Cell Structure and Function
Cell Structure and Function BIOL 213
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This 38 page Class Notes was uploaded by Beatrice Deckow I on Monday September 28, 2015. The Class Notes belongs to BIOL 213 at George Mason University taught by Charles Madden in Summer 2015. Since its upload, it has received 40 views. For similar materials see Cell structure and function in Biology at George Mason University.
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Date Created: 09/28/15
Studying Life quotAah there s nothing more exciting than science You get all the fun of sitting still being quiet writing down numbers paying attention yes science has it all quot if Principal Skinner 11 What is Biology Biology the scienti c study of living things Characteristics of living organisms Consist of one or more cells Contain qenetic information Use qenetic information to reproduce themselves 11 What is Biology Characteristics of living organisms They have a metabolism Can convert molecules from their environment into new biological molecules They interact with their environment Extract energy from the environment and use it to do biological work harvest energy and pollute 11 What is Biology Characteristics of living organisms They evolve Living systems evolve through differential survival and reproduction The processes of evolution have generated the enormous diversity of life on Earth Evolution a central theme of biology All living things die We 11 hope for an exception in your case though Thouhts about old men With beards Charles Darwin Allah Brahma Coatlique God amp Alfred wallace Jehovah Unkulunkulu Yahweh 1859 Etc 11 What is Biology Unicellular organisms a single cell carries out all the functions of life Multicellular organisms made of many cells that are specialized for different functions The study of cells was made possible by the invention of microscopes Robert Hooke in the 1600s described repeating units of plant material as cells 11 What is Biology Cell Theory Cells are the basic structural and physiological units of all living organisms Cells are both distinct entities and building blocks of more complex organisms Schleiden and Schwann 1838 11 What is Biology Cell Theory All cells come from preexisting cells All cells are similar in chemical composition Most of the chemical reactions of life occur within cells Complete sets of genetic information are replicated and passed on during cell division 11 What is Biology Multicellular organisms have an internal environment that is not cellular Their cells are specialized or differentiated and organized into tissues tissues are organized into organs Organ systems are groups of organs with interrelated functions Figure 16 Biology ls Studied at Many Levels of Organization Atoms Molecule Cell neuron Organ brain Organism fish 99 16 201VSlnauetA5mcialeanc 11 What is Biology Genome sum total of all the DNA in a cell DNA the information that is passed from parent to daughter cells All cells in a multicellular organism have the same genome 11 What is Biology DNA consists of repeating subunits called nucleotides Gene a specific segment of DNA that contains information for making a protein Mutations are alterations in the nucleotide sequence Figure 14 DNA Is Life s Blueprint One nucleotide fg 99 1 4 201VSinaueIA5mcialeanc 11 What is Biology Organisms acquire nutrients from their environment Nutrients supply energy and materials for biochemical reactions Some reactions break nutrient molecules into smaller units releasing energy for work 11 What is Biology Examples of cellular work Movement of molecules or the whole organism Synthesis building new complex molecules from smaller chemical units Electrical work of information processing in nervous systems 11 What is Biology Metabolism or metabolic rate the sum total of all chemical transformations and other work done in all the cells of an organism The reactions are integrally linked the products of one are the raw materials of the next 11 What is Biology Living organisms also interact Populations are groups of individuals of the same species that interact with one another A community consists of populations of all the species that live in the same area and interact Communities plus their abiotic environment constitute an ecosystem 12 How Is All Life on Earth Related All species on Earth share a common ancestor they are genetically related Earth formed 46 to 45 billion years ago but it was 600 million years or more before life evolved The history of Earth can be pictured as a 30day month Figure 18 Life s Calendar Origin of life 27w gf m 28 gym mm Flrammle 3 0 Ahma 0F lnsectaabund39ant Hm mme plam aqmtlcme Emu Eleao mammals animale First mammle Dinosaumalamlnanl 7 leil t hamlrllds 93 1 8 2KJH SlnauerAssncialeanm 12 How Is All Life on Earth Related Life arose by chemical evolution Molecules that could reproduce themselves were critical Biological molecules were then enclosed in membranes forming cells Cellbased Life is greater than the sum of it s parts This concept is called Emergence 12 How Is All Life on Earth Related For 2 billion years life consisted of single cells called prokaryotes These cells were in the oceans protected from UV radiation There was little or no oxygen 02 in the atmosphere and hence no protective ozone O3 layer The biosphere was a reducing environment 12 How Is All Life on Earth Related Photosynthesis evolved about 25 billion years ago Consequences of photosynthesis 02 accumulated in the atmosphere Biosphere became oxidizing Aerobic metabolism began Ozone layer formed which allowed organisms to live on land 12 How Is All Life on Earth Related Eukaryotic cells evolved from prokaryotes These cells have intracellular compartments called organelles with specialized cellular functions Eukaryotic cells have a membrane enclosed nucleus The nucleus contains the genetic information 12 How Is All Life on Earth Related Some organelles probably originated by endosymbiosis when cells ingested smaller cells Mitochondria generate cell s energy and chloroplasts conduct photosynthesis could have originated when prokaryotes were ingested by larger cells giving rise to modern eukaryotes 4 kr a f 1 39 l39 I life probably had a lastuniversal common ancestor i39 r s a I a quotf I jf39 h a Erin l T 1 1 a quotv Pquot I l 4 quot 1 39 H 39 I 3 394 Ejbactoia remazl 39 P Li M n 2 x J 39 l v A T Pl I It VJ Life on Earth LUCA was probably an RNAbased rather than DNA life form with extensive amounts of horizontal genetic transmission viral infection between cells The evolution of a reverse transcriptase or transposonlike activities may have converted the RNA based LUCA into DNAbased cell typesat least 3 of which survive today DNA sequence and metabolic pathways can vary from one individual to the next and from species to species but the structures and mechanisms involved remain the same t sauna 4 EN and 4 L 397 a quota w I 7 4 Uta gd dxig gitCiel 2 12 How Is All Life on Earth Related Multicellular organisms arose about 1 billion years ago Cellular specialization Cells became specialized to perform certain functions 12 How Is All Life on Earth Related Evolution results in speciation Each species has a distinct scientific name a binomial Genus name Species name Example Homo sapiens Levels of Biological Organization What kinds of organisms are there 0 Prokaryotes simple single celled no nucleus Archaea extremophiles Bacteria most bacteria 0 Eukaryotes complex many cells nucleated Protistans Fungi v Plants Animals Levels of Biological Organization Domain Kingdom Phylum Class Order Family Genus Species I Live on Earth First name is genus Escherichia coli Second name is species Drosophila melanogaster Devised by C arl Linnaeus 17071778 Homo sapiens 12 How Is All Life on Earth Related An evolutionary tree phylogenetic tree illustrates the order in which populations split and eventually evolved into new species Systematists study the evolution and classification of organisms using the fossil record and molecular evidence Figure 110 The Tree of Life Number of known Estimated total described number of living Species species 10000 Millions 260 1009 5 1rn hon Life S 2 400000 8 Plants 27039000 500000 339 m 0 9 a w 39 3 Protists n Protists V Protists gt 80 000 50000 39 1 million Protists Protists 10 million 1300000 Animals 100 million 98000 1 2 million Fungi 99 1 1 O 201i Sinauer Associates Inc 13 How Do Biologists Investigate Life Biologists use many methods to expand our understanding of life Observation improved by new technologies Experimentation 13 How Do Biologists Investigate Life The scientific method hypothesis prediction H P method Observations Questions Hypotheses Predictions Testing The Scientific Met Figure 11 Giulcid 99 1 12 9201 SinauerAssociateanc 13 How Do Biologists Investigate Life Inductive logic leads to tentative answers or explanations called hypotheses Deductive logic is used to make predictions Experiments are designed to test the predictions 13 How Do Biologists Investigate Life Controlled experiments manipulate the variable that is predicted to cause differences between groups The variable is manipulated in an experimental group and the results compared with data from an unmanipulated control group 13 How Do Biologists Investigate Life Comparative experiments look for differences between samples or groups The variables can not be controlled data are gathered from different sample groups and compared
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