The 60-mm-diameter shaft is made of 6061-T6 aluminum. If the allowable shear stress is tallow = 80 MPa, and the angle of twist of disk A relative to disk C is limited so that it does not exceed 0.06 rad, determine the maximum allowable torque T.
Study Guide for Midterm #2 Bio 151 RNA World Hypothesis -RNA system that replicates in two steps 1. Self replicating RNA 2. RNA acted as a template for forming 3. Proteins then aid in replication of RNA 4. Make DNA from RNA for storage of info -Problems: Clutter with other molecules, efficiency of ribozyme Prokaryotes most likely came before Eukaryotes -Prokaryotes infolding of membrane to make nucleus Endosymbiont: theory for semiautonomous organelles -organisms living together in direct and intimate contact -mitochondria and chloroplasts both contain small amounts of circular DNA Nucleus: contains chromatin and nucleolus -chromatin: strands of chromosomes -nucleolus: sit of rRNA synthesis, assembly of large and small ribosomal subunits -nuclear envelope: 2 lipid bilayers -inner and outer nuclear envelopes perforated by nuclear pores Movement of vesicles: by being attached to elements of cytoskeleton: intracellular rods and fibers that support cells or by motor proteins Microtubules: thickest -helical polymer made of individual dimers of a and b tubulin proteins -can be stable girders, but also move things -push or pull, move things using attached motor proteins -sliding, move cilia and flagella -cilia and flagella contain m.t. organized into ring, pairs connected by dynein -basal body: specialized centriole at base of every cilium or flagellum Endosome: membrane wrapped vesicle Centrosome: microtubule organizing center Microfilaments: finest -double helix made of actin proteins -shortened or lengthened by removal or addition of actin -slide using motor proteins like myosin Intermediate filaments: middle -structural meshwork to shape -coat proteins help shape and traffic membranes Prokaryotic cell division -fission, one circular chromosome replicates then splits Chromatid: 1 DNA double helix, two sisters connected by centromere Chromosome: depends on number of DNA double helix Mitotic spindle: arranges and moves chromosomes Mitosis: phases -interphase: duplicating chromosomes -prophase: two of each -metaphase: line up -anaphase: separate -telophase: two new cells Kinetochore: proteins surrounding centromere control movement Cytokinesis: subdivision of the cytoplasm into two cells -animal cells: cleavage furrow -Plant: cell plate Cell cycle -G1 between m and s -S: dna replication -G2: between s amd m -M: mitosis/division Checkpoints -G1: cell large enough, nutrients, signals -G2: happy, dna duplicated -M: chromosomes attached to cytoskeleton for movement MPF: complex of two proteins that drives cell through g2 check point -CDK to create active MPF Meiosis: makes half the number of chromosomes -makes gametes, diploid (2n) into haploid (1n) -Homologues: can have same genes but different versions -Meiosis I: meiotic spindle lines up homologous chromosomes next to each other, separates, sister chromatids stay together -crossing over may happen at chiasma -II: halves amount of DNA, sisters separate Phenotype: physical trait individual has Genotype: genetic info that is passed Homozygous: alleles on both genes are identical (AA or aa) Heterozygous: alleles are different (Aa) Dominant control, recessive only if both alleles Mendel’s Law of Segregation: the two alleles in the parent segregate from each other during formation of gametes Incomplete dominance: heterozygote has phenotype that is intermediate between that of homozygotes Codominance: different alleles give difference dominance traits so both show There can be sex-linked complication Nondisjunction: errors of chromosome separation during meiosis One gene is silenced Respiration 1. Glycolysis: only in cytoplasm, 6 C glucose lysed into 2 3C pyruvates gets 2ATP and high energy e-, 2NADH 2. Intermediate Cycle 3. Krebs Cycle: pyruvates enter in mitochondrial matrix, broken into CO2, get 2 ATP 4. Oxidative Phosphorylation: mitochondrial membrane, high energy e- + O 2 ATP -need a pool of NAD+