Chapter - 1 - An Introduction to An Biology Biology Chapter...

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Unformatted text preview: An Introduction to An Biology Biology Chapter 1 Properties of Life Unity – All modern forms of life display a common set All of characteristics of – Based on biological evolution Diversity – Many types of environments with diverse Many organisms organisms Seven Characteristics of Life 1. 2. 3. 4. 5. 6. 7. Cells and organization Energy use and metabolism Response to environmental changes Regulation and homeostasis Growth and development Reproduction Biological evolution Levels of Organization 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Atoms Molecules and macromolecules Cells Tissues Organs Organism Population Community Ecosystem Biosphere Evolutionary History Life began on Earth as primitive cells 3.5-4 billion years ago 3.5-4 Primitive cells - evolutionary changes - rise to the species Primitive we see today we Understanding evolutionary history helps us understand Understanding the structure and function of an organism’s body Two mechanisms of evolutionary change 1. Vertical descent with modification – – – Progression of changes in a lineage New species evolve from pre-existing species New by the accumulation of mutations by Natural selection takes advantage of beneficial Natural mutations mutations Tree of life focuses on vertical evolution 1. Horizontal gene transfer – – – Genetic exchange between different species Relatively rare Genes that confer antibiotic resistance are Genes sometimes transferred between different bacteria species bacteria Web of life includes the Web contribution of horizontal gene transfer gene Classification Taxonomy is the grouping of species based on common ancestry on 3 domains – – – Bacteria- unicellular prokaryote Archaea- unicellular prokaryote Eukarya- unicellular to Eukarya- multicellular eukaryotes multicellular 4 kingdoms – Protista, fungi, plantae and animalia A species is placed into progressively species smaller groups that are more closely related evolutionarily evolutionarily Approach emphasizes the unity and Approach diversity of different species diversity Jaguar example Genomes and Proteomes Genome – The complete genetic makeup of an organism Evolutionary history and relatedness of all living organisms Evolutionary Genomics – Techniques used to analyze DNA sequences in genomes Proteomes – The complete complement of proteins that a cell or organism can make The genome carries the information to make its proteome Proteomics – Techniques used to analyze the proteome of a single species and the comparison of proteomes of different species Biology as a scientific discipline Science is the observation, identification, experimental Science investigation, and theoretical explanation of natural phenomena phenomena The scientific method is used to test theories Some scientists also gather information Investigate life at different levels How science is done Hypothesis or theory? Hypothesis – Proposed explanation for a natural Proposed phenomenon phenomenon – Educated guess based on previous observations Educated or experimental studies or Hypothesis must make predictions that can be shown to be correct or incorrect Additional observations or experiments support or reject a hypothesis A hypothesis is never really proven – We may not have found the true explanation for a phenomenon Theory – Broad explanation of some aspect of the natural world Broad that is substantiated by a large body of evidence that – Allows us to make many predictions – Also can never be proved true Due to overwhelming evidence, extremely likely to be true Example – The theory that DNA is the genetic material – Overwhelming body of evidence supports this theory Two key attributes of a theory 1. 2. Consistency with a vast amount of known data Ability to make many correct predictions Understanding biology Curiosity is the key Not a rigid set of steps 2 general approaches 1. Discovery-based science 2. Hypothesis testing Types of reasoning Deductive reasoning: Applies general principles to predict specific results. For example: Species of an organism can be deduced from its characteristics. Inductive reasoning: Uses specific observations to construct general scientific principles. Discovery-based science Collection and analysis of data without Collection the need for a preconceived hypothesis the Goal is to gather information – Test drugs to look for action against Test disease disease – Sequence genomes and proteomes Often leads to hypothesis testing Hypothesis Testing/Scientific Method Five stages 1. Observations are made regarding natural phenomena. 2. These observations lead to a hypothesis that tries to These explain the phenomena. As mentioned, a useful hypothesis is one that is testable because it makes specific predictions. specific 3. Experimentation is conducted to determine if the Experimentation predictions are correct. predictions 4. The data from the experiment are analyzed. 5. The hypothesis is accepted or rejected. Common features Data are often collected in two parallel manners – Control and experimental sample – Differ by only one factor Data analysis – Statistically significant differences – Apply statistical analyses to determine if the control Apply and experimental samples are likely to be different from each other because of the single variable that is different between the two samples different If the two sets of data are found not to be significantly different, we would reject our hypothesis. Alternatively, if the differences between the two sets of data are significant, we would accept our hypothesis, though it is not proven Cystic Fibrosis Affects about 1 in every 3,500 Americans Persons with CF produce abnormally thick and sticky Persons mucus that obstructs the lungs and pancreas mucus Average lifespan for people with CF is currently in their Average mid- to late 30s mid1945, Dorothy Anderson determined that cystic fibrosis is a genetic disorder Discovery-based sciences used to find CF gene 1989, research groups headed by Lap-Chi Tsui, Francis Collins, and John Riordan identified the CF gene CF Gene and Hypothesis Researchers hypothesize that the CF gene encodes a Researchers protein that transports chloride ions (Cl-) across the protein across membrane of cells membrane Led to experiments to test normal cells and cells from CF Led patients for their ability to transport Clpatients – CF cells were found to be defective in chloride CF transport transport – Transferring a normal CF gene into cells in the lab Transferring corrects this defect corrects In this example, hypothesis testing In has provided a way to accept or reject an idea regarding how a disease is caused by a genetic change change ...
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