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Biology 1500 Test 1 Notes

by: Kaitlynn Notetaker

Biology 1500 Test 1 Notes BIO_SC 1010 - 02

Kaitlynn Notetaker
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Krebs Cycle, Glycolysis, Periods of Life on Earth, Eukaryotes, Prokaryotes, Mitosis, Meiosis
General Principles and Concepts of Biology
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This 8 page Class Notes was uploaded by Kaitlynn Notetaker on Wednesday September 21, 2016. The Class Notes belongs to BIO_SC 1010 - 02 at University of Missouri - Columbia taught by Staff in Fall 2016. Since its upload, it has received 5 views. For similar materials see General Principles and Concepts of Biology in Biology at University of Missouri - Columbia.

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Date Created: 09/21/16
The Origin of Life • How old is the universe? ◦ 13.7 billion years old • How old is Earth? ◦ 4.6 billion years old • Hadean Period - 4.6 to 3.8 billion years ago; period before life existed ◦ Zerchean crystal inAustralian oldest rock on Earth ◦ Oldest rocks are moon rocks ◦ asteroids and geologic subduction destroyed ancient crust and almost no rocks survive from that time • What was the first kind of life we know about? ◦ Bacteria • How long has life existed on Earth? ◦ 3-4 billion years • Life (prokaryotes) 1st appeared ~3.8 billion years ago ◦ Archean Period - 3.8 to 2.5 billion years ago; only prokaryotes existed. Just water on earth, some volcanic activity. ‣ No Large continents formed until lateArchean ‣ Sun was 1/3 dimmer; days were 15 hours long because sun was 1/3 dimmer • Proterozoic Period- 2.5 billion to 540 million years ago ◦ Period before abundant, complex life ◦ O2 increased in oceans and atmosphere ◦ a # of IceAges occurred • Sometime between 1.8 and 2.8 billion years ago new type of cell with nucleus appeared=eukaryotes ◦ Don't fossilize well ◦ oldest fossils of multicellular are 1.2 billion year old algae • Phanerozoic Period - 540 million years ago to present ◦ period of abundant animal life; still in this one • "I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended to forgo its use." Galileo Galilei Early Earth • When life 1st evolved, atmosphere believed to contain N2, CO2, methane (CH4), ammonia (NH3) but no O2 ◦ This made it a reducing atmosphere which favored formation of organic molecules (compounds with C-C and C-H bonds) ◦ Lots of heat, lightning, and radiation provided the energy ◦ But no O2 meant no ozone layer and hi UV from sun would break down organics as soon as they formed ◦ Growing evidence that life may have begun at deep sea vents ‣ Must have broken down high energy molecules for energy ‣ Right reactants and conditions exist there ‣ Chemoautotrophic prokaryotes live around deep sea vents • 1st evidence for life is fossil carbon grains in 3.8 byo rocks that have 12C to 13C ratio found only in living organisms or their remnants ◦ Anything that takes carbon dioxide they have 12C • There are 3.5 byo fossil stromatolites ◦ 1.5 bill year old fossils in the Ozarks ◦ formed only by colonies of cyanobacteria found inAustralia and Bahamas • All life requires energy, C, and H sources ◦ photosynthetic or chemoautotrophic prokaryotes can make own organic mols ◦ others have to use existing organic mols • Some of the 1st photosynthetic bacts ( >3.5 bya) had a photosystem that split H2S to get Hs ◦ released S2 as a waste product ◦ Ph1 evolved ~3.5 by a from #4 above; is most efficient NRG collecting process known (~100%) • Ph 1= Photosytem 1 • NRG= energy ◦ couldn't be in top water column b/c of high UV light so they were low in the water column • PH II evolved from Ph 1 ~3.2 by a in cyanobacts ◦ it was able to split H2O to get Hs and produced O2 as a waste product • Methanogens are chemoautotrophs that collect H2 and CO2 for use in their metabolism and glue off CH4 ◦ exist in sewage, garbage dumps, and cow's rumen • One of the missions of the rover Curiosity is to examine Mars. How does it do this? ◦ Tunable Laser Spectrometer performs precision measurements of oxygen and carbon isotope ratios in CO2 and methane to distinguish b/w their geochemical and biological origin • Appearance ofAerobic Life • From ~3.2 by a when PH II evolved until ~2.5 bya, O2 it produced was used up in oxidizing organic waste in the ocean ◦ ~2.5 by a free O2 began to accumulate 1st in oceans then in atmosphere • Dated sediments show ocean was rich in dissolved Fe2+ (ferrous) more than 2.5 bill yrs ago ◦ ~2.5 bill yrs ago O2 liberated by Ph II began to oxidize Fe2+ to Fe3+ (ferric) which is insoluble in H20 and forms Fe2O3 (rust). Proof that there was O2. ◦ Over time oceans, then atmosphere became enriched with free O2 • Prokaryotes • Two types of prokaryotes evolved: Bacteria andArchaea ◦ form 2 of the 3 domains of life Archaea Eukarya ◦ 3rd is Eurkarya Bacteria Genes LUCCA • Bacts split from last common ancestor of all life about 3.5 bya ◦ Arch and Euks split 1.8-2.8 bya ‣ Many believe thatArchs are more closely related to Euks than to bacts • One problem in establishing relationship is horizontal gene transfer in prokaryotes ◦ Ex: E coli, staff, can become dangerous Eukaryotes Archaea Bacteria gene transfer • 1b3 so many genes were exchanged that early there tree of life may really have been a "ring of life" from which the 3 domains emerged • Prokaryotes have little internal structure ◦ Most individual species use a repertoire of 10-30 cmpds for energy ◦ Some are autotrophs; some are heterotrophs ◦ DNAis in a double-stranded single circular chromes located in nuclide region and in plasmids • Plasmids are small non chromosomal loops of DNA ◦ exchanged in horizontal gene transfer ◦ Can carry genes for antibiotic resistance ◦ Scientists use them as vectors to insert genes into Bacteria and Euk cell ◦ Prokaryotes have strong outer cell wall to protect against damage • Bacteria (but notArchaea) wall is made of sugar mols cross linked by peptides= peptidoglycan ◦ Any higher organism that breaks down glucose use bacteria like birds or cows ◦ Plant cell walls are made of cellulose • Some Bacteria andArchea wall stain purple with gram stain=gram positive ◦ Gram + have single thick wall that retains purple Gram stain ◦ The penicillin class of antibiotics block cross-linking of peptides to sugars in Gram+ Bacteria ◦ Penicillin works against Gram + Bacteria ‣ Walls without cross links are weak and rupture ◦ Antibiotics using the mechanism don't work with Gram- Bact orArchaeas (Archs aren't human pathogens) ◦ Many symbiotic bacteria are Gram- ‣ Live in stable conditions, don't need strong wall ‣ Ex: E.Coli in mammal guts ◦ Instead have 2 membranes: 1 inside wall; 1 outside wall ‣ Outer membrane of Gram- bacteria prevents penicillin from getting to its cell wall ‣ Antibiotics for Gram - or penicillin resistant bacteria work by inhibiting bacteria metabolism; or protein or DNA/ RNAsynthesis • Cells have nucleus and other organelles ◦ 1.8-2.8 bya • Features of Eukaryotic Cell ◦ Has a nucleus containing most of its DNAin linear form in chromosomes ‣ Some of it is in mitochondria ◦ Has organelles structures that compartmentalize Euk cells and allow complex metabolism ◦ Most have cell walls, except animal cells • Plasma membrane is the covering or outer skin of cells ◦ acts as barrier, gatekeeper for movement in/out of cell ◦ Membranes cover organelles and divide cell into compartments ‣ Made of lipids and phospholipids ◦ Most common lipid in animal plasma is cholesterol (water resistant) ◦ Phospholipids have some properties as detergent. Water base ‣ One end is polar; other is non polar ‣ =ampipathic ?? ‣ Polar end can dissolve in H2O; non polar in oil ◦ In membranes are arranged as a bilayer sandwich ◦ 2nd configuration??? • Polar ends face water inside and outside of cell • Hydrophobic tails interact with each other • Nonpolars are hidden from water inside bilayer • Because middle is a thick, non polar, member is impermeable to most H2O solutions ◦ Such as amino acids, sugars, proteins, nucleic acids and ions ◦ But allows nonpolars to pass easily • Membrane proteins customize membranes ◦ Bilayer forms matrix; proteins perform specific functions ◦ forms channels that allow ions and water to pass in or out of cell ◦ forms transports to move impermeable molecules in or out ◦ Act as antennas for incoming signals ◦ act as enzymes ◦ extracellular parts uniquely identify cells ◦ attach a membrane to other cells or the cytoskeleton MovementAcross Plasma Membrane • diffusion is movement of molecules down their [gradient] ◦ [gradient] = concentration gradient ◦ non-polars diffuse through membranes; polars don't ◦ Movement of H2O down its [gradient] is osmosis ◦ ions cross membranes only through channels or transporters • Transporters are large member proteins ◦ move impermeable compounds from 1 side to the other ◦ Rate is saturable b/c # of transporter is finite • Facilitated transport moves import molecules faster down their [grandient] passive ◦ doesn't require NRG • Glucose enters muscle & fat this way ◦ insulin turns transport on • Active transport, like facilitated except uses NRG to move molecules up their [gradient] • Many compounds are too large to use channels or transporters ◦ These use endocytosis or exocytosis ◦ endoplasm membrane invaginates to form vesicles ◦ oxo vesicle fuses with plasma membrane and contents are exported • 3 types of endocytosis ◦ Phagocytosis: particular matter is engulfed ‣ Immune cells do this to viruses and bacteria ◦ Pinocytosis: extracurricular liquid is taken ◦ Receptor-mediated endocytosis- forming vesicle is lined with receptors for specific molecules ‣ cholesterol is endocytosed via HDL and LDL receptors What is HDL and LDL?? • Aquick test for diabetes is to test for glucose in urine. Early physicians would dip finger into urine and taste to see if sweet • Formation of urine begins with filtration of all molecules <5000 MW from blood into the kidney's pre-urine. However, in normal people no glucose appears in final urine b/c it is reabsorbed by kidney before it reaches the bladder • Why does glucose get into urine of diabetes? ◦ Kidney transporters are saturated with glucose and can't filter it at all Cytoskeleton • Euk cells have a skeleton made of 3 types of protein filaments ◦ actin- finest, forms long thin filaments ‣ Most abundant protein 10-15% of all protein in body ‣ Involved in cell movement and structure; muscle contraction ◦ Intermediate filaments- tough, fibrous structural proteins like keratin ‣ In brain cells these are tangled inALS and Parkinsons, ◦ Microtubules- largest; hollow form internal scaffold that determines cell shape ‣ Form spindle apparatus in cell division ‣ move villa and flagella ‣ Organelles and vesicles are moved along these ‣ Degenerate and tangle=neurofibrillory tangles inAlzheimer's disease and athletes with repetitive head trauma ◦ Head trauma in athletes can lead to progressive degeneration of brain (CTE= chronic traumatic encephalopathy) ‣ CTE causes intellectual and memory deficits, anger, depression, and earlyAlzheimers in player of contact sports • Ex: Kim McManon Organelles and Internal Compartments ◦ Endoplasmic reticulum is an extensive network of membrane ‣ Derived from plasma membrane ‣ Divides cell into compartments, forms assembly line for synthesis or breakdown of molecules; forms vesicles ◦ Rough ER is studded with ribosomes (=protein/RNAcomplexes that synthesize proteins) ◦ Smooth ER contains enzymes for lipid synthesis and carbohydrate metabolism ‣ Lots of cells that produce steroid hormones ‣ Lots of detoxifying tissue like liver that use smooth ER enzymes to breakdown toxic compounds ◦ Peroxisomes are enzyme filled vesicles made by ER ‣ Involved in fat breakdown and lipid synthesis GolgiApparatus (Or Bodies) • = stacks of membrane; derived from ER • Collects and modifies mols then packages them in vesicles and distributes them • Animal cells contain ~10-20 Golgi bodies • Plant cells have hundreds of Golgi • Proteins and lipids from ER go to Golgi to get carbohydrate or phosphate groups added Why?? ◦ Became -glyco lipids or proteins; phospholipids or proteins • Golgi are plentiful in secretory cells where they make vesicles for export • Golgi also make lysosomes (equivalent to vacuoles in non-animal cells) for its cells use ◦ Contain digestive enzymes that can break down most organic macromolecules ◦ WBCs kill bacteria, viruses, etc by putting them into lysosomes ◦ There are a number of lysosomal storage diseases (~50) such as Tay-Sachs ‣ Defective gene causes enzyme that breaks down a lipid to be absent in T-S, causing lipid to accumulate in neurons, leading to brain damage and death by age 5. Born with it. 1 in 30 Jews. Cure for TB??? ◦ Silicosis and asbestosis result from indigestible silica and asbestos fibers being trapped in lysosomes which they pierce and cause to leak ‣ enzymes leaking from lysosomes damage lungs Nucleus • has nuclear envelope that is 2 layers of membrane ◦ is continuous with and derived from ER • Are a # of big pores in envelope • Many proteins and smaller molecules can't pass ◦ allow 2 types of larger mols to pass ‣ proteins made in ribosomes and needed in nucleus ‣ RNAgoing from nucleus to ribosomes ◦ # of nuclear pores in varies with metabolic activity • Nucleus contains a nucleus ◦ = region on chrome where lots of rRNAis being made for ribosomes protein synthesis stations • Nuclear pores are made of ~50 different proteins ◦ Proteins are directed for import into nucleus by NLSs (nuclear localization signals) short sequences of amino acids ‣ Import and export are complex and require NRG ◦ Pore is positively charge so compounds passing through have to be negatively charged Mitochondria • Originated when proteobacteria entered Euks early ◦ Perform aerobic respiration for our cells. Breathing O2 for mito. ◦ ~ same size as these bacteria ◦ Mitos have own DNAwhich is circular like back ◦ Euk don't manufacture mitts; existing mitts fission like back Different Bacteria. Both produced by fission ‣ Control of fissioning is by nucleus • Aerobic conditioning increase # of mitts ◦ Browns fat is brown b/c of all of the mito • Metabolically active cells contain more mitos • Antibiotics that inhibit bacteria ribosomes inhibit mitos • Mitos don't have cell wall Organelles Unique to Plants • Chloroplasts arose from engulfed cyanobacteria ◦ Double outer membrane ◦ Have own genome, reproduce by fissioning • Plants have a large central vacuole that can be >75% of cell volume ◦ stores H2O metabolites, digestive enzyme, wastes ‣ Performs many function of animal lysosomes ‣ Provides H2O pressure (turgor) that keeps plants from wilting • Water does not transport it goes through osmosis • Glucose is an example of facilitated fusion • ions can go through channels or be pa Metabolism • 3 major types ◦ Photosynthesis=synthesis of organic molecules from CO2 and H2O using NRG from sunlight Plant Cell ◦ Catabolism=breakdown of organic molecules to obtain energy, materialsAnimal cell ◦ Anabolism= synthesis of organic molecules from materials and energy Plant Cell Glycolysis • Is the only type of metabolism that almost all living organisms perform ◦ All living organisms use oxygen in there metabolism is false ◦ Of existing metabolic pathways, glycolysis is the most ancient. Maybe. ◦ All living organisms can use glucose in their metabolism.Almost true. ◦ Enzymes for glycosides float free in the cytoplasm. True. • Is anaerobic= uses no O2 • All reactions occur in cytoplasm; none in organelles • Glycolysis is a series of 10 reactions • Essentially cuts glucose in half to produce two 3C molecules in pyruvate ◦ NRG required to makeATP fromADP is produced by breaking bonds • Inefficient because only 2 of 10 reactions produce enough energy to makeATP ◦ Glycolysis produces a net of only 2ATPs/glucose ◦ Average person needs 2000 cal/day ‣ =236 lbs of solidATP ‣ Only ~1.7 oz ofATP in body at any given time ‣ ATP has to be generated over and over • Oldest fossils on Earth discovered in 3.7 by old Greenland rock in 9/1/16 • Aerobic Respiration ◦ Pyruvate is actively transported into mitochondria ◦ Acetyl CoAenters the Kreb Cycle ◦ Its Hs are stripped off and carbons are breathed out as CO2 ◦ Fats and proteins can be converted toAcetyl CoAand run through Kreb Cycle Generation ofATPby Mitochondria • Mitochondria inner and outer membranes from 2 chambers • Krebs Cycle occurs in inner chamber • Proteobacteria are Gram- • It generates 2ATP by bond breaking like glycolysis • But mostATps are generated by energy extracted from Hs stripped out of acetyl CoAin Krebs ◦ Hs are picked up by carrier molecules: NAD or FAD ‣ NAD=VitB3 ‣ FAD= Bit B2 ◦ When extract H, we are extracting energy out of process • Taken to ETC (electron transport chain) an inner membrane ◦ Energy of Hs stripped off acetyl CoAresides in their e-s. ‣ These hi NRG e-s are used in ETC to pump H+s into outer chamber ‣ This builds a high concentration of H+ into mitochondria outer chamber ◦ Concentration force: H wants to go in ◦ High concentration of H+ and its charge create 2 forces that act to drive H+ into inner chamber (=chemiosmosis) • 1 force from concentration gradient • 2nd comes from + charges repelling ◦ But inner and outer membranes are impermeable to H+ ◦ Only place H+s can go in is at a special couple calledATP synthase • This enzyme harnesses forces driving H+ back into inner chamber to generateATPs ◦ CO2s clipped off in Kreb's cycle are treated out ◦ O2 that we breathe in and spent e-s combine with extra H+s left after pyruvate in dismantled to form H2O • Aerobic respiration provides extra 28ATPs after glycolysis yields 2 ◦ each H carried by NAD yield ~2.5ATPs ◦ Each H carried by FAD yields ~1.5ATPs • FADH produces fewerATP cuz of where its Hs enter ETC ◦ this is less than the theoretical yield of 28ATPs/glucose ◦ Glycolysis 4ATP+2NADH -2ATP to start 2ATP gain to cell • Krebs 2ATP from bond breaking + 6 NADH + 2 FADH2 • Because NRG had to be used to actively transport pyruvate,ADP, and PO4, and 2 NADHs from glycolysis into mitochondria • Mitochondria membranes are a bit leaky to H+s Fermentation • When muscles don't get enough O2, pyruvate undergoes fermentation=anaerobic metabolism ◦ It is reduced (has Hs added to it) to lactate ◦ Cuz pyruvate can't diffuse out of cells easily but lactate can ◦ Otherwise, pyruvate would build up and create product inhibition which would slow production ofATPs by glycolysis ◦ Yeast produce alcohol from pyruvate Photosynthesis • Chloroplasts perform photosynthesis ◦ using disk like structures called thylakoids ◦ a stack of which is called a granum ◦ Cytoplasm is called storm ◦ Chlorophyll is a pigment in most photosynthetic really similar to hemoglobin in structure • Is green because green is the only wavelength not absorbed by photosystems Photosystems • = linked arrays of cholrophylls that collect light energy ◦ Cyanobacteria evolved Ph II to be used in combination with Ph I. ◦ Ph II allowed them to get Hs from H2 O • Light absorbed by chlorophyll excites on e- is that routed to a reaction center chlorophyll that can export it to ETC • Ph II works 1st; makes onlyATP using an ETC (as in mitochondria) via chemiosmosis ◦ Pumps H+s inward across thylakoid membrane ◦ ATP is made as H+s move out throughATP synthase • At end of ETC, e- handed off to Ph I ◦ This e- has given up ~half its energy in ETC to makeATP ◦ Ph I absorbs light, boosts their e- to excited state again ◦ Energy from this excited state e- is used to make NADH from NADP and H+s • NADPH provides Hs needed to make organic molecules • Ph I also makes someATP cuz PH II can't provide all theATPs need to make glucose • Ph II gave Ph I an e- which is given to NADP (along with an H+) • Ph II how needs a replacement e- badly • It gets one by splitting H2O into H+s, e-s, and O2 • H+s go to chemiosmosis given to Ph I • e-s replace those given to Ph I • O2 is released as waste Calvin Cycle • = the reactions that make glucose • Calvin cycle uses 18ATPs, 12 NADPHs, 6 CO2 to make 1 glucose ◦ CO2 are run through cycle at one time ◦ Each CO2 is fixed by adding it to RuBP (ribulose, 5- diphosphate a 5C sugar ‣ Catalyzed by Rubisco (most common protein on earth) ‣ Essentially glucose is made by running glycolysis in reverse (occurs in storm) • Plants makes and storesATP Cell Reproduction • 2 types of cell division used by most Eukaryotes • Mitosis occurs when cell makes a copy of self • Meiosis provides gametes for sexual reproduction • Most Eukaryote cells have pairs of chromosomes- diploid ◦ Humans have 23 chromosomes ◦ Pair members have similar structures and are called homologs ◦ Gametes (sperm, eggs, spores, pollen) are haploid Life Cycle of a Cell • G1- Growth of cell to G0( working phase; most cells in body are G0) OR S phase where DNA/chromosomes replicate • S phase goes to G2 phase where chromosomes begin condensing; organelles replicate • Next phase is mitosis where parts duplicate in S and G2 are moved into 2 compartments • Next phase is cytokenisis- division of 2 compartments into 2 daughter cells • Interphase- chromosomes are diploid; not visible • In S phase, our chromosomes are replicated to produce 92 sister chromatids ◦ Sisters are attached at centromere ◦ # of chromosomes always= # of centromeres ◦ Kinetochore is a protein structure that forms during cell division and to which microtubules attach Mitosis • Mitosis begins when chromosomes become visible • 4 stages: propase, metaphase, anaphase, telophase= PMAT • Prophase: ◦ Chromosomes become highly condensed ◦ Transcription stops nucleolus disappears ◦ In animals, centrosomes move to opposite poles ◦ = organelles that organize spindle apparatus ◦ Nuclear envelope breaks down so microtubules can get to chromosomes ◦ Microtubules form spindle apparatus and attach to kinetochores • Metaphase: ◦ called the metaphase plate ◦ Near end of metaphase molecules holding chromatids together break down freeing sisters • Anaphase: shortest- few minutes ◦ Microtubules pull sisters to opposite poles and push against poles to stretch cell • Telophase- returns cell to interphase ◦ Chromosomes uncoil; transcription begins again ◦ Spindle apparatus is dissembled ◦ Envelope reforms around each new nucleus • Cytokenisis- physical division of cell into 2 parts after telophase ◦ By contraction of belt of actin/myosin filaments which forms a cleavage furrow (in cells without walls) ‣ Can't do this in plant cell because of cell wall • Plants build new cell membrane and wall b/w daughters • Fusion of haploid gametes produces a new diploid cell=fertilization or syngamy ◦ Offspring carry traits from both parents Mitosis vs. Meiosis • Mitosis and meiosis begin the same the chromosome duplication in Interphase • PMAT stages in Meiosis 1 are called P1, MI,AI, TI • In Mitosis duplicated homologs line up individually along the metaphase plate • In Meiosis I, duplicated homologs pair during PI and stay paired along metaphase plate during MI • In anaphase of mitosis, each chromatid of a homolog is pulled to a different pole • InAnaphase I of mitosis, each duplicated homolog is pulled to a diff pole • In humans, Meiosis I produces 2 new cells with 23 chromosomes/23 centromeres ◦ Each chromosome is 2 attached sister chromatids • Meiosis II performs mitosis on cells produced by Meiosis I • Pairing of homologs in PI= synapsis ◦ Genes from each chromosome are aligned side by side by the synaptonemal complex ◦ Crossing over between chromatids exchanges corresponding sections of DNA • In humans, 2-3 crossing overs occur/ charm pair resulting in non-identical sister chromatids • In Mitosis, kinetochores are on opposite sides of centromere; in Meiosis I, kinetos of each homolog pair face the same pole ◦ Pulling paired homologs apart inAI , therefore 2 chromatids and their centromere go to each pole • At beginning of Meiosis, egg and sper, precursors have 2 copies of the 23 chromosomes ◦ This can produce 2^23 or 8 million possible gametes ◦ Fertilized egg is from 2 gametes and has 64 trillion possible permutations (8 mill * 8 mill) ◦ Crossing over further increases variability to mind boggling degree ◦ And allows genes from mom and dad to end up on some chromosomes


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