Lecture Notes For Exam 2.docx

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Biological Sciences Program
BSCI 207
Steve Kent

2/24 Extremophiles - modifications to membrane phospholipids (amphipathic - polar and nonpolar) - saturated - all single bonds (warm, more porous) - unsaturated - mixture (cold, more rigid) - degree of saturation alters properties -animals can adjust the rigidity of membrane, to make more porous when warmer - ether linkage chemically stronger than ester linkage (extremophiles - ether) - cross linking (?) - archaeans have transmembrane phospholipids Prokaryotes - different forms of diversity - prokaryotes - very high metabolic diversity, very low structural diversity - eukaryotes - low metabolic diversity, very high structural diversity - prokaryotes generally much smaller than eukaryotes - 10x more prokaryotic cells than eukaryotic but eukaryotic bigger - comamonas - metabolize testosterone - chemiosmosis - ATP generated when protons pumped out to create a gradient, osmosis wants to pump them back in, store energy - photosynthesis - 1: makes NADPH, 2: makes ATP - simple photosynthesis - cyclic and noncyclic photophosphorylation with 2 complexes - old system, nothing good enough to replace it - early electron transport chain, modified a thousand times - bioremediation - using life to fix a problem (chemical or pollution problem) - use prokaryotes to break down harmful chemicals into safer compounds - find naturally occurring bacteria or use artificial selection - metals - makes insoluble so can’t get into water - mining - oxidizes them to make soluble 2/26 Origin & Diversity Of Unicellular Eukaryotes - more complex cells = complex redundant genome, high level of internal specialization, efficient at multi tasking - evolution of larger cells = control more resources, cell specialization - urkaryote - cell with defined nucleus but does not have organelles characteristic of eukaryotic cells (anaerobic and heterotrophic) no mitochondria, no plastids - why nuclear membrane? selective permeability, DNAnot stable, protection from water (phosphate groups have strong negative charge and water molecules are going to form around to make a hydration shell - interfere with stability of the helix) provides structure to entire interior of cell - prokaryotes without nucleus? stay small - only have a little bit of DNA, hydration shell not a big issue. or have a double membrane around nucleoid (nucleoid envelope and plasma membrane) largest prokaryotic cell with largest genome - transcription occurs in nucleus with mrna, makes protein in cytoplasm (decoupled transcription and translation) - in prokaryotic cells, transcription and translation simultaneous - planctomycetes - coupled and decoupled transcription (independently evolving same structure as eukaryotes) - archaean and bacterial cell fused their genomes = more complex nuclear mass - endosymbiosis - anaerobic urkaryote + aerobic bacteria - independent replication (mitochondria divide independently of the nucleus) - simple genome (1-4% bacterial genome) circular DNA, coding sequences, no histones - transcription and translation - prokaryotic (70s ribosomes) mitochondria susceptible to antibiotics - systemic inflammatory (sirs) - a proteobacteria (genes we have in mitochondria are closer to a proteobacteria than to us) - bacterial control genes to nucleus (why? genes better protected in nucleus and produce larger amounts of protein faster) - increased efficiency of cell, long term benefit to mitochondria as well - plastid - photosynthetic organelles in eukaryotes (resemble prokaryotes in size, shape, internal membrane structure, pigments, ETCs,ATP synthase) - 5-10% of cyanobacteria in plastid genome - same transfer of genes between plastids and nucleus and mitochondria and nucleus - 8 major lineages of eukaryotes - all protist plastids use chlorophyll a in reaction centers (oxidize h2o to generate o2, H+, and e-) - different plastids use different antenna pigments - glaucophytes - photosynthetic, eukaryotic, double membrane around chloroplasts, peptoglycan wall between membranes - primary endosymbiosis - plastid arose from prokaryotic ancestor - evidence that mitochondria in cells before plastids (cells with mitochondria but no plastids, no cells with plastids but no mitochondria) - red and green plastids closely allied with blue green plastids - red has 2x as many genes as green, encode similar processes, almost identical transport proteins - problems - cryptomonas = 4 membranes around plastids, persistent nucleomorph, transfer of most photosynthetic genes from nucleomorph to host nucleus, one set of 70s and 2 sets of 80s (prokaryotic and eukaryotic) - secondary endosymbiosis - photosynthetic eukaryote captured and evolves into organelle - protist evolutionary innovations - large size = major changes to extensive cytoskeleton - compartmentalization (nucleus, organelles, internal membranes) - mitosis = somatic growth - sexual reproduction - meiosis and syngamy - alternation of generation - allows for 2 major growth stages and get resources from environment - coloniality and multicellularity, enhanced motility, ingestive feeding 2/27 Scaling of Function - reasons for shape change - physical constraints (change in size) or different functions (change in lifestyle) - scaling of body plans - model organisms as simple cubes (length L, cross sectional area L^2, volume L^3) - strength - proportional to cross sectional area - mass - proportional to volume - volume increases faster than area - at some point area will no longer be able to support mass and collapse under its own weight (cube has reached critical size based on nature of material forming structure) - large size limits shape - eukaryotic - larger, more complex, less metabolically efficient - scaling - - y = ax^b - log y = log a + b(log x) a = y intercept, b = slope - slope of line is ⅔ because numerator is to the second power and denominator is to the third power (geometric similarity) - isometry - organismal shape exhibits geometric similarity (but most relationships in organisms are allometric) - allometric scaling allows organisms to reach larger sizes (could alter shape = same volume but different surface area) new combination of properties can be exploited by organisms - most scaling organisms have slopes that are multiples of ¼ not ⅓ - supply demand dynamics - transport in directed systems B=m(rs/rd)^9D/(D+1) - B = metabolic rate = m^(¾) - m = mass - rs = supply rate - rd = demand rate - D = dimension - complex transport systems - - fractal geometry - techniques for analyzing complex shapes (?) - measurement - M = ns^d (measurement = # of steps x step length to the dimension power) - d = 1 length, d = 2 area, d = 3 volume or mass - 1
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