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Name _______________________________________________________________ Test Date _Fri, 9/9______ UNIT I – INTRODUCTION TO BIOLOGY I. WHAT IS “LIFE”? (pp.16-22, 35-36) A. Complexity of Life Biology is the study of _life____. To study “life” is to study a subject that is awesomely complex. Our common goal is that you _understand______ life because it is only when you understand that you can truly _learn___ . . . And as the wise Mrs. Rice says, “If you _memorize_____, you _forget______; when you _learn________, you _remember______! ☺ To accomplish this, there are two important keys: 1. Active Listening – Listening is not a passive activity! An active listener _______________________________ _______________________________ _______________________________ _______________________________ 2. Responsible Learning – A responsible learner takes care of business; that is, does what he/she needs to do to truly learn! ________________________________ ________________________________ ________________________________ ________________________________ B. Characteristics of Life 1. Living things are made of _cells___ . A cell is the _smallest unit of life____________ 2. Living things obtain and use _energy_____. Our ultimate source of energy is the _sun_____. Plants can convert the sun’s energy into useable energy in a process called _photosynthesis__________. The chemical processes that occur in an organism to convert food to _energy______ are known as _metabolism________. 3. Living things _respond to their environment____________________. Living things react to a _stimulus__________; for example, _temperature, light________________________________. 4. Living things maintain a _constant____ internal environment. This is known as _homeostasis________ or __internal harmony_______. 5. Living things _grow and develop_______. Development describes _physical changes_____________ that take place during the _lifetime_________ of an organism. 6. Living things are based on a _universal genetic code_______ - _DNA_____. 7. Living things _reproduce________. If this did not occur, _species would die out__________ 8. As a group, living things _evolve____; this means, _change over time________________. C. Hierarchy of Life 1. _Atom_____ - Smallest unit of matter that retains its elemental properties 2. _Molecule________ - Groups of atoms bonded together 3. _Cell________ - Smallest working unit of life 4. _Organism______ - Individual living thing; depending on the complexity, an organism may be composed of: a. _Tissue_________ - groups of cells working together b. _Organ________ – groups of _tissues____ working together c. _Organ system_____ - groups of _organs___ working together 5. _Population____ - Group of organisms of one _species___ in one area 6. _Community______ - Different populations that live together in a specific area 7. _Ecosystem_______ - A community and its _non-living components___________ 8. _Biosphere________ - Earth II. CHEMISTRY OF LIFE Organisms are composed of _matter_____, which is anything that takes up space and has mass. All matter is composed of _elements____, substances that cannot be broken down by chemical reactions. A. Elements – There are 92 naturally occurring elements, 25 of which are essential to life. Four elements make up 96% of living matter. They are: 1. _Carbon_____ 2. _Hydrogen___ 3. _Oxygen_____ 4. _Nitrogen______ B. Atoms – An atom is the smallest unit of _matter__ that still retains the properties of that _element_____. An atom is composed of the following _sub-atomic______ particles: Protons - __+___ charge; located _in nucleus______ Neutrons - _No___ charge; located _in nucleus_____ Electrons - _-__ charge; found _orbiting around nucleus____________ Protons and neutrons are packed together to make up a dense core, the _nucleus___, and they have approximately the same mass. Thus, the overall charge of the nucleus is _positive____. Electrons orbit around the nucleus at nearly the speed of light. Their mass is so small that they are not used when calculating _atomic mass____. It is the _charge attraction______ that holds an atom together. C. Atomic Number – This is a number unique to each element that identifies the number of _protons____ in its atoms. An atom is neutral or _uncharged_____________, therefore the number of _electrons___ = the number of _protons_______. D. Isotopes – Although all atoms of a given element have the same number of _protons_______, the number of _neutrons_______ may vary. These different forms of an atom are called _isotopes________. An example of an element that forms isotopes is _carbon_____. Carbon-12 → the most common & _stable___ form of carbon; has 6 protons and _6___ neutrons Carbon-13 → __6____ protons & __7____ neutrons Carbon-14 → __6____ protons & _8____ neutrons Some isotopes are very unstable or _radioactive_______. These isotopes are very useful in _research_________ and _medicine_____. E. Chemical Bonds & Compounds (pp. 37-38) Elements combine together in fixed ratios of atoms to form _compounds_______. Compounds are held together by _chemical bonds______________. The reactivity of an atom and the type of chemical bond that it forms are determined by the number of _electrons________ it has. 1. Ionic Bond – Weaker bond in which electrons are _transferred______- that is, one atom _strips_____ an electron(s) away from the other. Results in 2 oppositely-charged particles called _ions____ that are attracted to each other due to the difference in _charge____. Examples include _salt_____ 2. Covalent Bond– Strong chemical bond in which electrons are _shared_____________. Results in a very stable compound called a _molecule____. Examples include _water, glucose__________. F. Chemical Formula - _Description______ of a compound. Identifies the _ratio__ of _atoms_____ of elements that make up the compound. H2SO4 = _2 hydrogen atoms, 1 sulfur atom, 4 oxygen atoms _____________ Total number of atoms = _7____ C6H12O6 = _6 carbon atoms, 12 hydrogen atoms, 6 oxygen atoms _______ Total number of atoms = _24______ G. Chemical Equation – Provides the “_recipe______” for making a compound. The substances that go into the reaction are known as the _reactants_________. The substance(s) formed is known as the _product________. 2H2 + O2 2H2O Reactant = _ H2 and O2_________ Product = _ H2O______________ III. WATER (pp. 40 – 43) Water is essential for life. All organisms are composed mostly of water. A. Polarity 1. Definition of Polarity – Polarity is the unequal _sharing_____ of _electrons__ in molecules formed with covalent bonds. Water is a molecule with the chemical formula _ H2O ____. The atomic number of hydrogen is _1___ and the atomic number of oxygen is _8___. This means the O nucleus has 8 _protons__ and each H nucleus has _1__ _proton___. Due to this difference, the _oxygen__ nucleus has a much stronger positive charge than each hydrogen nucleus. Therefore, the shared _negatively__- charged electrons are much more attracted to _oxygen___. Statistically, virtually all _10__ electrons are orbiting around the oxygen end of the molecule just about all the time. Because the oxygen nucleus has _8___ protons, this gives the oxygen end of a water molecule a slight _negative__ charge and the two hydrogen ends of the water molecule a slight _positive__ charge. 2. Hydrogen “Bonds” - A hydrogen bond is not a true chemical bond because it does not result in the formation of a new _compound__. This bond is simply an _attraction__ between the slightly positivelycharged _H_-end of one _polar___ molecule and the slightly- _--___ charged end of another polar molecule. In water, hydrogen bonds form between the slightly _positively__-charged H-end and the slightly _ negatively___-charged O end. 3. Hydrophilic vs Hydrophobic – Polar molecules are attracted to other polar__ molecules, while non-polar molecules are attracted to _non-polar molecules_______. Any molecule attracted to water is described as _hydrophilic_____; molecules repelled by water are described as _hydrophobic____________. B. Properties – Polarity gives water some unique properties important in maintaining _homeostasis___ in organisms. 1. Water is "sticky" – Water molecules tend to stick together, called _cohesion___ and results in _surface tension__. Water molecules also tend to stick to other surfaces - known as _adhesion___. This explains the phenomenon known as _capillary_____ action. 2. Water is the solvent of life – Slightly-charged ends of water molecules _attract___ and _separate___ atoms that make up other compounds, thus dissolving them. Anything dissolved in water is referred to as a _solution_____. Many important compounds in cells are in solution. 3. Water has a high heat of vaporization – Perspiring cools us because it requires _heat energy____ to change water from a liquid to a _gas____. When perspiration _evaporate___, the heat required is drawn from our _skin________. 4. Water has a high specific heat – This allows large bodies of water to maintain a stable temperature. 5. Liquid water expands as it freezes – Ice is less dense than water so it floats which _protects_____ organisms and _insulates lakes, rivers, oceans____________ IV. THE IMPORTANCE OF CARBON (pp. 44-45) Although a cell is composed of 70% to 95% _water_________, most of the rest consists of carbon-based compounds. Carbon can form very large, complex molecules called _organic_____ compounds due to its number of electrons. Organic molecules important in organisms are called _biomolecules (macromolecules)____. A. Polymers - Most biomolecules are _polymers__________. The prefix “poly” means _many_____. A polymer is a large molecule composed of _many_________ identical or similar building blocks. The sub-units, or building block molecules, of a polymer are called _monomers_______. B. Dehydration Synthesis – Reaction that occurs to _covalently__________ bond two or more _molecules_____________ together. __Water______ is released as a waste product. C. Classes of Biomolecules: 1. _Carbohydrates________________ 2. _Lipids_______________________ 3. _Proteins_____________________ 4. _Nucleic Acids_________________ V. CARBOHYDRATES (p. 45-46) Carbohydrates are used for immediate and stored _energy____ and as a _building material____________. Carbohydrates contain the elements _C_, _H__, and _O___. The ratio of _H___ atoms to _O___ is _2 : 1____. In other words, for every _2 hydrogens__ in a carbohydrate, there is _1 oxygen____. There are three groups of carbohydrates: A. Monosaccharides – “_One__ Sugar”. Simplest of all sugars. Although they vary in the number of _C___ atoms that make up the molecule, the ratio of _2 H : 1 O_____ is always present. Monosaccharides are the building blocks, or _monomers______, for the more complex carbohydrates. 1. 5-carbon monosaccharides – Examples are _deoxyribose_____ and _ribose___. These two sugars are a main component of _DNA___ and _RNA____, respectively. Glucose 2. 6-carbon monosaccharides – There are three 6-carbon monosaccharides. They all have the formula, _C6 H12 O6___ and are known as _isomers____. Isomers have the same chemical formula, but the _atoms____ are arranged differently giving each molecule different properties. Glucose – Preferred _energy source__________ for most organisms, including _humans_________. Found in _honey________. Fructose - _Very sweet!______. Found in _fruit_____. Galactose – Found in _milk______ B. Disaccharides - _Two__ monosaccharides _covalently____ bonded together Sucrose - _Table sugar___________. Composed of _glu + fru____________________ Lactose - _Milk sugar_____________. Composed of _glu + galac_________________ Maltose - _Found in seeds, grains___. Composed of _glu + glu___________________ C. Polysaccharides - _Many____ monosaccharides _covalently_________bonded together. They are divided into two groups based on function _Energy Storage_______ Polysaccharides _Structural_______ Polysaccharides 1. Storage Polysaccharides – Long _polymers_____ of _glucose_________ broken down as needed for _energy_________ Glycogen – Storage form of _glucose_______ in _animals_______. In humans, most glycogen is stored in _liver______ and _muscle_____ cells. Starch - Storage form of _glucose______ in _plants________. Humans are able to break down starch for energy. 2. Structural Polysaccharides – Used as a _building material________ in many organisms Cellulose – Major component of _plant cell walls_____________. Composed of monomers of _glucose_________. Humans are unable to break the bonds in cellulose; therefore it cannot be used for _energy____ but it is still important to our diet as a source of _fiber______. Chitin - Major component of _fungi____ cell walls and the _exoskeleton______ of insects and other arthropods. VI. LIPIDS (p. 46-47) _Non-polar______ molecules that are not _soluble________ in water. Made up of _C___, _H___, and _O___, but lipids do not have the _2H : 1O______ ratio found in carbohydrates. Our bodies need lipids for _insulation, cushioning, energy storage____________________. There are 3 important groups: A. Fats & Oils – Characterized by presence of _three fatty acid tails____. Generally referred to as _fat___ if lipid is solid at room temperature and an _oil___ if lipid is liquid at room temperature. Fats and oils are classified as _saturated ___ or _unsaturated_, depending on the type of covalent bonds in the fatty acids. _Saturated ___ fats have been linked to heart disease. B. Phospholipids – Unique lipid because one end of the molecule is _non-polar____, but the other end is _polar___. Phospholipids are a part of every living _cell membrane_____. C. Steroids – An important example of a steroid is _cholesterol____. Cholesterol is found in animal _cell membranes____ and is also used to synthesize some _hormones, including testosterone_______. VII. PROTEINS (pp. 47-53) In addition to _C___, __H__, and _O___, proteins contain _N__. A. Monomers The monomers of proteins are _amino acids_____. There are _20_____ amino acids that combine together in different _numbers__, _patterns___, and _arrangements______ to form proteins. All 20 amino acids are identical, with the exception of a portion called the _R group________. The differences in the 20 amino acids are due to the differences in the make-up of the R groups. B. Protein Structure The shape of a protein is very important to its function. Its shape is determined by interactions between R groups; for example, _Covalent___________ bonds _Ionic______________ bonds _Hydrogen__________ bonds Van der Waals Forces – Similar in principal to H-bonds; intermolecular attractions between _non-polars_ C. Function Structure Transport _Hormones________ Cell Identification & Communication _Metabolism______ VIII. NUCLEIC ACIDS (p. 47) Nucleic acids are _polymers___ composed of _monomers______ called _nucleotides______________. Nucleotides contain __C___, _H__, _O____, _N__, and _P__. There are three important members of this group: Nucleotide A. DNA Composed of __2__ strands of _nucleotides_____ _covalently_____-bonded together through _dehydration synthesis_______ Twisted together to form a _double helix______ structure. Contains the _genetic code___; the _working instructions___ for a cell. B. RNA _Single___ strand of nucleotides _Carries out______ the instructions in DNA. C. ATP Single _nucleotide_____ Provides usable _energy__ for all cells