what is a model (in a scientific sense)?
Click the card to flip 👆
1 / 211
Terms in this set (211)
validityis the extent to which a measure reflects or assesses what a researcher is trying to measure.importance of replication in an experiment-because in all biological systems there is variation -the response of a dependent variable to differences in the independent variable cannot always be expected to be the same even under identical conditions. this is why scientists repeat experiments to determine whether the results are consistent. REPLICATION of an experiment increases our confidence in the results and gives us an idea of how much variation there is in the response to the independent variable.Steps in Hypothesis Testing1. observation 2. question 3. hypothesis 4. prediction 5. experimentation 6. data collection 7. examining and evaluating the data 8. rejection or support of the hypothesis(1) observationobserve something in the world around you(2) questionformulate question why or how regarding observation(3) hypothesiseducated guess or tentative explanation statement null=no effect alternative=there is an effect(4) predictionwhat you expect to see if alternative hypothesis is correct -if, then statement(5) experimental designvariables: independent (PREDICTOR)-what you are manipulating dependent (RESPONSE) variable- what you are measuring standardized variable- what you are keeping constant or trying to control experimental treatments- different levels of the independent variable control treatment- without independent variable- OR- constant level of independent variable all treatment groups subject to same conditions, only change independent variable replication- repeat to eliminate random variation -allows to isolate variation due to independent variable(6) Evaluate ResultsWas your hypothesis supported or rejected?(7) Future Researchgenerate new question based on results of previous researchreaction timetime between stimulus and response to stimulusscience is a self correcting process STRENGTHscience is performed by humans and reflects the values of the individuals involved WEAKNESSexperimental treatmentsare treatments subjected to manipulation of the variable of interestcontrol treatmentindependent variable is either eliminated or set at a standard valuevalues set for the independent variable are called thelevels of treatmentreplicationallows you to eliminate random variation -isolate variationstandard deviationa measure of how much variability there is around the mean small number= little large number= a lotwhat is the main difference between a compound microscope and a dissecting microscope?compound-light: an enlarged image of the object observed dissecting: 3D imagethe largest cell/ longest cell =a neuron or nerve cell in a giraffe, four meters longcells can be grouped into two major categoriescells of bacteria and archaea are PROkaryotic -small (0.2-5 micrometers) -lack a true nucleus and other membrane- bound organelles EUkaryotic cells tend to be -larger (10-100 micrometers long) -have a true nucleus (where DNA is stored and organized into chromosomes) and other membrane bound organellesall cells at least one point in their livescontain one or more molecules of DNA all cells contain -a semi-permeable plasma membrane (surrounds the cell) -ribosomes (protein production) -cytoplasm (between plasma membrane and nucleus)light microscope Uses refraction of light to enlarge image with lens Dissecting and Compound 4X-1000X magnificationmicroscope that uses a beam of light passing through one or more lenses to magnify an object relies on the bending or refraction of visible wavelengths of light to form an enlarged image of the object observed Galileo Galilei 1600s - eyes of insects magnify up to 1000 times higher the magnification, lower the resolutioncellulaesmall roomselectron microscope Uses electron beam to produce image 10,000,000X magnificationa microscope that focuses a beam of electrons to magnify objects -which uses electrons to form an image of the specimen -magnify up to 1 million times -allowing observation of fine structure of cellsDissecting microscope (Stereo microscope) -two eye pieces allow one to see in three dimensions (3D) -working with small but visible items -fingerprints and small animalslight microscope used for low magnifications and larger objects research tool for viewing larger specimens under magnification magnification- 2x-40x (Use for small but visible objects)compound light microscopean instrument that magnifies small objects so that they can be seen easily by using two or more lenses magnification- 40x-1000x (2D image and specimen) Use for thin and invisible objects; organellesparts of a dissecting microscopestage ocular lenses and eyepiece direct light source incidental light source focus knob magnification knoba ridgeraised part of fingerprintfurrowrecessed part of fingerprintloopridges appear to enter from one side, loop around, and exit from THE SAME SIDEarchridges appear to enter from one side of the finger, form a small peak, and exit the OPPOSITE side of the fingerwhorlridges in the center do not enter or exit but form a closed circlebasesupports the microscopebody tube and adjustment knobs aresupported by the armlampis used to send light through the hole in the stage to illuminate the specimenthe stageholds the slide over a hole that admits light from the lampiris diaphragmbelow the condenser. -vary the light passing through the specimen -more light at higher magnificationrotatable nosepiece-4 objectives of different magnifications 1. 4x 2. 10x 3. 40x 4. 100xeyepieceupper lens through which you will look to observe a specimencoarse adjustment knobMoves the stage up and down for focusing -move the objective to approx. the desired distanceFine course-adjustment knobraises or lowers the objective lens very slightly -exact focuselectron microscopeatoms, small molecules, lipids, proteins, ribosomes, viruses, mitochondria, most bacteria, nucleuslight microscope LMnucleus, eukaryotic cells, frog eggdissecting microscope DMfrog eggplant cellscell wall composed of cellulose in addition to a cell membrane -boxy appearance -large central fluid filled vacuole -chloroplast (green organelles of photosynthesis) -nucleusanimal cells-have nucleus but lack CELL WALL VACUOLE CHLOROPLASTS -wide variety of shapesfungi tend to grow in long filaments called hyphaehave cell walls made of chitin rather than cellulosediffusion isthe movement of a substance from a region of high concentration to a region of lower concentration -gases and liquids diffuse the same way -diffusion happens much more quickly for GASESoxygen diffuses into cells where it is used forrespirationcarbon dioxide diffuses out of cells into the bloodstream and is thentaken to the lungs where it is exhaleddiffusion in liquids:if there are materials dissolved in a solution, those materials are called solutesif a solution has glucose dissolved in itwater is the solvent and glucose is the soluteselectively permeableallowing substances only of a certain size or charge to move easilytwo solutions have the same concentration of solutesisotonic (won't change)if one solution has more solutes (THUS a lower concentration of water)hypertonic if separated = net movement of water into hypertonic solutionif a solution has fewer solutes than another solutionhypotonic if separated = water will leave the hypotonic solution and move into the hypertonic solutionosmosisdiffusion of water across a selectively permeable membranewater will move into or out of cells depending on the concentration of water thatsurrounds the cellthe cytoplasm of a cell is mostlywaterif a cell is placed in fresh, pure water, the concentration of water inside the cell is less than outside andwater will diffuse into the cell via channels called aquaporins cell is hypertonic relative to fresh water water is hypotonic relative to the cellaquaporinsA transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membranehypotonicswell when placed in solutionhypertonicshrinks when placed in solutionsolutethe substance that is dissolvedsolventA liquid substance capable of dissolving other substancessolutionA homogeneous mixture of two or more substances solvent+soluteosmosis is biologically importantrequire no energy -move important materials into/out of cellcoccicluster of spherical shapesbaciliRod shaped bacteriaspirillispiral shaped bacteriacyanobacteriashape- filamentous no chloroplasts but chloroplasts seemed to evolve from cyanobacteriaplant cell chloroplastscarry out photosynthesis in thylakoid membranepassive transportRequires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient diffusion + facilitated diffusionactive transportEnergy-requiring process that moves material across a cell membrane against a concentration difference. use of ***ATPinside - outsidemembrane potentialmembrane potentialThe difference in electrical charge between the inside and outside of a cell, caused by a difference in the distribution of ions.Why diffusion is importantCO2 diffuses out of cells and into the bloodstream where it is then taken to the lungs, where it is exhaledmost chemical reactions in living organisms, including the process of digestion, requiresENZYMESmost enzymes are proteins and these are biological catalyststhey greatly increase the rate of a chemical reaction but are not themselves changed during the process Increase rate of chemical reaction Decrease energy needed (activation energy)enzymes speed up a wide variety of reactions, including hydrolysis, decomposition, and oxidationIncrease rate of chemical reaction Decrease energy needed (activation energy)the substrate of a reaction is the chemicalconstituents that are catalyzed by an enzyme will bind to a substrate to form an enzyme-substrate complex and in the reaction that followsthe substrate is changed to productsthe rate of reaction depends of a variety of factorsenzymes are especially important indigestionproteinsimportant as a STRUCTURAL element in bones, cartilage, hair, feathers, nails, and cell membranes. important as: enzymes, hormones, antibodies, and in oxygen to transport red blood cells -composed of polypeptide wrapped together in precise structurepepsinworks best at lower pHtrypsinsecrets by the pancreasany enzyme that digests proteins is aproteaseas proteins are digested, the polypeptide chains unravel and break up into small chains of amino acids calledpeptideslipids includefats and oils -used for energy storage and insulationlipids do not dissolve inwater but may dissolve in non polar compoundscarbohydratesinclude simple sugars such as glucose and sucrose and polysaccharides such as starch and cellulose. -important as structural compounds and a source of energy that can be used to make ATP. *cellulose*Digestion of Carbohydratesconverts polysaccharides and disaccharides into monosaccharides that can be absorbed into body cells -(begins in the mouth and is completed in the small intestine)-amylaseenzyme that breaks down starch produced in the mouth and in the small intestine where it clips polysaccharides into disaccharides and monosaccharidesrate of reactionmore substrate = faster reaction max rate reached when enzymes are saturated temperature higher temp= more energy more energy= more molecule movementIodineNormally yellow-brown Turns blue-black in presence of starchIn our osmosis experiment, the WATER moved across the membrane, not the solutesmost solutes are too big to move across a semi permeable membranecellular respirationC6H12O6 + O2 > CO2 + H2O + ATPdifference between respiration and fermentationrespiration generates more ATP -respiration uses Oxygenalcohol and lactic acid fermentationAlcohol Fermentation Produces: 2 ethanol 2 CO2 2 ATP Lactic Acid Fermentation Produces: 2 Lactic Acid 2 ATPyeastsimple, unicellular fungi Yeast works by creating enzymes that attack the complex sugars in flour and break them down into simple sugars. The sugar is then changed into alcohol and carbon dioxide.cellular respirationprocess that releases energy from food in the presence of oxygen -in eukaryotes occurs in the mitochondria where energy from food is converted into energy rich molecule, ATP. ATP is then used for many cellular processes, including active transport, molecule synthesis, muscle movement, any process requiring energy.organisms uses oxygen as the terminal electron acceptorAEROBIC respiration or another terminal electron acceptor (ABAerobic respiration) such as iron, mag, sulfate.aerobic respirationC6H12O6+O2>ATP+water+CO2photosynthesis converts light energy intochemical energy (which is stored in the bonds of sugar created)facultative anaerobesCan make enough ATP to survive using using fermentation or respiration.when oxygen is not availablethey use fermentation to produce a reduced amount of ATP C6H12O6>ATP+alcohol+CO2all organisms rely on this processphotosynthesisOrganisms that perform photosynthesis to obtain energy areautotrophs ("self-feeding")obtain energy from consuming other organisms (herbivores, carnivores, decomposers, etc.)HeterotrophsWhat is phtosynthesis?fixation of carbon 6H2O + 6CO2 + Sun Energy > C6H12O6 + 6O2cellular respirationThis is the main process of making ATP in plants and animals. Conversion of organic molecules into energy that can be used by cells C6H12O6 + 6O2 6H2O + 6CO2 + Energy (approximately 32-38 ATP)cellular respiration equationC6H12O6+6O2---> 6CO2+6H2O+ATPLight (light-dependent) reactionsgranaDark (light-independent) reactionsstromalight-dependent reactionsreactions of photosynthesis that use energy from light to produce ATP and NADPHLight Independent Reactions (Calvin Cycle)2nd stage of photosynthesis, occurs in stromaThe Light (dependent) Reaction (Photophosphorylation)Occurs in Grana on the thylakoid membrane Chlorophyll captures light energy Electron transport chains (cyclic and non-cyclic) Non cyclic: H2O is split and O2 is formed. Products are O2, ATP and NADPH Cyclic: produces ATPThe Light Independent (Dark) Reaction (the Calvin Cycle)This is the process of Carbon Fixation Occurs in the stroma The products of the Light reaction are used as energy to create organic molecules from CO2. 6 molecules of CO2 are used to create one molecule of Glucose through the Calvin cycle.Measuring LightHumans see wavelengths of 400 -700 nm. Measure light in foot candles (fc), which is equivalent to one lumen per square foot. Originally comes from the amount of light put out by one candle measured at one foot. Use 200.0 fc setting, if it gives you an error, move it up to 2000 fc. of photosynthesisis the means by which plants get and store energyin photosynthesis, plants and other protists "tie-up" solar energy (sunlight) by using it to make energy-rich simple sugars (including glucose.)a by-product of this reaction is the production of molecular oxygen (O2).general chemical reaction of photosynthesiswater+carbon dioxide+solar energy (sunlight)>>>>simple sugars+oxygenEquation for photosynthesis6CO2+6H2O+LIGHT>>>C6H12O6+6CO2process of making ATP is calledcellular respirationin respiration organic molecules react with oxygen indirectlyenzymes control the rate at which this reaction occurscarbs broken down=release of energy this energy released can be used to make ATPATP then can be used in cell to drive allenergy-requiring cellular processesrespirationoxygen is consumed (used up) and CO2 is producedequation for cellular respirationorganic molecules+oxygen>>>>water+carbon dioxide+released energyCalvin Cylcelight-independent reactions of photosynthesis in which energy from ATP and NADPH is used to build high-energy compounds such as sugar Calvin cycle IN THE FIXING OF CO2DNA is in the nucleus and is organized inchromosomes A chromosome is a molecule of DNA with proteins attached.DNA double helix is coiled onto proteins which in turn coil and form a chromatin fiber.DNA carries a code of lifeAlmost all metabolic processes that occur in a cell requires enzymes to proceed. DNA carries the code for these proteins. DNA is passed on from parents to children via gametes (in sexual reproduction).DNA-sugar phosphate backbone (deoxyribose) -nitrogenous bases -A>T -C>G complementary base pairing sequence of bases -5'>3' 5'= phosphate 3'= hydroxyl group BONDS= hydrogen and phosphodiesterDNA Profiling (aka DNA fingerprinting)Separate fragments according to size—gel electrophoresis DNA sample goes in well and electric current is applied DNA molecules are negatively charged, then go towards positive end (runs to red). Smaller DNA fragments move faster then bulky ones Use standard for size comparison longer bands = top shorter bands= bottomchromosomes become visiblewhen the cell is dividingDNA stretched out2 meters longchromosomes arelong sections of DNAportions of DNA are coding sections and are calledgeneshumans have 23 pairs of chromosomes46 chromosomes totalkarotypechromosomal composition of an individualDNA is read3'-5'DNA is made5' to 3'mRNA is formed5'-3'DNA SYNTHESIS5'-3'A-T2 hydrogen bondsC-G3 hydrogen bondschromosome 1largest chromosome 247 millionabout 6 billion base pairs in everycellribosehas one more oxygen atomhelicaseAn enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands. slices open hydrogen bonds between base pairstop strandleading strandbottom strandlagging strandleading strand= DNA polymerase just addsmatching base pairs all the way down the molecule primer- rna primase DNA polymeraselagging strandA discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.DNA ligaseA linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.PCR(polymerase chain reaction) multiple copies of a specific segment of DNA production of millions of copies of a particular stretch of DNA (only small amount of parent molecule available)restriction enzymesEnzyme that cuts DNA at a specific sequence of nucleotidesgel electrophoresisProcedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel separate by sizePCR primersShort DNA fragments that prepare DNA for a Polymerase Chain ReactionDNA fingerprintinganalysis of sections of DNA that have little or no known function, but vary widely from one individual to another, in order to identify individualsMitosispart of eukaryotic cell division during which the cell nucleus dividesprophaseChromosomes become visable, nuclear envelop dissolves, spindle forms chromatin condenses and becomes visible as chromosomesmetaphaseChromosomes line up in the middle of the cell align across the equatorial plateAnaphasePhase of mitosis in which the chromosomes separate and move to opposite ends of the cell paired chromosomes separate at the kinetochores and move to opposite polesTelophaseAfter the chromosome separates, the cell seals off, Final Phase of Mitosis. arrive at the opposite poles and new nuclear membranes formDNA amplificationCreation of many copies of a segment of DNA by the polymerase chain reactionHumans 46 chromosomes 23 pairs of homologous chromosomesN=number of chromosomes in gamete Diploid=cell with homologous chromosomes=2N Haploid=cell with only one chromosome from each homologous pair=NmRNARibonucleotide sequence Codons 3 adjacent bases=amino acid Polypeptide Chain of amino acidsrRNAtype of RNA that combines with proteins to form ribosomestRNAtransfer RNA; type of RNA that carries amino acids to the ribosometranscriptionthe process of the DNA serving as a template for mRNA starts when the enzyme RNA polymerase binds to the promoter, a specific site on the DNA. DNA unwinding. The enzyme then moves along the DNA in a 3'>5' direction- as it moves creating a complementary strand of mRNA.translationthe process of building the amino acid sequence based on the codons on the mRNA. mRNA read 5'>3'mitosisthe DNA in a cell replicates and the cell divides, resulting in two daughter cells that are identical to the original cell. # of chromosomes in daughter cell same as parent cellmeiosis# of chromosomes is reduced by half, allowing for important processes of reproduction gamete productionhaploidsex cells or gametes only have one copy of each chromosomediploid2 copies of every chromosome somatic cellsspermatogenesisprocess of forming spermoogenesisprocess of forming eggs or ovareduction divisionanother name for meiosis I, the division where homologous pairs separate.equational divisionAnother name for meiosis II because cells in meiosis II have the same number of chromosomes at the beginning and at the end of the process. PRODUCING 4 FROM 2dominantDescribes a trait that covers over, or dominates, another form of that trait.recessiveAn allele that is masked when a dominant allele is presentall nucleotide strands are built5'>3'fertilization occurs when gametesjoinwhat charge does DNA have?negativemeiosis1 diploid cell>4 haploid cells Preceded by S phase 2 stages Meiosis I Homologous chromosomes pair and separate Meiosis II Sister chromatids separate Used for sexual reproduction Genetically different gametes Crossing over & random assortmentTRANSCRIPTIONDNA=template Read 3'5' RNA polymerase Unwinds DNA+ synthesizes new RNA strand RNA bases Adenine, Uracil Cytosine, Guanine mRNA strand Made 5'3' Complementary to templateTRANSLATIONRibosome small and large subunit rRNA mRNA Read 5'>3' tRNAs Anticodon Amino acid attached='charged'Genotypes= 1:2:1 Phenotypes=3:1Heterozygote crossIncomplete dominanceHeterozygotes=intermediate phenotypeCodominanceHeterozygotes=both phenotypes expressed Human Blood Type (AB)Sex-linkedGene on X chromosome Males have phenotype more often than females Females have to be homozygous recessive to have phenotypegenotypeAn organism's genetic makeup, or allele combinations.PhenotypeAn organism's physical appearance, or visible traits.chi-sqaure testx^2=sigma E(O-E)^2/E Tests if observed data is different from expected values of a hypothesis H0 = There is no difference between the expected and observed values (ratio is 3:1) HA = There is a difference between the expected and observed values (ratio is not 3:1) O=observed E=expected Σ= summation symbol add the calculations for each phenotypeMendelian GeneticsComplete dominance R=dominant r=recessive Generations P (parental): RR X rr F1 (filial 1): offspring of P gen; Rr X Rr F2 (filial 2): offspring of F1 gen; Monohybrid cross (1 trait) Genotypes= 1:2:1 Phenotypes= 3:1Mendelian GeneticsComplete dominance R=dominant r=recessive Generations P (parental): RR X rr F1 (filial 1): offspring of P gen; Rr X Rr F2 (filial 2): offspring of F1 gen; Monohybrid cross (1 trait) Genotypes= 1:2:1 Phenotypes= 3:1 Dihybrid cross (2 traits) Genotypes= 1:2:2:1:4:1:2:2:1Hardy-Weinberg PrincipleUnderstanding how allele frequencies change in a population States that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. Used as a null model