THEME 3 MOD 1 Flashcards
(12 cards)
How are gene regulation and environmental conditions connected?
environments undergo changes where a cell may need to adapt by regulating certain genes
labratory aerobic environments
culture media with amino acids, vitamins, nucleotides, and carbohydrates
housekeeping gene
Kept “on” at all times /required all the time for normal/regular functions and cell maintenance
include genes of structural proteins, DNA and RNA polymerases, Ribosomal proteins
regulated genes
turned on/off as needed
expression patterns of these genes are altered when an environmental change is encountered
(bacterial regulated genes) can be transcribed and translated to produce proteins and enzymes needed to bring about changes in cell growth/development
enzymes for metabloism
Enzymes are required to metabolize energy sources, including carbohydrates/ macromolecules into cellular fuel in ATP
E coli bacterial cells using gene regulation in prefered energy sources
glucose is the preferred energy source
when depleted, bacterial growth is arrested
can use a gene regulation mechanism to switch to metabolizing alt energy source (lactose)
glucose metabolism products activate switch to metabolizing lactose
because lactose is only metabolized when available, and there is no glucose, it would be wasteful to always synthesize enzymes that metabolize lactose
What enzyme is transcribed and translated and modified only when lactose becomes the energy source
beta galactosidase gene is quickly upregulated when lactose becomes the only energy source (glucose is absent) to produce the enzyme beta galactosidase
why can lactose be used for cellular energy
Lactose is a disaccharide containing to monosaccharides: glucose and galactose. beta galactosidase breaks lactose into these two monosaccharides
what was significant about the research of jaques monod and francois jacobs
investigated gene regulation of b-galactosidase in e coli bacteria cells
-enzyme production dependant on lactose presence, increases steadily upon lactose precence, ceases when lactose removed
- measured this by growing colony in lactose free medium, the introduced lactose, then took it away and evaluating the expression of b-galactosidase during each interval
gene regulation
gene is transcribed, translated, protein is modified
- protein is made, activated and modified
3 controls/regulations for gene expression
transcriptional control:
- mrna from dna
- controls amount of mrna in cell
- proteins binding to promoter region and recruiting rna polymerase turn the process on and off
translational control:
- ribosome must bind to promoter or shine-dalgarno region of mrna for translation to occur
- rate of translation and stability of mrna effects amount of proteins produced
post translational control: whether protein becomes active or inactive
- addition/removal of post translational modifications
- polypeptide chain has to be made into active protein by mechanisms that allow protein folding
- other post translational controls: driving assembly into complexes, substrate binding, unmasking enzymatic domains
which regulation in the fastest? slowest? most economical?
post translational regulation is the fastest as cells can stockpile inactive proteins and use a simple modification mechanism to activate them. these modifications are quick, lead to fast cell responses
transcriptional is the slowest, because the cell has to start from scratch and activate to transcribe, translate, and modify protein products. used in drastic environmental changes (eg b- galactosidase expression, delayed response by e coli cells).
transcriptional regulation is also most economical as cell doesn’t use energy/resources, can be expressed on as per needed basis
