Lecture 12 : Gene Expression

Question 1

Housekeeping genes, Specialised proteins

Question 2

Notes about genes

Answer 2

• Not all genes expressed at same rate, can be abundant or scarce
• Genes can either be constitutively expressed (always on), or conditionally expressed (always off)
• Most cells express 10000-15000 genes

Question 3

What is the predominant level of gene control

Answer 3

Translation

Question 4

Transcriptional control

Answer 4

mRNA population regulated by :
- Which genes are transcribed
- Rate of transcription
- Transcriptional start site used

Question 5

Regulating gene expression by RNA processing

Answer 5

• Splicing (removing introns)
• Capping (addition of 5’methyl cap)
• Polyadenylation (Adding 3’poly(a) tail

Question 6

What is Poll II

Answer 6

• Site of capping
• Site of splicing
• Site of adding poly(A) tails
• Splicesome complex

Question 7

Why do we have introns

Answer 7

• Important in molecular evolution (exon shuffling)
• Allow for alternative mRNA splicing

Question 8

Splicesome

Answer 8

• snRNPs are large ribonucleoprotein complexes containing ribosomes
• Site of splicing
• SRSFs can inhibit splicing

Shits spliced for a reason