Two types of genes
Constitutive genes
Inducible gene
Constiuitive genes
Always expressed
Not regulated
Inducible genes
Highly regulated
Induced or repressed
Why regulate gene expression
conserve resources
respond to chnages in external/internal environment
Orrdered development ( of cell wall)
do eukaryotes couple transcription and translation together
Yes,
mRNA is degraded whilst translation
what are operons
Co transcribedd genes
Single regulalated promoter
transcriped from operons are synthesized as polycitronic mRNA
Polycistronic mRNA
Single mRNA with multiple genes
All gened transcrioed together
Multiple proteins form
Usually have related function
Genes in operons always have related function
T/F
FALSE
they sometimes have related function
Why do genes in opersons have mostly related function
allows forr regulation of muktiple genes in sam pathway from a single promoter
Non coding proteins
Transcriped but not translayted
eg of non coding proteins
trna
rrna
CRISPR rna
Name the bacterial ncRNA protein that targets invading viruses/ genetic elemets
CRISPR CAS-
What two proteins do cas9 interacts w
crRNA and tracrRNA
Function of crRNA— ie CRISPR RNA
Contains sequence that matches viral dna
function of tracrRNA
Helps cas9 bind to crRNA and activate cutting
CrRNA + cas protein
Has sequence of virual genome from memory — looks for that sequeence to kill
Viral dna is a spacer
Bacterium inserts spacer (memory) into crispr cas
ONE SAME virus attack crispr cas (+ spacer) is reasdy
how does crispr cas recognise invading dna
nucleotide complementary
Q: What is the primary function of the CRISPR‑Cas system in bacteria?
defence system where bacterial ncRNA guides Cas proteins to recognise and cut invading viral DNA.
What components make up the bacterial CRISPR‑Cas complex?
Cas protein (e.g., Cas9) + crRNA + tracrRNA (or engineered sgRNA).
What is cRNA
A: A short RNA containing a viral sequence (“spacer”) from past infection that guides Cas proteins to the matching viral DNA.
WHAT IS tracRNA
An RNA required for Cas9 activation and for stabilising the crRNA–Cas9 complex.
What are the three stages of CRISPR‑Cas immunity?
- Adaptation (spacer acquisition) 2. Expression (crRNA production + Cas complex formation) 3. Interference (targeting and cutting viral DNA)
