BSC2011 Unit 1 Notes Slide set 1 I Scientific Inquiry A The scientific process and falsifiability The scientific process the investigation of rational concepts that can be evaluated by observation and experimentation i e science is not relevant to ALL issues Inductive Reasoning generalize from a large body of consistent observations Deductive Reasoning hypothesis driven science Steps of scientific process 1 Observe something qualitative or quantitative 2 Ask a question 3 Formulate a hypothesis tentative explanation of observations 4 Make a prediction 5 Experiment test performed to test validity 6 Revise hypothesis if hypothesis is incorrect OAHPER Old Abraham Has Physical Education Rarely Hypothesis a proposed explanation for an observed phenomenon that leads to a certain prediction Tentative explanation of observations Null Hypothesis a statement that negates a hypothesis this is what you want to test to try and disprove A scientist proposes a hypothesis and then evaluates its prediction by experimentation or further observation that tries to disprove the null hypothesis Statistical analysis of the results shows that the null hypothesis is true less than 5 of the time then we say that the results of the study are statistically significant and we reject the null hypothesis because the probability of the null hypothesis is 05 Science requires that a hypothesis be testable and falsifiable and that observations be repeatable Example Observe a non working flashlight then ask why doesn t it work you come up with a hypothesis that you either need to change the batteries or change the light bulb The null hypotheses are that the batteries have no effect or that the bulb has no effect After the test is done do the results falsify reject the null hypothesis Theory a hypothesis or set of hypotheses that is consistent with virtually all of the available evidence also called the law of nature Falsifiability there must be some experiment or possible discovery that could potentially prove the hypothesis theory untrue B We ignore science at our own peril junk science pseudoscience Junk Science the selective enlistment of science to serve a political and or economic agenda Pseudoscience indifferent to criteria of valid evidence It does not emphasize meaningful controlled repeatable scientific experiments It relies on unverifiable eyewitness testimony stories and tall tales hearsay rumor and dubious anecdotes It resorts to magical thinking and unexplainable influences and connections between things Examples include geocentrism astrology phrenology graphology and pyramidology II Review A Central Dogma flow of genetic information is basic to all living things Three entities three processes DNA RNA Protein Replication Transcription Translation Replication DNA is copied into DNA Transcription DNA is transcribed into mRNA Translation mRNA codons are translated into a protein Gene Expression includes transcription and translation Translation process by which transcribed mRNA in the nucleus is decoded into a specific protein at a ribosome in the cytoplasm a mRNA codon corresponds to a specific amino acid in a protein Genetic Code a codon triplet of 3 mRNA bases codes for 1 amino acid The code is redundant multiple codons may code for the same amino acid due to the 3rd base wobble The code is virtually universal indicative of an ancient origin of the common ancestor of modern life forms The genetic code is essentially the same for all organisms therefore a gene from an organism can theoretically be expressed by any other organism B Proteins 1 The majority of an organism s genes code for proteins 2 Tens of thousands of different proteins in a human 50 b Types and Functions enzymes catalyze reactions e g DNA polymerase structural support e g keratin collagen transport other molecules e g hemoglobin hormones coordinate cell or organ activities e g insulin receptors respond to and bind to chemical stimuli e g olfactory receptors G proteins defense e g antibodies contractile motor proteins e g actin myosin storage of amino acid reserves e g ovalbumin The genes expressed and proteins made in a muscle cell will largely differ from the genes expressed and proteins made in a brain cell A particular cell must regulate which genes get expresses and when C Mutation a change in the genetic material of DNA of a cell Can be large scale sections of chromosomes get rearranged Can be small scale as in a point mutation a change in just one nucleotide in a gene A mutation may or may not alter a codon and the amino acid for which it codes Examples nucleotide substitutions nucleotide insertions or deletions Nucleotide nt substitution may or may not change the amino acid that was originally coded may or may not result in a functional protein Silent mutation If you get no amino acid change because the genetic code has some redundancy due to the 3rd base wobble Missense mutation amino acid changes Nucleotide indel causes a frame shift mutation by altering the codon reading frame Nonsense mutation an early or no stop signal and no protein Mutational change in even one protein can have a huge ripple effect among many protein protein interactions III The generic Basis of Development Proper embryonic development requires that the correct genes be expressed at the correct time and in the correct location A Molecular processes guiding development For a single fertilized egg cell ZYGOTE to develop into a multicellular embryo and later an adult it requires 1 Cell signaling Cells use signaling mechanisms in order to 2 Gene regulation 3 Stages of Cell Signaling a regulate cell activities turn a gene off on change cell shape cell division and death b communicate with other cells neurotransmitters secreted into synapses hormones secreted into the circulatory system to target specific cells tissues and organs when to produce and release digestive enzymes when to stop eating 1 Reception a signal molecule is received by a receptor molecule on the cell membrane or inside the cell 2 Transduction a stepwise series of chemical reactions initiated by an activated receptor molecule to bring about a specific cellular response 3 Response the end result of a specific signaling pathway Gene regulation the control of gene expression i e regulating transcription and translation Some genes have constitutive expression i e always on while other genes have facultative expressions they are expressed on or repressed off as needed Genes must be regulated in
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