Biology Chapter 1 Bio Life Logy the study of August 30 2013 What distinguishes something that s living from something that isn t In order to be an organism Be composed of cells Maintain Homeostasis Respond to stimuli Use and convert materials and energy grow evolve reproduce Living organisms maintain homeostasis Homeostasis to stay the same Enables organisms to cope with changes in their environment Living organisms respond to stimuli Internal and External Ex plants grow towards the source of light Ex your body can detect low blood sugar External Stimuli Light sound touch chemicals etc Internal stimuli temperature pain chemicals etc Living organisms acquire and use materials and energy Photosynthetic organisms capture energy Energy comes from the sun then photosynthetic energy uses the sun s energy then organisms eat the photosynthetic energy then organisms eat the other organisms Energy is also lost through heat Nutrients are never lost Living organisms reproduce Reproductive process differs between organisms end result is the same Parent s genes are passed on in the new organism Living organisms evolve Process of natural Selection The process by which organisms with specific adaptations reproduce more successfully than others Three major categories or domains Bacteria Archaea Eukarya Kingdom Phylum Class Order Family Genus Species Homosapiens Binomial Nomenclature Made up of genus and species Prokaryotic Bacteria and Archea NO ENCLOSED NUCLEUS Smaller in size NO MEMBRANE BOUND ORGANELLES Eukaryotic Only Eukarya Membrane enclosed nucleus larger in size Membrane bound organelles Unicellular composed of single cells All domains have unicellular organisms Multicellular Composed of many cells only eukaryotic organisms are multicellular no prokaryotic organisms Autotrophic Photosynthetic organisms all domains have photosynthetic organisms Heterotrophic Absorption of food molecules ingestion of food all domains have heterotrophic organisms as well Alex Must Count Tacos Only On Saturdays Maybe On Sundays Cuz Everyone Burps Atoms molecules cells tissues organs organ systems multicellular organisms species community ecosystem biosphere Each level is a building block for the next i Example o Mud Brick Wall Building Element a combination of multiple atoms that are the same The Scientific Method Observe question hypothesis predication Hypothesis An educated guess Theory a well tested accepted answer to a question It is possible for theories to be disproved Law Absolutely proven Very rare in biology Biology Chapter 2 August 30 2013 Elements pure chemical substance that cannot be broken into other substances by chemical reactions Composed of atoms Have unique chemical and physical properties Based on the number and configuration of subatomic particles Can be gasses liquids or solids They can either want to react with another atom or not Reactive or inert Oxygen carbon hydrogen and nitrogen compose about 96 of human body weight and are the four most common elements A single atom of a particular element has all of the properties of that element Ex Carbon can combine with other elements to form different things o Diamonds o Carbon dioxide An atom of carbon is an atom of carbon no matter what Atom The smallest unit of matter that still retains all properties of a given element Made of subatomic particles Protons neutrons and electrons Atomic nuclei provide stability Electrons can capture and release energy and can form chemical bonds Atomic number the number of protons in the atomic nucleus Atomic number is constant for a given element Atomic mass the total mass of protons and neutrons Electrons are negligible Atoms of particular elements may have different numbers of neutrons This forms isotopes Isotopes have different atomic masses Some isotopes are unstable RADIOACTIVE Radioactivity in every day life PET scan Subject is given the sugar glucose with a radioactive isotope of fluorine attached They help locate tumors in the brain because tumors use a lot of glucose and so they come off as a hot spot of radioactivity Electron orbitals are the three dimensional space around the nucleus of an atom where an electron will be found 90 of the time They are arranged into electron shells based on their energy level Electron shell restricted 3D space within which electrons orbit the atomic nucleus The first electron shell 2 electrons The second shell 8 electrons Electron shells closest to the nucleus are filled first Atoms want to have a filled outermost shell Valence Shell Electrons absorb and release energy Electricity flows through the filament causing heat Heat bumps electrons into higher energy electron shells As electrons fall back to their original shells they release energy as light Atoms can interact to form molecules Reactive an atom with a partially full valence electron shell o Oxygen o Hydrogen o Helium Inert an atom with a full valence electron shell Reactive atoms gain stability by o Losing electrons emptying valence o Gaining electrons filling valence o Sharing electrons with another atom Molecules two or more atoms held together by interaction among their valence electrons Compound a molecule composed of different types of atoms o Ex Hydrogen gas Element o Ex Water Compound Chemical Bonds Hold atoms in molecules Arise from interactions between atoms as they o Gain electrons o Lose electrons o Share electrons 3 Major Types o Ionic Bond o Covalent Bon Nonpolar Polar o Hydrogen bond Ionic bonds Electrical attraction between negatively and positively charged ions o ex Table salt Ionic compounds are called salts They are strong in crystal form but break easily in water Dissolve o Cation positively charged atom or molecule they re Pawsitive like cats o Anion negatively charged atom or molecule Covalent bonds Atoms share electrons to complete their valence shell o Hydrogen bonding is nonpolar o Hydrogen and oxygen bonding make a polar molecule Used by most biological molecules Covalent bonds o More stable in watery environments Like cells o Proteins sugars and fats all use covalent bonds Hydrogen Bonds Occur between polar molecules They DO NOT involve electron sharing They are weak but important about 20 times easier to break than a covalent bond Can form between separate polar molecules or between polar regions of the same large molecule o Ex Hydrogen bonds between water molecules o Ex Hydrogen bonds between two strand in a DNA molecule Water and life Cells are 70 95 water Water covers 70 of
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