bio midterm review

bio midterm review - BIO301M midterm review Homology vs...

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BIO301M midterm review Homology vs. Analogy – o Homologous structures serve different functions; may have been produced by morphological divergence from the body form of a common ancestor; good comparative morphology (bats and humans arms) o Analogous structures serve similar functions; individuals undergo morphological convergence where different lineages evolve in similar ways under similar environmental pressures; noise comparative morphology (bird and bee wings) Blood problem – o In codominance, a pair of nonidentical alleles affecting two phenotypes are both expressed at the same time in heterozygotes o I A and I B are codominant when paired o i is recessive; a pairing with either of the two codominants masks its effects o If you have I A I A or I A i , your blood type is A; if you have I B I B or I B i , your blood type is B o With codominant alleles I A I B , it’s AB o Homozygous recessive, ii , glycolipid molecules never get a final sugar side chain, so your blood is O Cell organelles – internal compartments o Plasma membrane: Thin, outermost membrane that maintains a cell as a distinct entity Lets metabolic events proceed in controllable ways, separated from outside environment; yet, does not isolate cell interior Water, oxygen, and carbon dioxide cross in and out freely Other substances, such as nutrients and ions, get escorted across o Mitochondrion Much-folded inner membrane divides the interior of the mitochondrion into two compartments Hydrogen ions released from the breakdown of organic compounds accumulate in the inner compartment by operations of transport systems As they flow back to the outer compartment, they drive the formation of ATP ATP-forming reactions of aerobic respiration end here
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All eukaryotic cells have one or more mitochondria Cells requiring a great deal of energy may contain thousands or more o Chloroplasts Important plastid that only photosynthetic eukaryotic cells have Has two outer membranes around a semifluid interior, the stroma, which bathes an inner membrane Often, this single membrane is folded back on itself as a series of stacked, flattened disks, called a thylakoid Embedded in thylakoid membrane are light-trapping pigments, including chlorophylls, as well as enzymes and other proteins with role in photosynthesis Proteins – chain of amino acids held by peptide bonds o In gene transcription, a sequence of exposed bases on one of the two strands of a DNA molecule serves as a template. o Using that template, RNA polymerase assembles a single strand of RNA from the four ribonucleotides, A, U, C, and G. o Before leaving the nucleus, each new mRNA transcript, or pre- mRNA undergoes modification into final form. Only mRNA carries DNA’s protein-building instructions from
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bio midterm review - BIO301M midterm review Homology vs...

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