Questions for you to study from Chapter 1- Chapter 2 follows below the questions1. What are the 7 characteristics that all organisms share?Composed of cells Maintain homeostasis Respond to stimuli Use and convert materials and energy GrowthReproduceEvolve2. What are the characteristics of life that viruses lack? Name those that they have.Lack: Not cells, don’t grow, don’t acquire nutrients Have: Reproduce, 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 (prokaryotic) (single cell), Archaea (prokaryotic) (single cell), Eukarya (multicellular)They differ in size, number of cells, and the way that they gather nutrients4. How are prokaryotic cells and eukaryotic cells different. What cell structures do they both have?Both have cytoplasm and ribosomesProkaryotic cells are smaller in size, doesn’t have an enclosed nucleus , does not have have membrane bound organelles 5. Species names are made up of what part(s)? Also, put all categories in order from domain to specific epithet.Kingdom, phylum, class, order, family, genus, species 6. What are the levels of life from atoms to the biosphere?Cell, tissue, organ, organ system, multicellular organism, species, community, ecosystem, biosphere7. 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?Atoms, Molecules and Life – Chapter 2Coming up in this chapterWhat 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 particlesIn the nucleus, there are __ positively ____ charged _protons _ and uncharged _electrons_. In orbit around the nucleus are negatively charged particles called electrons.Atoms are electrically _ neutral __ because their number of protons and electrons is equal__Atomic Number__- The __ number of protons ___ in the nucleus of an atom atomic mass of an element is the total mass of its protons, neutrons, and electronsAtomic ModelsElementsAn element is a substance that cannot be broken down by ordinary chemical reactions. Have unique chemical and physical propertiesAt room temperature they can be gasses (ex: hydrogen), liquids (ex: mercury), or solids (ex: lead)There are 92 types of naturally occurring elementsThe atomic number (number of ??) is the defining value for an elementAll atoms of an element have the same atomic number For example, carbon has six??, nitrogen has sevenDiamonds and graphite are both pure carbon, but the arrangements differThese elements compose about 96% of human body weight __oxygen, hydrogen, carbon, and nitrogen These are known as the “building blocks” of life on earthIsotopesAtoms of an element _may vary in the number of neutrons_ they have in the nucleusVariant forms are called _isotopes__Some isotopes are radioactive (meaning that they spontaneously break apart, forming different atoms and releasing energy) and are used in researchRadioactivity 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 StructureElectron shellsElectrons are found in _electron shells___ around the atoms nucleusThe 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 moleculeElectron 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 levelsWhen _energy__ excites an atom, it causes a _electron to jump from a lower to higher energy shell_Later, the electron falls back into its original shell, releasing the energy (see fig. 2.3)Molecules consist of two or more atoms, from the same or different elements, that are _held together by interactions among their outermost shell_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 shellsReactions 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 fullBUT, 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 electronsReactive atoms gain stability through electron interactions (chemical reactions)1. Electrons can be lostfrom_ from outermost shell2. Electrons can be gained_ (added to outermost shell)3. Electrons can be shared with another atom when both atoms have full outermost shells1 Hydrogen atom and 2 oxygen atoms = waterHydrogen and oxygen atoms gain stability by interacting with each otherSingle electrons from each of two hydrogen molecules fill the outer shell of an oxygen atomFree radicals form when reactions cause ____molecules to have atoms with unpaired electrons _ in their outer shellsHighly reactive free radicals can damage cellsFree radicals steal electrons, destroying other moleculesCell death can occur from free radical attackCauses of free radicals- sun, x-rays, cigarette smoke, AND cellular processes that require oxygenAntioxidants intercept the harmful effects of free radicals! Ex: Vitamins C, A, E, lycopene, beta-carotene, luteinChemical bonds hold atoms together in moleculesA chemical reaction is a process by which new chemical bonds are formed or existing bonds are broken, converting one substance into another1. _Ionic Bonds__ form among charged atoms that are called ions2. _Covalent Bonds__ form between uncharged atoms that share electrons3. _Hydrogen Bonds_______ are attractive forces between polar moleculesTable 2.2 Bonds in Biological MoleculesIons and ionic bondsAtoms that have lost or gained
View Full Document
Unlocking...