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Chapter 1

Chapter 1: Studying Life.docx

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CAS BI 108
Francis Monette

BI108 Chapter 1 Notes: The Study of Life Biology: the scientific study of living organisms Characteristics of Living Organisms: • Made up of carbs, fatty acids, nucleic acids, ect. • Cells: individual structures enclosed by plasma membranes; building blocks of life/organisms o Extract energy from environment to do biological work • Contain genetic info (universal code for assembly of proteins) • Exist in populations (evolve) • Self-regulate internal environments All life has a common ancestry • Nearly universal genetic code (common set of amino acids) LifeArose from non-life via chemical evolution • Complex biological molecules arose through random physical association of chemicals • Appearance of NucleicAcids: crucial step for evol/life; molecules reproduce themselves (templates for synthesis of proteins) Cell Structure evolved in common ancestor • Complex proteins/bio molecules enclosed by membrane (compact internal environment) • FattyAcids—can’t dissolve in water; membranous films • Internal Environment: concentrated products/reactants—rxns controlled within a cell • Membrane formation resulted in first cells w/ability to reproduce (*evolution of first cellular organisms) • Unicellular organisms enclosed by single outer membrane: Prokaryotes o Bacteria and Archaea • Eukaryotes: external and internal membranes; internal to enclose organelles within cells o Contain nucleus (holds genetic info/mitochondria) o At some point, the cells of Eukaryotes failed to separate after cell division—this made it possible for cells to specialize in certain functions... o Cellular Specialization: enabled multicellular eukaryotes to increase in size and become more efficient at gathering resources/adapting to environments Photosynthesis • In order to fuel cellular metabolism, prokaryotes took in molecules directly from their environment and broke them down (releasing energy held in chemical bonds) • Photosynthesis: transforms the energy of sunlight into a form of biological energy; powers synthesis of large molecules, which are then broken down to provide metabolic energy o Energy capturing processes provide food for other organisms • Photosynthetic prokaryotes became so abundant that large quantities of oxygen gas accumulated in the atmosphere BI108 Chapter 1 Notes: The Study of Life o However, during the early eons of life there was no O in 2he atmosphere, in fact, it was poisonous to many prokaryotes o As time moved on, organisms that did tolerate were able to survive • And hence, two new avenues of evolution: o Aerobic Metabolism: biochemical process that uses O to ext2act energy from nutrient molecules (very efficient) o Anaerobic Metabolism: does not use O 2 • Additionally, oxygen made it possible for life to move onto land o For majority of life on Earth UV too intense for surface life, until ozone layer was sufficiently dense to absorb suns UV radiation Biological info in genetic lang. common to all organisms Genome: sum of all the DNAmolecules contained in each of its cells DNA: long sequences of four different subunits (nucleotides—sequence of four contain genetic info) Genes: specific segments of DNAthat encode the info the cell uses to create amino acids and form them into proteins Proteins govern chemical rxns within cells and form organism structure • Different types of cells (structure/function) express different parts of the genome; hemoglobin in red blood cells, digestive enzymes in gut cells • Replication process may produce mutations spontaneously; occasionally this can improve functioning of organism under environmental conditions Populations Evolve Population: group of individuals of the same type of organism (species) Evolution: acts on populations; it is the change in the genetic makeup of biological populations through time Natural Selection: different survival and reproduction among individuals in a population, accounted for much of the evolution of life • Darwin observed that offspring resembled their parents • Organisms reproduce by replicating their genomes (mutations introduced almost every time a genome is replicated) o Genetic variants from mutation change in frequency within a population, and the population is said to evolve o Any trait that confers a small increase in the probability of survival and
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