AP Biology Chapter 18 Flashcards
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| 6234430390 | Operator | -off/on "switch" that controls whole cluster of functionally related genes -segment of DNA that provides coordinate control -positioned within promoter OR between promoter and enzyme coding genes -controls access of RNA polymerase to genes |  | 0 |
| 6234430391 | Operon | -operate + promoter + genes they control -entire stretch of DNA for enzyme production for tryptophan pathway Operon not switched off permanently b/c: 1. binding of repressors to operators is reversible 2. trp repressor is an allosteric protein w/ 2 alternative shapes: active and inactive |  | 1 |
| 6234430392 | Repressor | -protein that switches operon off -binds to operator and blocks attachment of RNA polymerase to promoter -specific for operator of particular operon |  | 2 |
| 6234430393 | Regulatory Gene (trpR) | -product of trp repressor -located some distance from operon it controls -has own promoter -expressed continuously at low rate | 3 | |
| 6234430394 | Corepressor | small molecule that cooperates w/ repressor protein to switch operon off |  | 4 |
| 6234430395 | Repressible Operon | transcription usually on but can be inhibited when specific small molecule binds allosterically to regulatory protein |  | 5 |
| 6234430396 | Inducible Operon | transcription usually off but can be stimulated when specific small molecule interacts w/ regulatory protein |  | 6 |
| 6234430397 | Inducer | specific small molecule, inactivates repressor | 7 | |
| 6234430398 | Cyclic AMP | small organic molecule which accumulates when glucose is scarce | 8 | |
| 6234430399 | Activator | protein that binds to DNA and stimulates gene transcription (ex. CAP) |  | 9 |
| 6234430400 | Differential Gene Expression | expression of different genes by cells in the same genome |  | 10 |
| 6234430401 | Histone Acetylation | -acetyl groups (-COCH3) attached to lysines in histone tails -> lysines acetylated -> positive charges neutralized -histone tails no longer bind to neighboring nucleosomes | 11 | |
| 6234430404 | Epigenetic Inheritance | inheritance of traits transmitted by mechanisms not directly involving nucleotide sequence | 12 | |
| 6234430405 | Control Elements | segments of noncoding DNA that help regulate transcription by binding certain proteins | 13 | |
| 6234430406 | Enhancers | -distal control elements -may be thousands of nucleotides upstream/downstream of gene or in intron | 14 | |
| 6234430408 | Alternative RNA Splicing | -different mRNA molecules produced from same primary transcript, depending on which RNA segments are treated as introns and exons -can expand repertoire of eukaryotic genome | 15 | |
| 6234430409 | Proteasome | giant protein complex recognize ubiquitin-tagged proteins and degradation 1. multiple ubiquitin molecules attached to protein by enzymes in cytosol 2. ubiquintin-tagged protein recognized by proteasome, unfolds protein and sequesters it within central cavity 3. enzymatic components by proteasome cut protein into small peptides-can be further degraded by other enzymes in cytosol |  | 16 |
| 6234430410 | microRNAs (miRNAs) | -small, single-stranded RNA molecules capable of binding to complementary sequences in mRNA molecules 1. enzyme cuts each hairpin from each primary mRNA transcript 2. dicer enzyme trims loop and single-stranded ends from hairpin-cutting arrows 3. one strand of double stranded mRNA degraded; other strand (miRNA) forms complex of 1+ proteins 4. miRNA in complex can bind to any target mRNA that contains at least 6 bases of complementary sequence 5. if miRNA and mRNA bases complementary along length, mRNA degraded; if match less complete, translation blocked |  | 17 |
| 6234430412 | Small Interfering RNAs (siRNAs) | -similar in size and function to miRNAs -formed by much longer double-stranded RnA molecules -> many siRNAs | 18 | |
| 6234430413 | Cell Differentiation | process by which cells become specialized in structure and function | 19 |