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Study Guide for Exam 2

by: Monica Weisenbach

Study Guide for Exam 2 BIO110

Marketplace > University of Massachusetts > Biology > BIO110 > Study Guide for Exam 2
Monica Weisenbach
GPA 3.819
Introductory Biology for Science Majors
Christiane Healey

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About this Document

This is a study guide from the second part of the course. It covers everything from the lectures since the last exam, and a little from the discussions. Good luck!
Introductory Biology for Science Majors
Christiane Healey
Study Guide
UMass, Umass Amherst, Biology, 110, Healey
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This 8 page Study Guide was uploaded by Monica Weisenbach on Saturday March 28, 2015. The Study Guide belongs to BIO110 at University of Massachusetts taught by Christiane Healey in Spring2015. Since its upload, it has received 170 views. For similar materials see Introductory Biology for Science Majors in Biology at University of Massachusetts.


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Date Created: 03/28/15
Study Guide for Exam 2 DNA Forensics DNA can be used to place people onat crime scenes DNA evidence is not conclusive on its own it must be combined with other evidence Karyotype a layout of the chromosomes m versionsvariants of the genes your genotype Homozygous two of the same variants AA or aa Heterozygous two different variants Aa Some traits are dominant need only one variant to be expressed while others are recessive need two of the same variant to be expressed Codependent traits alleles aren t always as neat as dominantrecessive think sicklecell anemia where AA is 100 sicklecell aa is 100 normal while Aa is 50 of both 1M AA AA Gel Electrophoresis a way to get the portrait of a DNA evidence DNA is negativelycharged and it is pulled through the gel by a positive charge at one end separating into size number of base pairs Shorter DNA strands have a higher proportional negative charge so go further bel DNA f quot hue z 00quotquot o 0W Recombinant DNA Restriction enzymes are enzymes that snip DNA at certain sequences They can be used to cut out genes of interest Restriction enzymes create a sticky end or overhang S c 39AAT39rcT l 3 CTTAA C9 5 I 539 6 AATTC 3 3 CTTAAW waxamount DNA snipped by the same restriction enzyme can be matched up DNA ligase can be used to stitch the pieces together even if the pieces are from different organisms An example of this is how the insulin gene can be inserted into bacteria plasmids which then produce insulin Epigenetics Epigenome the record of the chemical modifications to DNA and it s expression potential Epigenetics the study of the transcriptional potentialgene expression of the genome rather than alterations of the gene itself Epigenetics is what tells cells which all have the same DNA what to express and what type of cell to turn into Epigenetic Modifications chemical groups attached to patches of DNA that change its expression Gene Therapy Gene Therapy the procedure of introducing a functional gene into someone who carries a faulty version Viruses are used to get the gene into the correct cells Viruses are useful for this because viruses have to hijack a cell to do anything Viruses are also very specific on which cells they infect so the genes can be put into the targeted area What happens typically is that 1 An RNA version of a normal human virus is inserted into a harmless RNA virus 2 The targeted cells are removed and are injected with the virus so the viral DNA can get to the cells chromosomes 3 The engineered cells are injected back into the person Less typically the modified virus can just be injected into the person although this is less precise and more likely to go awry Dangers of gene therapy If the virus inserts in the wrong spot protein synthesis could be messed up Cancer risk could be heightened down the road Jesse Gelsinger died in a human trial for gene therapy in 1999 because of a reaction to the vector virus which prompted the slowdown of trials Stem Cells Stem cells unique cells that can selfrenew for an organism s life that are capable of reproducing without changing developmental potential What do stem cells do They are unspecialized capable of becoming any cell Development growing organs the body Tissue homeostasis replacing cells in the body as they die Tissue repair after injury There are 3 types of stem cell cell reproduction Symmetric Asymmetric Selfrenewal Selfrenewal O C O f C bllr cc Symmetric g Differentiation ccii Why do stem cells reproduce less often It s because reproducing less lessens the chance of copying errors Their differentiated daughter cells reproduce to create more and more cells of that type There are 3 levels of stem cell ability Totipotent capable of becoming any cell in the body and supporting tissues Pluripotent capable of becoming any cell in the body Multipotent capable of becoming any cell of a certain tissueorgan very limited potentiality Types of stem cells Embryonic Stem Cells ESCs pluripotent extracted during the first week from discarded IVF embryos Adult Stem Cells multipotent are found rarely in areas of the body Induced Pluripotent Stem Cells iPSCs differentiated cells turned back into stem cells with methods that trigger the pathwayscell types to revert the cell back to its early stages A Japanese team was the first to narrow down which triggers were the important ones working on mouse cells ESCs are still the gold standard because iPSCs are not completely reprogrammed There are subtle yet important differences between ESCs and iPSCs Knowing exactly what the cell will do is very important because an iPSC reverting back to a skin cell in the brain would be very bad Teratomas are very weird tumors made of different types of tissue it s a possible outcome of injecting ESCsiPSCs into a person or other abnormal stem cell behavior during the early stages of life Evolution Evolution is a scientific theory explaining how present organisms changed over the years and why the changes happened also the change in relative frequency of alleles in a population Darwin s finches The finches had diversified into types of finches with different sized beaks These beaks were adept at eating different types of seeds One time there was a drought and famine which eliminated the seeds that the thinbeaked finches ate The next year the average beak size of the adult birds and chicks was higher than in the years before the famine Evolution in action All organisms are descended from a common ancestor and have changed through natural selection principally with some other selections in plays as well Individuals develop but do not evolve only populations evolve What are the mechanisms of evolutionary change Mufations highly significant for an individual less so for a population Mutations are too infrequent to spread easily and unlikely to change one allele into another Genetic Flow the movement of individuals between populations adding or subtracting alleles from the population Most populations are not completely separated allowing for immigration and emigration Genetic Drift random chance causing a shift in the frequency of alleles Natural Selection environmental pressure favoring one allele over another Environmental pressures include temperature predators food supply shelter rainfall or mates sexual selection Fitness lifetime reproductive success The more an organism procreates the more its genes will be passed on Beneficial alleles are passed on by improved aness Adaptation a trait that enhances an organisms ability to survive versus those that don t have those traits There must be phenotypic variation but the trait must be heritable It is possible in a way to have natural selection without evolution Whether or not a type of water bug has spines depends on the predators in the area The spines are not heritable but a population may end up 100 spined due to predation Genetic Bottleneck Genetic bottlenecks occur when something happens and many individuals of a population are wiped out This removes many alleles and a lot of the variation from the population This harms the population as more genetic variation leads to more ability to adapt to changing environmental conditions Speciation Speciation the splitting of a species into two daughter species This occurs when gene flow is interrupted for long enough for the two populations organisms to evolve enough to be incompatible Species the definition depends Biological species concept two organisms populations that cannot interbreed Morphological species concept differentiating species based on skeletal differences in use for organisms like dinosaurs Phylogenetic species concept using genetic evidence to create evolutionary relation charts between organismspopulations The boundary between closelyrelated species is not always very clear Subspecies different populations that can likely interbreed but are geographically distinctdistant also used when biologists don t have enough knowledge to say two organisms are different species Hybrids some different species interbreed very rarely but not enough to be considered the same species Fling species a series in which connected populations can interbreed with the ones nearest to them but populations on either end of the ring cannot interbreed Allopatric Speciation geographic features like mountains or the Grand Canyon can separate populations for enough time to create two species Allopatric living in different geographic areas Sympatric living in the same geographic area Examples of Speciation Horses and donkeys are separate species despite the presence of mules because mules are sterile Grizzly bears and polar bears are considered separate species because of geographic habits and barriers although they are capable of interbreeding The two species were once separated by the last ice age but their habitat ranges may be starting to overlap again Dogs are breeds of the same species Even with physical size differences preventing copulation the two breeds can likely be interbred Miscellaneous The Supreme Court allowed the patenting of GMOs and artificial sequences The BRCA gene was once patented but has not held up Functioning labgrown kidneys have been transplanted into rats Organs can be stripped of everything but the connective tissue and seeded with new cells It s in the early stages but it could greatly reduce the waittime for donor organs Lactose Tolerance Approximately 23 of the world can t digest lactose after early childhood There are a few different variations in the area of the genome that controls the expression of the gene that produces lactase that lead to being able to digest lactose later on in life These variations popped up in regions that depended on cows Reasons include milk being cleaner than the water milk being a nutritious food in a famine those who couldn t digest it would be weakened or killed


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