Most regulation is during initiation step of RNA synthesis. When RNA is being
transcribed, transcription factors in EUK will look for the TATA box and recruit RNA
POL. Most TFs are homodimers; they can either be positive or negative.
Positive recruits RNA pol
Negative blocks promoter
TF binding sites in PROK ARE CALLED OPERATORS, A NEGATIVE TF WILL
SHUT OFF EVERYTHING.
E. COLI TRP OPERON… the mRNA produced will have 5 different reading
frames… forming 5 proteins. If there is a Trp Repressor protein bonded to the
OPERATOR SITE; then NO RNA IS MADE, because the promoter is taken off; blocks
RNA from doing it’s job. The negative tf is tryptophan.
Promoter – Operator0 trpE trpD trpC trpB trpA uses RNAPOL
When tryptophan is absent the reaction proceeds forward making more trp proteins.
Some TF’s are very specific, 1tryptophan is responsible only for trp operon… others
regulate only a few genes.
HBB of betaglobin gene is regulated by EKLF. When EKLF binds, more beta globin
will be made.
Eklf is before the promoter site… uses RNA pol 2.
Positive TF when glucose high
Negative TF when glucose low
Insulin gets rid of blood glucose!
TRPV6 OR CAT1 GENE REGULATED CALCIUM ENTRY INTO THE CELL;
NEEDS VITAMIN D TO WORK. VDR IS A POSITIVE TF THAT WILL PROMOTE
IF POSITIVE, THE OPERATOR SITE IS BEFORE THE PROMOTER SITE . IF YOU
HAVE TOO LITTLE CA++ YOU HAVE TOO LITTLE CALCIUM TO MAKE HARD
BONES. YOU NEED 1000 UNITS A DAY.
Genes are regulated because they make stuff on what’s needed and depend on nutrients.
Housekeeping genes are always on, like glycolysis processing enzymes.
Regulated genes depends on what’s there… if there’s lactose (food) increase in lac
Genes in each cell have to regulated so a heart cell does its stuff. Each cell has
21,000 proteins, but in the stomach only 6537 are on… vs 9379 in the heart. Both have
housekeeping genes ALWAYS ON. MUTATIONS MEANING EXAMPLE
Changes in DNA sequence
Can be obtained in lifetime
or passed on from
generation to generation
Mutations in the ORF ▯ Mutations within the genes
affect functional ability ofare mostly in the ORF…
gene not so much of a big deal in
the 3’ or 5’ UTR
SILENT No effect on the protein Yo