Cellular Communication Flashcards
(21 cards)
Gene expression can be regulated at certain points, what is the most common point of regulation
translation
why is regulation of transcription more efficient than other processes
It conserves the most energy, and time
Where does gene expression begin
The promotor
What is the role of the promotor
It is the site of transcription factor binding and RNA polymerase is recruited, to initiate transcription
How can some genes be activated while others are left inactivated
Selective gene transcription
What are the two types of regulatory proteins that can bind to DNA
Repressor proteins
Activator proteins
What do Repressor proteins do
repressors have a binding sites on DNA and prevent transcription happening on the sequence after the repressor
what is a Positive regulators
a positive regulator has an activator binding site and when bound causes a gene to be “switched on”.
Can an RNA polymerase find a promotor on its own
No, RNA polymerase cannot find promotors on its own.
What is a sigma factor
Core promotor element variants recognised and bound by specific sigma factors
what happens when a sigma factor bind to RNA polymerase
they form a holoenzyme complex, which can recognise and bind to specific promotors on the DNA
Do ‘strong’ promotors initiate transcription more or less frequently than ‘weak’ promotors
the stronger the promotor the more frequently the transcription will happen.
Will one sigma factor produce a single or multiple transcripts, if multiple roughly how many
4 sigma factors can produce roughly 100 transcripts.
Name the three proteins involved in uptake and metabolism of lactose
Beta-galactoside permease
Beta-galactosidase
Beta-glactoside transacetylase
in the presence of glucose, will prokaryotes produce lactose conversion enzymes
No as it would be a loss of energy as the lactose conversion enzymes are not required to break down glucose
What are the two ways to regulate a metabolic pathway
- Allosteric regulation of enzyme - catalysed reactions allow rapid fire tuning
- Regulation of gene expression is slower but conserves more energy
What are the two methods of enzyme activity regulation
- Negative feedback loops, the products feedback info
- Regulation of enzyme concentration, the end product blocks the transcription of all the genes, and no enzymes are produced.
What is an operon
a cluster of genes with a single promotor thats transcribed together into a single mRNA is an operon
what do operons do
allow for coregulation
what is contained in a typical operon
a promotor
two or more structural genes
an operator
What are the three ways to regulate transcription on prokaryotes
- an inducible operon regulated by a repressor protein (default is off)
- A repressible operon regulated by a repressor protein (default is on)
- Operon regulated by an activator protein (default is off)
