Final Exam
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (19 张)
What are the 4 components in the role of DNA?
Replication Transcription Translation DNA repair
what does the sigma factor do?
directs the RNA polymerase core enzyme to a promotor
what is rho-dependent transcription?
rho protein follows RNA polymerase and removes it when it reaches the termination sequence
what is rho-independent transcription?
hair-pin loop forms in RNA which causes RNA polymerase to remove itself
Brief explanation of translation in bacteria
small ribosomal subunit and Shine-Delgarno sequence align machinery to correct location. Multiple Shine-Delgarno sequences allows bacteria to be polycistronic
two environmental factors that effect regulation
• changes in nutrients and availability - changes in competition
what are two constitutive processes in the cell (housekeeping genes)
TCA cycle and ATP synthases
when can gene expression be controlled?
transcription, translation, post-translation
what are the 4 types of covalent modification?
alters enzyme conformation: • phosphorylation • acetylation • methylation • glycosylation
describe allosteric inhibition
the final product of a pathway often inhibits the activity of the enzyme in the first steps of the pathway. the product may bind to the enzyme and change its conformation so that it can no longer bind to the active site. inhibition or activation is possible through this process
what is an operon?
a transcriptional unit with a series of structural genes and regulatory elements
parts of the lac operon
• lacI: repressor • promotor • operator • lacZ: beta-galactosidase • lacY: permease • lacA: transacetylase
allosteric in positive control
activates mRNA synthesis
allosteric in negative control
prevents mRNA synthesis
what is attenuation
interruption of transcription after initiation but before termination
explain attenuation
• interaction between translation and transcription • if ribosome quickly follows RNA polymerase, hairpin loops are formed in the leader sequence and the polymerase detaches • “stalling out” of ribosome (ex. not enough amino acid in tRNA) • does not occur in eukaryotes
what is quorum sensing?
chemical signalling system that allows microbes to communicate with each other. it is regulated by population density
what are the two example organisms in quorum sensing
Hawaiian bobtail squid that has vibrio fisheri in its light organ
how do vibrio fisheri produce light?
• when in high density they produce N-acyl-homoserine lactone (AHL) which stimulates luminescence • luxI protein catalyzes AHL synthesis • luxR (regulator transcriptional activator) interacts with AHL in high concentration • binds the lux box DNA regulatory site • leads to transcription of luciferase protein genes and luxI, which creates positive feedback loop forming more AHL