Biology Biology: Exploring Life Biology is the scientific study of life

3002/els_le2.jpg Biological Hierarchy of Organization: Life can exist here

Hierarchy of Life; Organization levels Molecules are atoms held together by chemical bonds (ex: DNA, protein) Organelles are membrane-bound structures with specific functions for & w/in some cells Cells are the smallest unit of life; separates the environment with a membrane Tissues are layers of cells to perform a specific function Organs are groups of tissues working together to perform a specific function

Hierarchy of Life; Organization levels, cont’d Organ Systems are organs grouped together to perform a function Organism is a living thing within a population Population: the same species living within a specific area Community: many groups of different species within an ecosystem Ecosystem: contains biotic (living) factors & abiotic (nonliving) factors within a specified area/community Biosphere: all ecosystems of the Earth

Hierarchy of Life; Organization levels, cont’d From most specific to general: Atoms  Molecules  Organelles  Cells  Tissues  Organs  Organ Systems  Organism  Population  Community  Ecosystem  Biosphere *Blue color denotes living/biotic

Cycle of Nutrients and Energy: /current/lectures/kling/ecosystem/zebra2.gif

Organism Interaction, Matter, and Energy An Ecosystem contains 3 categories of organisms: –Producers (autotrophic organisms like plants, algae, and some bacteria): perform photosynthesis (absorb H 2 O, CO 2 & sunlight & convert these to sugar and O 2 ) –Consumers (heterotrophic organisms like animals): organisms that eat plants and other animals. These take in O 2 and release CO 2, while releasing waste into the environment. –Decomposers (heterotrophic organisms like bacteria and fungi) that break down wastes and dead/decomposing organisms, while recycling matter into the environment (which the producers use).

Organism Interaction, Matter, and Energy, Cont’d Ecosystems have 2 major processes: Recycling chemical nutrients and energy flow. Recycling chemical nutrients: O 2, CO 2, H 2 O, etc. go from the air and soil to producers to consumers to decomposers and then back to the air and soil. These are recycled! Energy Flow: solar energy is absorbed by producers & converted to chemical energy thru photosynthesis. –Chemical energy is passed thru many organisms (consumers: primary to secondary, etc) and then finally to decomposers. –At every pass, some energy is LOST as heat. –Energy flows THROUGH the ecosystem (enters as light; exits as heat).

Cells, the structural & functional unit of life The cell is the basic unit of life, the lowest level of structure at which the properties of life emerge. These correlate structure = function! The cell: –Regulates its internal environment (homeostasis) –Takes in & uses energy –Responds to its environment –Develops & maintains a complex organism –Reproduces (give rise to new cells)

Cells, the structural & functional unit of life, Cont’d Characteristics of a Cell: Enclosed in a membrane (which regulates the flow/regulation of materials in and out of the cell) Contains DNA (genetic material), cytoplasm, ribosomes 2 types of cells: Prokaryotic Cell (Kingdoms Archaebacteria and Eubacteria): bacteria; small and simple cells Eukaryotic Cell (All other Kingdoms): plants, animals, protists, and fungi. –Have organelles (functional compartments with specific functions) –Have a nucleus that contains DNA

Prokaryote: Eukaryote:

Unity of Life The continuity of life is based on ALL living things have DNA (genetic material). Genes (inheritable material) are made up of DNA sequences –DNA is 2 chains coiled together to form a double helix (structure) –Nucleotides= building blocks; these contain nitrogenous bases attached: adenine (A), thymine (T), guanine (G), or cytosine (C). All forms of life contain the same genetic code; the sequences (order) is different. This results in different genes.

Unity of Life, Cont’d – CHARACTERISTICS OF LIFE: In addition to Genes, all organisms have: Order (level of organization) Metabolism (all chemical reactions) Regulation (a.k.a. homeostasis, or control of the internal environment to sustain life) Growth (increase in size) Development (change in form) Energy processing (ability to use & transform, or transduce, energy) Response to Environment (both internal & external stimuli) Reproduction (make more like themselves) Evolutionary Adaptation (traits that are best suited to the environment that are passed on to the offspring; ie. camouflage, spots, etc)

Diversity of Life – Classification of organisms A species is the smallest category of organisms (most specific) –share the most common characteristics –can reproduce with each other. Taxonomy is the branch of Bio which names & classifies organisms according to characteristics and similarities –molecular, genetic, biochemical, morphological, evolutionary phylogenies/histories, etc. This is completed from broadest category to most specific: Domain  Kingdom  Phylum  Class  Order  Family  Genus  Species

cientific_classification.png content/uploads/2008/05/atlas-moth-scientific-classification.jpg

There are 3 Domains: Domain Bacteria or Eubacteria, Domain Archaea, Domain Eukarya Domain Bacteria or Eubacteria (have peptidoglycan in their cell walls) Domain Archaea (live in extreme environments, like hot or salty places, or anaerobic environments) –BOTH Bacteria and Archaea are prokaryotic, are bacteria, are unicellular & microscopic, and are found in Kingdoms Archaebacteria and Eubacteria. Domain Eukarya –Include all eukaryotic organisms (have organelles & a nucleus). –Include protists (Kingdom Protista). These are uni or multicellular. Ex. Include algae and protozoans –Include plants (Kingdom Plantae), which have a rigid cell wall and perform photosynthesis. –Include animals (Kingdom Animalia) which lack a cell wall and must consume food –Include fungi (Kingdom Fungi) which are yeast, mushrooms and molds that decompose dead organisms. –Protista, Plantae, and Fungi are generally separated by their modes of nutrition.

Domain Bacteria: Electron Micrograph of E. Coli teria_e_coli.jpg Domain Arachaea: Image of Methanococcus jannaschii n100/images/dmethanopyrus.jpg

files/Bio%20102/Bio%20102%20lectures/Evolution,%20 Speciation,%20Taxonomy/specia12.gif A Micrograph of Euglena (Protist): images/biol_04_img0381.jpg Plant: Palm Tree ng.org/palm_tree_2.jpg Fungi: Death Cap, Death Angel Mushroom mg/toxics/farinera_borda1.gif Animal: Bull Shark files/NGS/Shared/StaticFiles/animals/image s/primary/bull-shark.jpg

Evolution Explains the Unity & Diversity of Life Darwin wrote On the Origin of Species by Means of Natural Selection which supported the idea of evolution = species alive today are descendants of ancestral species (a.k.a. ‘descent with modification’). This means descent from a common ancestor. This supports the unity of life. Darwin’s idea supported the diversity of life (modification as species diverged). darwin/Darwin_age29.JPG

Darwin recognized that variations existed within organisms. –These enhance their ability to survive AND reproduce (this is the essence of evolution by means of natural selection). These successful adaptations are the result of evolution, the process of change over time which has transformed life on Earth.

Evolution Explains the Unity & Diversity of Life, Cont’d Darwin proposed that evolution occurred through Natural Selection (NS): –Recognized (observed) that w/in a population, variations exist AND in many cases more organisms were produced than could survive (to produce their own offspring); this was an overproduction of offspring. –From these observations, he suggested that the individuals who were likely to survive AND reproduce were best suited to the environment; they inherited the best traits and would pass these traits on to their offspring. –Overtime, the best suited (or favorable) traits would accumulate within a population. This could eventually lead to a new species.

Evolution Explains the Unity & Diversity of Life, Cont’d The environment ‘selects’ for individuals w/certain traits meaning there is an unequal reproductive success. This is Natural Selection (NS). The product of NS = evolutionary adaptation, or the accumulation of favorable traits in a population over time. NS is an editing process that works on heritable variations which are exposed to environmental factors that favor reproductive success. Major alteration of a species could occur from many small changes w/in a population. Darwin proposed that a new species could arise due to these gradual changes over long periods of time.

Scientific Method – terms that have different meanings in Science versus mainstream use: Science means “to know.” “Science can neither prove nor disprove the existence of a God or supernatural power- for such questions are outside the bounds of science.” A hypothesis is a possible (plausible) explanation based on observation (that can be tested). Mainstream use : an “educated guess” Theories in science: A theory is a hypothesis that has been tested repeatedly and is generally regarded as true. Examples: Theory of Evolution, Theory of Relativity, Atomic Theory, Cell Theory. Mainstream use: just an “idea”

The Evolution Connection Evolution is the CORE theme in biology. There are many differences (and similarities) in DNA among individuals, populations, and species; this reflects evolutionary change. Through the Human Genome Project (HGP), scientists have been able to ID & construct the DNA base sequences of many species. –allows comparative & functional genomics (the ability to identify common genes, search for new medical treatments, and more using DNA technology). DNA differences in humans is used in forensics: this is DNA fingerprinting or DNA profiling and is used to convict or exonerate, determine paternity, or identify remains.

Evolutionary knowledge can help scientists in the understanding: Vaccinations HIV drugs virus evolution the development of antibiotic-resistant bacteria & pesticide-resistant crops how to help endangered species