AP Biology Unit 6 Study Guide

-effect of solute concentration -Solute potential (Ψs) = −iCRT -i = number of particles the molecule will make in water -C = Molar concentration -R = Pressure constant = 0.0831 liter bar/mole K -T = Temperature in degrees Kelvin = 273 + °C -pure water at atmospheric pressure has a solute potential of zero -as solute is added, the value for solute potential becomes more negative and causes water potential to decrease and water will tend to move into the solution

-handle volumes from 2-20 µL -reading the pipette: Top=Tens, Middle=Ones, Bottom=Tenths

-used for volumes of 20-200 µL -reading the pipette: Top=Hundreds, Middle=Tens, Bottom=Ones

-used for volumes of 200-1000 µL -reading the pipette: convert µL to mL, Top=Ones, Middle=Tenths, Bottom=Hundredths

-micropipettes work on the principle of air pressure -each pipette has a specific range in which it works accurately -NEVER set a pipette outside of its range as this can damage the calibration mechanism -you MUST USE A TIP when drawing in liquid or you will ruin the air pressure mechanism on these very expensive tools -use a fresh, sterile tip for each sample so that the least amount of contamination happens for each experiment -there are two stopping points when depressing the control button. -the first \"stop\" is the calibration point and lets you draw in the proper volume -push all the way down on the control button to find the second \"stop,\" which is used to expel a sample -centrifuges spin samples at high speed and are used to: mix different components of a sample and separate different components of a sample by density -centrifuges consist of a canister with a lid, which contains a rotor -test tubes containing samples are placed in the rotor -the samples within the rotor must be properly balanced, or the forces created by the centrifuge's high speed can damage the instrument -to balance a rotor, samples of equal weight must be placed opposite one another

-Polymerase chain reaction (PCR) is a quick and selective technique that amplifies any specific target segment within one or many DNA molecules -it is effective when the source of DNA is scanty or impure -Process Steps: 1. Denaturation: heat briefly to separate DNA strands 2. Annealing: cool to allow primers to form hydrogen bonds 3. Extension: DNA polymerase adds nucleotides -process occurs in 3 cycles, where cycle 1 yields 2 molecules, cycle 2 yields 4 molecules, and cycle 3 yields 8 molecules -at the end of the process 2 molecules match the target sequence

-DNA template: DNA you want to amplify from -Primers: bind to DNA and replication begins at these primed regions. Two primers are created specifically for the area of interest because they are both complementary to the nucleotide sequences at the beginning and the end of the section of DNA we want to amplify -Buffer: provides proper environment for polymerase to function -Deoxynucleotide-triphosphates (dNTPs): mixture of dATP, dGTP, dTTP, dCTP (building blocks of DNA) -Mg: cofactor for Taq and changes salt conditions for reaction -Taq Polymerase: adds base pairs

-electrophoresis is used for separating nucleic acids or proteins that differ in size, electrical charge, or other physical properties -Process Steps: 1. Each sample, a mixture of DNA molecules, is placed in a separate well near one end of a thin slab of gel. The gel is set into a small plastic support and immersed in an aqueous solution in a tray with electrodes at each end 2. When the current is turned on, the negatively charged DNA molecules move toward the positive electrode, with shorter molecules moving faster than longer ones

-Gel -Buffer: provides ions to carry a current and for pH balance -Ethidium Bromide: stains the DNA to make it visible to UV light -UV Light Source: needed to see the DNA -DNA Ladder: standard ladder with known fragment lengths that can be used to convert distance on the gel to the actual distance -Loading Buffer: made with glycerol to weigh down the DNA and dye to track progress of DNA

-compare DNA samples to the standard \"Reference\" sample 1. The \"standard\" contains DNA fragments of known length (100 bp, 200, 300, ...., 1000, 1200, 1517) 2. The distance a fragment travels is inversely proportional to the log of the number of base pairs in the sample

1. Using a ruler, measure the migration distance of each band for all samples. Measure the distance in millimeters from the bottom of the loading well to each center of each DNA band and record your numbers in an organized table. 2. To make an accurate estimate of the fragment sizes for either the crime scene or the suspects, a standard curve (also called reference curve) is created using the distance (x-axis) and fragment size (y-axis) data from whatever is used as your reference marker (where segments DNA migrates to known distances). Using and semi-log graph paper, plot distance versus size for each band. On the graph, draw a line/curve joining the points. Extend the line/curve all the way to the right hand edge of the graph. 3. To estimate the size of an unknown crime scene or suspect fragment find the distance (on the x axis) that fragment traveled on your gel. Locate that distance on the x-axis of your standard graph. From that position on the x-axis, read up to the standard line, and then follow the graph line to over to the y-axis. Where the graph line meets the y-axis is the approximate size of your unknown DNA fragment.

-micropipettes inaccurately measured the materials -current did not work

the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings

-Plasmids: circular pieces of DNA that are found outside of the main bacterial chromosome and carry their own genes to bring foreign genes into a bacterial cell. They will help us introduce foreign DNA into the E. coli bacteria -Competent Cells: cells that have cell walls that allow DNA to pass through easily. In this lab, the E. coli bacteria must be competent to allow the taking in of the foreign DNA -Sterile Lab Techniques: include avoiding contact with contaminated surfaces by not directly touching the tips of the tools, not placing the tools onto contaminated surfaces, and not touching the agar gel. This is important for this lab because outside bacteria should not be introduced into the experiment

-if AMP is not fresh, it will not work well. -heat shock must be at 42 ℃; if higher, will kill bacteria; if lower, efficiency will be lower -extra hot spreading rod will kill bacteria on plate -if cells do not shake at 37 ℃ for 30 minutes, efficiency will go down; if cells do not shake at all, no bacteria will be transformed -if the incubator is lower than 37 ℃, the efficiency will go down; if the incubator is higher than 37 ℃, the bacteria might die -if cells are not competent, they will not accept the plasmid -there is a maximum amount of plasmid that can be used; if too much plasmid is used, efficiency will decrease. This is because the extra plasmid may try to enter bacteria already transformed and thus it won't increase the efficiency; if not enough plasmid is used, efficiency will decrease

-Agar+Ampicillin+Plasmid=colonies -Agar+Ampicillin-Plasmid=no growth -Agar+Plasmid=lawn -Agar-Plasmid=lawn

-A technology that includes the process of manipulating or altering the genetic material of a cell resulting in desirable functions or outcomes that would not occur naturally -Ex: cloning to create embryonic stem cells; done by inserting the nucleus of another organism into the egg cell then simulating the egg to divide many times to form a blastocyst with many possibilities for differentiation; pros: helpful for repair and curing genetic diseases; cons: oftentimes, a body will react negatively to the invasion of strange cells -Ex: resilient corals are genetically altered to be resistant to threats posed by environmental changes and overfishing; done by splicing the most beneficial coral genes into specimens of all coral species; pros: allow reefs to be resistant harm from environmental change; cons: could outcompete existing species, therefore all coral species would have to be genetically modified to maintain balance of species in the ecosystem