Important Things from Chapter 1 Prokaryotic Eukaryotic o Evolved before Eukaryotic o Do not have nucleus o Genetic material resides in cytoplasm o Lack membrane bound organelles o Bacteria and Archaea o True membrane enclosed nucleus o Larger o Contain a variety of other organelles Bacteria Archaea o Unicellular o Auto Self Feeding or Heterotrophic Other Feeding Fungi Multicellular Heterotrophic Plantae Multicellular Autotrophic Animalia Multicellular Heterotrophic Protists Uni Multicellular Auto or Heterotrophic 1 What are the 7 characteristics that all organisms share Composed of cells maintain homeostasis respond to stimuli use and convert materials and energy grow reproduce and evolve 2 What are the characteristics of life that viruses lack Name those that they have They don t grow aren t made of cells don t require nucleus Reproduce and evolve 3 What are the 3 domains of life How are they different similar Single celled and or multicellular organisms heterotrophs autotrophs prokaryotic eukaryotic Bacteria single celled archaea single cell and eukarya multicellular 4 How are prokaryotic cells and eukaryotic cells different What cell structures do they both have specific epithet Pro has no nucleus and is smaller Euk has nucleus and is larger 5 Species names are made up of what part s Also put all categories in order from domain to 6 What are the levels of life from atoms to the biosphere 7 What is the purpose of the scientific method What are the parts of the scientific method What are variables 8 How are hypotheses different from theories Chapter 2 Atoms Molecules and Life Part 1 What Are Atoms How Do Atoms Interact to Form Molecules Why is Water So Important to Life Atoms are the fundamental structural units of matter and are composed of three types of particles In the nucleus there are positively charged protons and uncharged neutrons In orbit around the nucleus are negatively charged particles called electrons Atoms are electrically neutral because their number of protons and electrons is equal The in the nucleus of an atom atomic mass of an element is the total mass of its protons neutrons and electrons Atomic Models Elements An element is a substance that cannot be broken down by ordinary chemical reactions Have unique chemical and physical properties At room temperature they can be gasses ex hydrogen liquids ex mercury or solids ex lead There are 92 types of naturally occurring elements The atomic number number of is the defining value for an element All atoms of an element have the same atomic number For example carbon has six nitrogen has seven Diamonds and graphite are both pure carbon but the arrangements differ These elements compose about 96 of human body weight oxygen carbon hydrogen and nitrogen These are known as the building blocks of life on earth Isotopes Atoms of an element may vary in the number of neutrons they have in the nucleus Variant forms are called isotopes Some isotopes are radioactive meaning that they spontaneously break apart forming different atoms and releasing energy and are used in research not radioactive carbon 12 13 Radioactivity in research positron emission tomography PET scan Subject is given the sugar glucose with a radioactive isotope of fluorine attached tumor cells use large amounts of glucose so radioactivity is highest there Author Animation Atomic Structure Hydrogen isotopes Deutrtium Electron shells Electrons are found in electron shells around the atoms nucleus The first shell or energy level holds two electrons Subsequent shells holds up to eight While the nucleus provides stability the electrons interact with other atoms for example to form chemical bonds Chemical bonds are the force of attraction between atoms that holds them together within a molecule Electron shell restricted 3D spaces within which electrons orbit the atomic nucleus Fig 2 2 Life depends on electrons capturing and releasing energy Electron shells correspond to energy levels When energy excites an atom it causes an electron to jump from a lower to a higher energy shell Later the electron falls back into its original shell releasing the energy see fig 2 3 Electrons can absorb and release energy Electricity flows though filament causing heat Heat bumps electrons into higher energy electron shells As electrons fall back to their original shells they release energy as light Molecules consist of two or more atoms from the same or different elements that are held together by interactions among their outermost electron shells A substance made of atoms of different elements is a compound Reactions between atoms depend upon the configuration of electrons in the outermost electron shell Atoms interact when there are vacancies in the outermost electron shells Reactions that fill or empty outer electron shells produce stable chemical bonds coming up If the outermost shell is completely empty or full atoms will not react with other atoms considered inert Example Neon eight electrons in its outermost shell is full BUT atoms will react with other atoms if the outermost shell is partially full considered reactive Example Oxygen six electrons in its outermost shell can hold two more electrons Reactive atoms gain stability through electron interactions chemical reactions 1 Electrons can be lost from outermost shell 2 Electrons can be gained added to outermost shell 3 Electrons can be shared with another atom when both atoms have full outermost shells 1 Hydrogen atom and 2 oxygen atoms water Hydrogen and oxygen atoms gain stability by interacting with each other Single electrons from each of two hydrogen molecules fill the outer shell of an oxygen atom Free radicals form when reactions cause molecules to have atoms with unpaired electrons in their outer shells Highly reactive free radicals can damage cells Free radicals steal or donate electrons destroying other molecules Cell death can occur and lead to heart disease and Alzheimer s from free radical attack Cause of free radicals sun x rays cigarette smoke and cellular processes that require oxygen Antioxidants vitamin C A E lycopene beat carotene lutein Chemical bonds hold atoms together in molecules A chemical reaction is a process by which new chemical bonds are formed or existing bonds are broken converting one substance into another 1 Ionic bonds form among charged atoms that are called ions 2 Covalent bonds form between uncharged atoms that share electrons nonpolar equal polar unequal 3 Hydrogen bonds are attractive
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