Alternative splicing
Removal of introns 3 joining exons
>
-
trans esterification > Lariat
-
intermediate
Nucleophilic attack & S' end >
-
forms loap
cleared
Another nucleophilic attack & 3' end
be removed too
> exons
-
may
SPLICEOSOME
snRNPs
/
3 00 other proteins
end
&
u, ps
>
-
Recog intron exon boundary Other
conserved regions each contains
ve end a bind first sing le short
RNA Molecule
VL
U 3 Recruited
then 13 4 are released
which activates the spliceosome
Binding tightly Regulated
is
>
spliceosome only recognises real introns
-
with
highly conserved motifs
S
5' GU
Essential 31 AG
↳ upstream pyrimidine sequence
Ccytosine 3 uracil
Branchpoint site >
-
Ademine for nucleophilic attack
SR proteins promote binding (Ser & Arg rich splicing fastors
Regulation - of U1 and U2 SMRNPs
Bind to enhancers Si 3
S
I
31
·
in sxons (ESE) -
or intron
sequences [ISE)
Stabilise
·
binding
·
encourage binding
cleared
cleared
*
-
hnRNPs bind to
splicing
suppressors in exons (ESS)
or introns (ISS) and inhibit
, Reverse transcriptase PCR 3 Northern Blotting
RcDNA Synth
isolate
1) MRNA
make use of
poly A tail
RT 3 poly T- > CDNA
2) standard PCR
add RNAse to degrade mRNA
left with SSCDNA
·
primers
Tag Pol .
·
SEX RETERMINATION IN INSECTS
Ratio of X: Y determined sex not active Y
Mechanism in drosophila
X = male
XX = female
no .
of X chromosomes determined by expression
level of 4 X linked genes 33
encode
TFS
S 3
scule All bind to
-
Sisterless promoter of Sex lethal Binary
mmt
gene
-
unpaired Sfourth) encodes a ligand that SX/
activates
maternally supplied TF
a
After 14th nuclear division formation of individual cells
4 scute , sisterless ,
mut b unpaired turned off forever after 14th
division
Sxl
In order to
getbindexpression of need cons of
proteins to to b
promoter activate
X will reach first because 2 copies :
2 protein conc .
-
proteins degraded after 14th
XY = fernale because in haploid
takes longer >
-
15th division
Removal of introns 3 joining exons
>
-
trans esterification > Lariat
-
intermediate
Nucleophilic attack & S' end >
-
forms loap
cleared
Another nucleophilic attack & 3' end
be removed too
> exons
-
may
SPLICEOSOME
snRNPs
/
3 00 other proteins
end
&
u, ps
>
-
Recog intron exon boundary Other
conserved regions each contains
ve end a bind first sing le short
RNA Molecule
VL
U 3 Recruited
then 13 4 are released
which activates the spliceosome
Binding tightly Regulated
is
>
spliceosome only recognises real introns
-
with
highly conserved motifs
S
5' GU
Essential 31 AG
↳ upstream pyrimidine sequence
Ccytosine 3 uracil
Branchpoint site >
-
Ademine for nucleophilic attack
SR proteins promote binding (Ser & Arg rich splicing fastors
Regulation - of U1 and U2 SMRNPs
Bind to enhancers Si 3
S
I
31
·
in sxons (ESE) -
or intron
sequences [ISE)
Stabilise
·
binding
·
encourage binding
cleared
cleared
*
-
hnRNPs bind to
splicing
suppressors in exons (ESS)
or introns (ISS) and inhibit
, Reverse transcriptase PCR 3 Northern Blotting
RcDNA Synth
isolate
1) MRNA
make use of
poly A tail
RT 3 poly T- > CDNA
2) standard PCR
add RNAse to degrade mRNA
left with SSCDNA
·
primers
Tag Pol .
·
SEX RETERMINATION IN INSECTS
Ratio of X: Y determined sex not active Y
Mechanism in drosophila
X = male
XX = female
no .
of X chromosomes determined by expression
level of 4 X linked genes 33
encode
TFS
S 3
scule All bind to
-
Sisterless promoter of Sex lethal Binary
mmt
gene
-
unpaired Sfourth) encodes a ligand that SX/
activates
maternally supplied TF
a
After 14th nuclear division formation of individual cells
4 scute , sisterless ,
mut b unpaired turned off forever after 14th
division
Sxl
In order to
getbindexpression of need cons of
proteins to to b
promoter activate
X will reach first because 2 copies :
2 protein conc .
-
proteins degraded after 14th
XY = fernale because in haploid
takes longer >
-
15th division
