BIOL 1201 Exam 1 Study Guide Origins of Life A few centuries ago peoples thought new things appeared all the time spontaneous generation Spontaneous Generation was refuted in the mid 1800s by Louis Pasteur o Hypothesis spontaneous generation of life exists o Boiled broth in a flask to kill preexisting microorganisms as broth cools condensed water collects sealing the mouth off of the flask life was not created if neck is later broken off outside air can carry microorganisms into broth life is now created o Null hypothesis experiment essentially destroyed spontaneous generation theory Conditions of Early Earth s Atmosphere o CO2 CH4 NH3 H2 N2 HCl H2S H2O similar to Jupiter today o No free oxygen O2 or O3 all of todays oxygen was created through photosynthesis o Possible energies to catalyze chemical reactions Frequent storms with lots of lightening Frequent volcanic eruptions Frequent meteor impacts UV light from sun no ozone layer lots of energy to make break chemical bonds Earth Before Life Arose hypothesis o Earth is about 4 6 billion years old Radiometric dating of moon rocks meteorites because they were essentially formed at the same time o Life arose about 3 8 billion years ago Chemical traces in rocks say 3 8 billion years ago but it took a while for these traces to build up Some scientist think we started having life as soon as water formed on the planet Fossil bacteria in rocks 3 5 billion years ago date rock around fossil No spontaneous generation now but it must have happened then How to Assemble a Living Thing organic through metabolism o Accumulation of organic molecules eating some can turn inorganic compounds into Miller Urey Experiment 1950s chemical evolution Purified water boiled in a flask water goes up as water vapor to a flask with sparks simulating lightening storms adding gasses of primeval atmosphere water cools returns to original flask After a few days water turned brownish tested it no new life but some nucleotides basic amino acids were formed Failed but organic molecules appear after only a few days relevant o Catalyze reactions being alive having cells require reactions to be sped up enzymes mostly proteins o Reproduce from stored genetic information all living things today use DNA aka genomic material to store genetic info Central Dogma of Biology DNA RNA Protein Needs proteins to synthesize more DNA Simplest explanation likely RNA was the first substance to store genetic material catalyze reactions example viruses Ribozymes RNA enzymes RNA molecule that can catalyze reactions especially those involved in synthesis processing of RNA itself RNA that acts like enzymes Conclusion Earliest cells used RNA to store info ribozymes to catalyze reactions o Separate the living thing from the outside environment have an inside outside with something separating the two membrane most likely common to all protocells Microspheres as Proto cells just add fat protein to water then shake Just the right mixture of organic materials including RNA bonded together in just the right way to form the first living cells on the planet o Water Elements Energy Prebiotic Soup amino acids nucleotides lipids sugars Microsphere like proto cells surrounding more complex organic molecules like RNA carbohydrates proteins lipids First Prokaryotes All living things came from this first prokaryote have resemblances to all living things All parts of your body use the same DNA polymer of nucleotides but only activate certain parts of it to perform different tasks DNA Molecule of Heredity DNA is a polymer of nucleotides Structure o DNA double helix or dsDNA double stranded DNA Watson Crick discovered structure of DNA DNA is double helix of two nucleotide strands Complementary base pairs hold the two DNA strands together run in opposite directions Left goes P S right goes S P top bottom Maurice Wilkins Rosalind Franklin knew that DNA formed a helix by the patterns seen in x ray diffraction o Nucleotide 3 parts 4 nucleotides for DNA All have Pentose sugar sugar with 5 carbons labeled 1 2 3 4 5 Phosphate group off 5 be able to recognize they are nucleotides by these things Variable Component 1 of 4 Nitrogenous Bases Adenine A Thymine T Cytosine C Guanine G o Nucleotide Strand Sugar Phosphate backbone bases Phosphate end 5 to sugar end 3 Complimentary strand strand that binds to it goes in the opposite direction antiparallel base pairs to the first strand Chargaff s Rule A T C G A T 2 hydrogen bonds C G 3 hydrogen bonds o Can break apart from dsDNA to single strand by outing in water increase temperature Importance of DNA Eukaryotic Cell Cycle o DNA is where genes are found o Genes encode the information required to make proteins Genes are like a dimmer switch to the extent of how activated they are o Order of nucleotides in a DNA molecule can encode a large amount of information o Like a computer with 1 0 ATCG program is in every gene can code for particular protein o DNA 10 molecules long has 410 different possible combinations o DNA chromosomes genes cells o G1 growth takes place along with diffraction o S synthesis of DNA chromosomes are duplicated o G2 cell growth o Mitosis cell division o One cell forms two cells when replicating it divides 23 pairs of chromosomes so it can split them equally between the two daughter cells during mitosis o Cancers happen where replication happens most often when mistakes are made in replicating cells or when the cells constantly replicate without informing the cell that the new cell needs information tumor DNA Replication o Part S of interphase o Begins occurs ends o Semiconservative Replication Model Called this because half is conserved used to make the other side Chromosome one DNA double helix duplicated chromosome sister chromatins old new Replication bubble forms in center ish of the chromosome with replication forks at both ends move in opposite directions Separation of parental DNA helix Enzyme used to catalyze the separation of DNA separated DNA denatured DNA Producing two template strands to synthesize a new strand Incorporation of complimentary nucleotides Add the correct base to the exposed nucleotide Another enzyme recognizes the single strand of DNA grabs the corresponding base pair in solution in your cells from foods needed to make a new dsDNA of nucleotides o 1 out of 100 000 bases makes a mistake causing a DNA instability bubble at that spot in the helix fixed by DNA repair enzymes if not a mutation is caused can be carried on to future
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