products of natural selection in the exquisite adaptations of different organisms to the special circumstances of their way of life and environment 0 Example A Beetle population colonized a locale where the soil has been blackened by a re The population varies in the inherited coloration of the individual beetles from light grey to charcoal Because of this hungry birds primarily eat the lighter beetles since they re easier to spot Scientists Make Observations and Form and Test Hypotheses Making Observations o The gathering of information either through direct use of the senses or with the help of tools They can reveal valuable information about the natural world 0 Recorded observations 0 Collective and analyzing observations can lead to important conclusions based on a type of logic Generalizations are derived from a large number of speci c observations Forming and Testing Hypotheses o A tentative answer to a wellframed question an explanation on trial 0 A scienti c test carried out under controlled conditions 0 Sometimes we can t carry out an experiment but can test a hypothesis using observations 0 Involves logic that ows in the opposite direction from the general to speci c Deductions usually take form of predictions of results that ll be found if a particular hypothesis premise is correct Hypotheses are tested by carrying out experiments or observations to see if the results were as predicted They involve quotIfthenquot statements 0 2 key points about hypotheses O 1 Initial observations may give rise to multiple hypotheses 2 We can t prove that a hypothesis is true A hypothesis must be testable and falsi able The Flexibility of the Scienti c Processes O An idealized process of inquiry Experiment Variables and Controls 0 O 00 An experiment involves manipulation of one factor in a system to see if the effects change it Variables factors that vary in an experiment Controlled experiment it s designed to compare an experimental group with a controlled group Experimental and control groups are designed to differ in the one factor the experiment is testing the factor manipulated the factor being measured in the experiment and what is being affected in the experiment It responds to and depends on the independent variable
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