General Biology - BIOL 1305
General Biology - BIOL 1305 BIOL 1305 - 001
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This 13 page Class Notes was uploaded by Bianka on Saturday August 27, 2016. The Class Notes belongs to BIOL 1305 - 001 at University of Texas at El Paso taught by Horacio O Gonzalez in Fall 2016. Since its upload, it has received 7 views.
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Date Created: 08/27/16
Chapter 1: Principles of Life 08/26/2016 ▯ Key Concepts ▯ 1.1 Living Organisms Share Common Aspects of Structure, Function, and Energy Flow ▯ 1.2 Genetic Systems Control the Flow, Exchange, Storage, and Use of Information ▯ 1.3 Organisms Interact with and Affect Their Environments ▯ 1.4 Evolution Explains Both the Unity and Diversity of Life ▯ 1.5 Science Is Based on Quantifiable Observations and Experiments ▯ ▯ Concept 1.1 Living Organisms Share Common Aspects of Structure, Function, and Energy Flow ▯ Biology—the scientific study of living things ▯ ▯ “Living things”—All the diverse organisms descended from a single-celled ancestor (a single common ancestor) ▯ ▯ Characteristics of “Living Things” ▯ Organized Structure made up of a cell or cells ▯ Metabolic Capability ▯ Respiration Capacity ▯ Energy Required to survive or sustain existence ▯ Responsive to external Stimuli ▯ Reproductive Capability ▯ Capacity to Adapt to Environment ▯ Growth Potential ▯ Mobility Capacity ▯ ▯ Characteristics shared by all living organisms: ▯ Organization made up of a cell or cells ▯ Composed of a common set of chemical components and similar structures ▯ Contain genetic information that uses a nearly universal code ▯ ▯ Characteristics shared by all living organisms: ▯ Metabolic Capacity, Respiration Capacity, and Energy Requirement for Survival or Sustaining Existence ▯ Convert molecules obtained from their environment into new biological molecules ▯ Extract energy from the environment and use it to do biological work ▯ Responsive to Stimuli ▯ Regulate their internal environment ▯ Reproductive Capability ▯ Replicate their genetic information in the same manner when reproducing ▯ Share sequence similarities among a fundamental set of genes ▯ • Capacity to Adapt to Environment ▯ Evolve through gradual changes in genetic information ▯ ▯ Earth formed between 4.6 and 4.5 billion years ago. ▯ It was some 600 million years or more before the earliest life evolved. ▯ ▯ ▯ ▯ Complex biological molecules possibly arose from random associations of chemicals in the early environment. ▯ Experiments that simulate conditions on early Earth show that this was possible. ▯ - Stanely Miller and Harold Urey (1950s), Joan Oro (1950s and 1960s), Bada (2000s) ▯ ▯ Critical step for evolution of life—formation of nucleic acids ▯ - Shown possible by Joan Oro in the 1950s ▯ ▯ Biological molecules were enclosed in membranes, to form the first cells. ▯ Formation of Fatty acids were essential in forming membranes. ▯ ▯ For 2 billion years, organisms were unicellular prokaryotes – similar to what we call extremophiles today. ▯ Early prokaryotes were confined to oceans, where they were protected from UV light. ▯ There was little or no O in the atmosphere, 2nd hence no protective ozone (O ) layer. 3 ▯ These early prokaryotes used Sulphate (SO ), Nitrate (NO ), Sulfur (S) or fumarate 42- 3- 2- - (C H2O 4 4 ), Carbon Dioxide (CO ) or Acetic Acid (C2 COO ) in place of O . 3 2 ▯ ▯ Photosynthesis evolved about 2.7 billion years ago. ▯ The energy of sunlight is transformed into the energy of biological molecules (sugars). ▯ Earliest photosynthetic cells were probably similar to cyanobacteria. ▯ O w2s a byproduct of photosynthesis, and it began to accumulate in the atmosphere. ▯ ▯ Figure 1.3 Photosynthetic Organisms Changed Earth’s Atmosphere (Part 2) ▯ ▯ Figure 1.3 Photosynthetic Organisms Changed Earth’s Atmosphere (Part 1) ▯ ▯ O 2as poisonous to many early prokaryotes. ▯ Organisms that could tolerate O evolved aerobic metaboli2m (energy production using O ), wh2ch is more efficient than anaerobic metabolism. ▯ Organisms were able to grow larger. Aerobic metabolism is used by most living organisms today. ▯ O 2lso produced a layer of ozone (O ) in the upper atmosphere. 3 ▯ This layer absorbs UV light, and its formation allowed organisms to move from the ocean to land ▯ ▯ Some cells evolved membrane-enclosed compartments called organelles. ▯ Example: The nucleus contains the genetic information. ▯ These cells are eukaryotes. ▯ Prokaryotes lack nuclei and other internal compartments. ▯ ▯ Some organelles may have originated by endosymbiosis, when larger cells engulfed smaller ones. ▯ Mitochondria (site of energy generation) probably evolved from engulfed prokaryotic organisms. ▯ Chloroplasts (site of photosynthesis) probably evolved from photosynthetic prokaryotes. ▯ ▯ Multicellular organisms arose about 1 billion years ago. ▯ Cellular specialization—cells became specialized to perform certain functions. ▯ Evolution of species: ▯ Mutations are introduced when a genome is replicated. ▯ Some mutations give rise to structural and functional changes in organisms, and new species arise ▯ Each species has a distinct scientific name, a binomial: ▯ • Genus name ▯ • Species name ▯ Example: Homo sapiens ▯ Evolutionary relationships of species can be determined by comparing genomes. ▯ A phylogenetic tree documents and diagrams evolutionary relationships. ▯ ▯ Relationships in the tree of life are determined by fossil evidence, structures, metabolic processes, behavior, and molecular analyses of genomes. ▯ Three domains of life: ▯ • Bacteria (prokaryotes) ▯ • Archaea (prokaryotes) ▯ • Eukarya (eukaryotes) ▯ ▯ Because all life is related, discoveries made using one type of organism can be extended to other types. ▯ Biologists use model systems for research, such as the green alga Chlorella to study photosynthesis. ▯ ▯ Concept 1.2 Genetic Systems Control the Flow, Exchange, Storage, and Use of Information ▯ Genome—the sum total of all the information encoded by an organism’s genes ▯ DNA consists of repeating subunits called nucleotides. ▯ Gene—a specific segment of DNA that contains information for making a protein ▯ Proteins govern chemical reactions in cells and form much of an organism’s structure. ▯ ▯ Figure 1.5 DNA Is Life’s Blueprint ▯ ▯ DNA Transcription and Protein Assembly Video: https://www.youtube.com/watch? v=nHM4UUVHPQM ▯ ▯ Mutations alter nucleotide sequences of a gene, and the protein is often altered as well. ▯ ▯ Mutations may occur during replication, or be caused by chemicals and radiation. ▯ Most are harmful or have no effect, but some may improve the functioning/ability of the organism and its descendent to survive. ▯ Mutations are the raw material of evolution. ▯ Complete genome sequences have been determined for many organisms ▯ http://www.ncbi.nlm.nih.gov/genome/browse/ ▯ ▯ Genome sequences are used to study the genetic basis of everything from physical structure to inherited diseases, and evolutionary relationships. ▯ ▯ Concept 1.3 Organisms Interact with and Affect Their Environments ▯ Biological systems are organized in a hierarchy. ▯ Traditionally, biologists concentrated on one level of the hierarchy, but today much biology involves integrating investigations across many levels. ▯ ▯ System: a set of interacting parts for which neither the parts nor the ▯ whole can be understood without taking into account the interactions. ▯ ▯ Living organisms acquire nutrients from their environments. ▯ Nutrients supply energy and materials for biochemical reactions. ▯ Biochemical reactions break nutrient molecules into smaller units, releasing energy for work and then build new molecules from the smaller units and energy. ▯ ▯ Examples of cellular work: ▯ Catabolism: Breaking down complex molecules to their smaller chemical units ▯ Synthesis (Anabolism): Building new complex molecules from smaller chemical units ▯ Movement of molecules (in the cell or throughout the organism), or movement of the whole organism ▯ Electrical work of information processing in nervous systems ▯ ▯ Metabolism is the sum total of all chemical transformations and other work done in all cells of an organism. ▯ The reactions are integrally linked—the products of one are the raw materials of the next. ▯ We can think of metabolism like products being produced from raw materials through several steps and factories. ▯ ▯ In multicellular organisms, cells are specialized, or differentiated. ▯ Differentiated cells are organized into tissues. ▯ Tissue types are organized into organs, and organ systems are groups of organs with interrelated functions. ▯ ▯ Multicellular organisms have an internal environment that is partially acellular—an extracellular environment of fluids. ▯ Homeostasis—maintenance of a narrow range of conditions in this internal environment that make life possible. ▯ Regulatory systems maintain homeostasis in both multicellular organisms and in individual cells. ▯ ▯ Organisms interact: ▯ Population—group of individuals of the same species that interact with one another ▯ A community—populations of all the species that live in the same area and interact ▯ Communities plus their abiotic environment constitute an ecosystem. ▯ ▯ Individuals may compete with each other for resources, or they may cooperate (e.g., in a termite colony). ▯ Plants also compete for light and water, and many form complex partnerships with fungi, bacteria, and animals. ▯ ▯ The Queen of Trees Documentary ▯ ▯ Species interaction with one another and with their environment is the subject of ecology ▯ Interactions of plants and animals are major evolutionary forces that produce specialized adaptations. ▯ ▯ Concept 1.4 Evolution Explains Both the Unity and Diversity of Life ▯ ▯ Evolution is a change in genetic makeup of biological populations through time—a major unifying principle of biology. ▯ Charles Darwin proposed that all living organisms are descended from a common ancestor by the mechanism of natural selection. ▯ Natural selection leads to adaptations—structural, physiological, or behavioral traits that enhance an organism’s chances of survival and reproduction ▯ ▯ In science, a theory is a body of scientific work in which rigorously tested and well- established facts and principles are used to make predictions about the natural world. ▯ Evolutionary theory is: ▯ (1) a body of knowledge supported by facts ▯ (2) the resulting understanding of mechanisms by which populations have changed and diversified over time, and continue to evolve ▯ ▯ Evolution can be observed and measured by: ▯ Changes in genetic composition of populations and between species in short time frames ▯ The fossil record—population changes over very long time frames ▯ ▯ Concept 1.5 Science Is Based on Quantifiable Observations and Experiments ▯ ▯ Scientific investigations are based on observation and experimentation. ▯ Understanding the natural history of organisms—how they get food, reproduce, behave, regulate internal environments, and interact with other organisms—facilitates observation and leads to questions. ▯ ▯ Observation is enhanced by technology: microscopes, imaging, genome sequencing, and satellites. ▯ Observations must be quantified by measurement and mathematical and statistical calculations. ▯ ▯ The scientific method (hypothesis–prediction (H–P) method): ▯ Observations ▯ Questions ▯ Hypotheses ▯ Predictions ▯ Testing ▯ ▯ Inductive logic leads to tentative explanations called hypotheses. ▯ Deductive logic is used to make predictions. ▯ Experiments are designed to test these predictions. ▯ ▯ Controlled experiments manipulate the variable that is predicted to cause differences between groups. ▯ Independent variable—the variable being manipulated ▯ Dependent variable—the response that is measured ▯ ▯ ▯ Comparative experiments look for differences between samples or groups. ▯ The variables cannot be controlled; data are gathered from different sample groups and compared. ▯ E.g., Epidemiological and Field Studies ▯ ▯ Statistical methods help scientists determine if differences between groups are significant. ▯ Statistical tests start with a null hypothesis—that no differences exists. ▯ Statistical methods eliminate the possibility that results are due to random variation. ▯ ▯ Not all forms of inquiry into nature are scientific. ▯ Scientific hypotheses must be testable, and have the potential of being rejected. ▯ Science depends on evidence that comes from reproducible and quantifiable observations. ▯ ▯ Religious or spiritual explanations of natural phenomena are not testable and therefore are not science. ▯ Science and religion are largely non-overlapping approaches to inquiry because science deals with the natural world of repeatable events. ▯ ▯ Scientific advances that may contribute to human welfare may also raise ethical questions. ▯ Science describes how the world works; it is silent on the question of how the world “ought to be.” ▯ Contributions from other forms of human inquiry may help us come to grips with such questions. ▯ ▯ ▯ ▯