How life Began Hypotheses vs theory observations the n hypotheses then you test it to support or not support it Scientific method The simplest explanation is the most likely one Multiply theories on how life begin Earth formed over 4 6 billion years ago Life began 4 billion years ago Theory of spontaneous generation life Disproven theory Life begins out of nothing One day there was nothing Then life began out of nowhere Still happened to this day 1609 a monk would observe leafs falling into water Assume turn into fish Maggots out of meat Guy who invented pasteurizing of milk Louis Pastur did an experiment to see if this was true Closed off a nutriment rich broth boiled it closed it off allowing the pressure to sustain No observable growth for weeks His hypotheses Does spontaneous generation of life occur Null hypotheses BUT 4 billion years ago this had to happen Atmosphere of earth at the beginning of earth We look at other planets and moons in our galaxy to get an idea of what it was like Looking at redox oxidation reaction in earliest earth rocks it looks like their was very little of any oxygen O2 and O3 ozone No breathable oxygen 20 oxygen in atmosphere today comparison All produced during photosynthesis Energy system in the form of volcanos Lots of lightening UV from sun no ozone CO2 CH4 NH3 H2 N2 HCl H2S H2O similar to Jupiter We get the info of the earth being 4 6 billion years old from samples of the moon and meteorites Some scientist think life began on earth as soon as we had water Chemical evolution Competing hypotheses life came from another planet Asteroid came to earth with bacteria Miller and Urey Urey noble prize winner Miller grad student Did can experiment to try and spontaneously create life with the same conditions early earth would have had Did not create life But did start to get the building blocks of life Attempted experiment in 1950 s How to assemble a living thing list The only place where life has been known to exist for sure is on earth 1 Need an accumulation of living compounds Organic compounds 4 billion years ago those compounds would of come from the earths atmosphere 2 Something that will speed up chemical reactions Enzymes Which are most of the time are proteins Essential Dogma of Biology applies to 3 as well All living things with some exceptions use DNA to make RNA and then use that RNA in some form to make protein Which came first DNA or protein Turns out RNA more than likely came first First organic material to store material and first to catalysts organic reactions Ribozymes RNA molecules that catalyst actions especially those involved in synthesis and processing of RNA itself 3 Store genetic info DNA Prokaryotes are without a nucleus but still have DNA 4 Have something that separates the inside from the outside membrane You cant be smaller than a cell and still be considered a living thing Microspheres hydrophobic on the inside Outside hydrophilic In protocells Surround more complex organic molecules like RNA Made of Phosphate Group off of 5 prime carbon a pentose sugar Deoxyribose 5 carbons 1 5 prime nitrogenous base 4 types DNA is a good example of a polymer If we have one it s a monomer Two dinomer Three tri Etc a lot of them then polymer DNA is a polymer of nucleotides DNA The four nucleotides of DNA Thymine Cytosine Adenine Guanine When DNA is replicated mistakes always happen We still don t know what 40 of the human genome is used for Anti parallel double stranded helix Watson and Crick is credited for the shape of DNA Backbone on DNA runs phosphate to sugar 5 prime to the 3 prime Hydrogen bond 2 between A T Weak electrostatic bond Meaning its not sharing electrons Opposite bonds attract 3 in G C The double strand has to be unwound to be read Can be used as a template to make more DNA or to make RNA Chargaff s Rule A T C T Polymerase chain reaction PCR How to break DNA bonds Freezing them stops the molecules from vibrating Increase of temp vibrate more Can be so great it breaks them apart This is how they become single stranded How many different combinations can we get with the 4 nucleotides in the span of 10 4 10 1 048 576 Chromosomes consist of genes Genes of nucleotides Cell Cycle Starts with one cell Ends with two cells When replicating it divides 23 pairs of chromosomes so it can split those equally between the two daughter cells during mitosis Syntheses of DNA chromosomes are duplicated G1 growth takes place along with diffraction G2 cell growth Mitosis cell division Cancer is most common in where replication happens most often EX colon cancer Denaturing double strand to single Also called unzipping In a living organism we do this by speeding up that chemical reaction with enzymes In this case a protein DNA repair enzymes recognize when there is a bubble in the DNA that has formed due to the wrong nucleotide being brought in The problem is all they see is there is a mismatch Correct one of the two strands If they correct the proper strand the mutation disappears If not then the mutation stays and persist into the next generation of cells Happens about one every 100000 bases Get nucleiotide in food Semi conservative replication model called that cause half is conserved and used to make the other side Sister chromatids half old half new Unzippig begins at the center of the chromosome forming something that looks like a bubble On the edges called a fork Enzyme that unwinds the DNA is called helicase Enzyme that copies it is called DNA polymerase gets continuously copied P to S The other does it segmented Waiting for the polymerase to unzip DNA ligase glues together the sugar phosphate backbone for the segmented on The type of bond is phosphodiester Majority of the outside of the cell is water Cytoplasm When we say DNA is turned on it is read into RNA Maurice Wilkins Rosalind Franklin knew that DNA formed a helix by the patterns seen in X ray diffraction Pauling noble prize winner for the structure of DNA Gene related How are genes and proteins related 1 gene RNA protein 2 gene segment of DNA located at a particular place locus on a chromosome 3 DNA codes for specific animo acids sequence in a protein or for the RNA that helps make proteins DNA v RNA DNA deoxyribose sugar blueprint a t g c double stranded RNA single stranded ribose sugar a u uracil g c function based on type messenger RNA transfer RNA ribosomal RNA structural difference ribose has a hydroxide and deoxyribose has a hydrogen on the 2 prime 3 sequences of
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