Themes in the Study of Life 09 10 2013 Evolution the process of change that has transformed life on earth from the earliest beginnings to the diverse organisms living today Theme New properties emerge at each level in biological hierarchy Emergent properties properties that emerge at each step that weren t there at the preceding level o Due to arrangement and interactions of parts as complexity increases Reductionism the approach of reducing complex systems to simpler components that are more manageable to study Systems biology an approach that attempts to model the dynamic behavior of whole biological systems based on a study of the interactions among the systems parts o Used to answer large scale questions Levels of biological organization o Biosphere o Ecosystems o Communities o Populations o Organisms o Organs and Organ Systems o Tissues o Cells o Organelles o Molecules Theme Organisms interact with other organisms and the physical environment Global climate change global warming risen 1 degree C since 1990 3 degree C over he 21st century Theme Life requires energy transfer transformation Chlorophyll sunlight photosynthesis Animal muscle sugar to fuel movement Theme Structure and function are correlated at all levels of biological Form fits function analyzing structure gives clues on what it does organization and vice versa Cells Theme The cell is an organism s basic unit of structure and function o Prokaryotic bacteria and archaea DNA not separated o Eukaryotic all other forms of life including plants and animals Sub divided into various membrane enclosed organelles Theme The continuity of life based on heritable info in form of DNA DNA 2 long strands in double helix o Central database o 4 nucleotides A T C G o specific sequential arrangements of these encode gene info Human proteins growth muscle cell antibodies enzymes RNA intermediary sequence of nucleotides transcribed specific protein o Regulates the function of protein coding genes Gene expression the process by which the info in a gene directs the production of a cellular product Difference between organisms reflect differences in nucleotide sequence rather than genetic codes Genome the entire library of genetic instructions an organism inherits Genes for about 75 000 kinds of proteins Genomics study of whole sets of genes of a species as well as comparing them Bioinformatics use of computational tools to store organize analyze the data that results from high throughput methods Theme feedback mechanisms regulate biological systems Negative feedback accumulation of an end product of a process slows that process most common form of regulation in living systems Positive feedback end product speeds up its own production Core theme evolution accounts for the unity and diversity of life Diversity 1 8 million species est total 10 100 million 3 domains Bacteria Archaea Eukarya plantal fungi animalia Protists single cell euk November 1859 Charles Darwin on the origin of species by natural o Descent with modification contemporary species arose from selection Darwinism a succession of ancestors o Natural Selection Individuals in a population vary in their traits many of which seemed to be heritable More offspring than can survive to produce more offspring competition arose Species are generally adapted to their environments Experiments based on logic Inductive reasoning observations lead to important conclusions Deductive reasoning reasoning after hypothesis from general to specific if then logic Scientific theory much broader than a hypothesis General enough to spin off many new hypotheses than can be tested Supported by more evidence Sometimes get modified or rejected Model organism a species that is easy to grow in a lab and lends itself particularly well to the questions being investigated The Chemical Context of Life 09 10 2013 Organisms are composed of matter Anything that takes up space and has mass Element Compound ratio substance that cannot be broken down to other substances by chemical reactions 92 in nature Substance consisting of 2 different elements combined in a fixed Has characteristics different from its elements 20 25 of the 92 elements are essential to living organisms humans need 25 plants need 17 O C H N 96 of living matter Ca P K S and more 4 Trace elements required by an organism in only minute quantities Thyroid needs 15mg of iodine goiter iodine deficiency Atom smallest unit of matter that still retains the properties of an element Subatomic particles neutrons protons electrons Dalton measurement atomic mass unit P N close to 1 Dalton electron 1 2000 of a proton Isotopes different atomic forms of same element Atomic mass is average of all the element s naturally occurring Radioactive isotope nucleus decays spontaneously giving off isotopes particles and energy o When carbon decays it becomes nitrogen o Helpful with medicine tracers and PET scans Energy capacity to cause change by doing work Potential energy energy that matter possesses because of its location or structure Chemical behavior depends mostly on the number of electrons in the outermost shell Chemical bonds Valence electrons in valence shell Inert chemically unreactive completed valence shell Covalent bond sharing of a pair of valence electrons by 2 atoms Bonding capacity Valence Oxygen has a valence of 2 Electronegativity attraction of a particular atom for the electrons of Non polar covalent bond same electronegativity H2 and O2 Polar covalent bond one atom bonded to a more electronegative a covalent bond atom H2O Ionic bond cations and anions attract each other o Ionic compounds or salts NaCl Hydrogen Bond very important o Partial charge on H that is covalently bonded to an electronegative atom allows H to be attracted to a different electronegative atom nearby Van der Waals interactions individually weak and occur when molecules are very close together o Ever changing regions of and charge enable molecules to stick to one another o Can be powerful together VDW HB IB and other weak bonds may form between parts of a large molecule like a protein o Reinforce the 3D shape of the molecule Molecular Shape Function Shape is important to function in living cell Form dictates function Determines how biological molecules recognize and respond to each other with specificity Molecular Specificity Ex Opiates Endorphins Opiates are derived from opium 1800 s opium morphine derived heroin synthesized Class of chemicals called endorphins 1975 o Signaling
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