Lac Operon (13.3) Flashcards
Gene expression
process that heritable information in a gene is made into a function gene product, such as protein or RNA
Gene regulation
the process of controlling gene expression. The mechanisms of gene regulation can occur during any part of gene expression
This includes transcription, RNA processing, translation or post-translational modifications
What molecules are involved in gene regulation?
Activators, inducers, repressors, co-repressors, operators, and regulatory sequences
Regulated promoters
promoters that allow for transcription only when certain conditions are met
Why do organisms regulate gene expression?
Different organs and tissues need different proteins
Different genes are needed under different environmental conditions
Transcripts and proteins take up space
Constitutive gene expression
expressed all the time, at constant levels
What are some genes that an organism might want to always be expressed?
RNA polymerase, ATPase, Ribosomes, RNAs, Histone, tRNAs, DNA repair enzymes, Oxphos complexes, Cell cycle enzymes and Proteosome
What are 3 ways to regulation gene activity?
transcriptional, translational and post-transitional
Operator
DNA sequence region that lac repressor can bind to
lactose, no glucose
high levels of transcription
CAP: bound
LacR: unbound
lactose and glucose
medium transription
CAP: unbound
LacR: unbound
no lactose, no glucose
No transcription
CAP: bound
Lacr: bound
No lactose, glucose
No transcription
CAP: unbound
Lacr: bound
Negative regulation
When binding of regulatory protein to DNA blocks transcription
Positive regulation
When binding of a regulatory protein to DNA activates transcription
Activator
regulatory protein that promotes gene expression
Repressor
regulatory protein that prevented gene expression
Inducer
a small molecule that promotes gene expression
Co-repressor
a small molecule that prevents gene expression (typically works with a repressor)
Signaling molecule
a small molecule that transmits signals to regulatory systems (cell communication
Regulatory sequence
sequences on DNA/RNA that control gene expression
Leaky expression
some vasal, very low level of expression
