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Midterm Review.pdf

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Health Sciences
HSCI 100
Mark Lechner

HSCI100 Human BiologySpring 2014HUMAN BIOLOGYHSCI 100Spring 2014An Outline and Synopsis of Conceptsfor ExamIScienceScience is a system of generating and organizing knowledge about the universeIt is a system that is testable and undergoing constant revisionBiologists use the scientific process when they study the natural worldA hypothesis is formulated and tested to arrive at a conclusionData and observations are collected and analyzed in the formation of conclusionsHypotheses theories or models in science are never proven they are just supported or rejectedIf rejected then alternative hypotheses need to be developed and testedThe scientific method uses controls to evaluate outcomes from experiments or studies andfrequently looks at correlations through the use of independent and dependent variablesThe scientific method may yield error technical or otherwise and is prone to biasLife and BiologyBiology is the study of living things and their interactionsThe ultimate biological goal is reproductionSuccessful organisms achieve this in changing environments that may pose complex challengesThe biological solutions may be thought of as adaptations Living things are organized they acquire materials and energy they reproduce grow anddevelop they are homeostatic they respond to stimuli and they have an evolutionary historyThis last property indicates that all living things are related to one anotherThe cell is the smallest unit of life and all living things are made of cellsOrganization of matter into lifendAccording to the 2 law of thermodynamics in a closed system the tendency is for entropy chaos or disorder to increase and matter and energy to go to equilibriumHowever living organisms strive to maintain order and avoid true equilibriumTo do this they need a constant input of energy and the inefficiency of this effort releases some energy as heat which actually increases the entropy of the system as a whole and thus ndthere is no violation of the 2 lawMatter is arranged into increasingly complex forms through a series of organizational levelsEach level has novel properties that are not predicted based on the properties of the units in the underlying level from which it was built and these we call emergent propertiesI tend to call emergent properties and adaptations good tricks they are successful arrangements of their constituent parts1HSCI100 Human BiologySpring 2014It is not known exactly how the abiotic chemicals came together to originate life or the first cell but most theories suggest that a series of chemical reactions led to production ofkey organic molecules mostly carbonbased molecules that became concentrated in lipid vesicles spheres that were the forerunners of living cells protocellsAtoms are arranged together into molecules by chemical bondsCovalent bonds are the strongest and most common bonds among biological molecules and are formed by atoms sharing electronsIonic bonds take place when atoms donate and accept electrons and the charged molecules are known as ionsHydrogen bonds are another important bond that holds many biological atoms and molecules togetherHydrogen bonds are the weakest of these three bondsWaterHOis a key molecule in living organisms and its partial polarity allows it to 2participate widely in hydrogen bondingThe pH of water and waterbased solutions is due to the concentration of H ions aka protonsAcids release protonsOn the pH scale 114 low numbers indicate acidic conditions with relatively high concentrations of protons and high numbers on the pH scale reveal basic or alkaline conditions with low concentration of protons and higher concentrations of the counterion OHLiving things like to be right in or near the middle of the range at pH7 This middle value of 7is often referred to as neutral pHBuffers help to accept excess Hor OH and keep pH near neutralMacromoleculesMacromolecules perform major functions for cellsFour main classes are found carbohydrates lipids proteins and nucleic acids though many molecules are combinations of these classesOf the four the lipid class is not based on building polymers from monomeric subunitsA principle for the role of these and other moleculesis form follows functionCarbohydrates are used as mainly as a source of energyTheir names typically have osesuffix eg glucose lactoseThey are based on 5 or 6 carbon ringed structures with a stoichiometry ratio of CHO of 121Simple sugars include monosaccharides and disaccharides but more complex polymers may be builtPolysaccharidestwo subunits are complex carbohydrates that are used to store energy for laterIn humans the common form is glycogen and in plants it is starchLipids are also a class of molecules frequently used for energyThey also have key functions in forming cell membranes and some forms are used to make hormonesTheir fundamental property is that they are mostly nonpolar and do not dissolve in water ie they are hydrophobic Lipids include fats and oilsA common structure is based on a glycerol backbone and fatty acid tailsSome parts of lipids may have a polar group and this endows this part of the molecule with hydrophilicity water lovingIf so such a lipid molecule is amphipathicdual character hydrophobic and hydrophilicExamples include the polar head groups on phospholipidsPhospholipids are the main components of cell and subcellular membranesCholesterol is a steroid class of lipid and is also a keycomponent of animal cell membranesCholesterol is used to make steroid hormones like2
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