10 Transcription i i

8/10/2019 10 Transcription i i

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C

A

G F

A

E (S)


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CC

DNA

A :

A/ ( )

C


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C C (CC)

A/H

DA


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H

H

I

DNA

L+

HA HDAC


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DA

HDNA

?

DA .

I DA,

,

, DA ,

,

.

DA

M


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CAIA

1 RNA

R RNA ( )

R

ECAIA

3RNA

N

R

N

E

G *

P :

M 5 3


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D RNA

*1

*1 5 A

(28, 18 5.8)

*

* RNA ( RNA)

E A ()


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A II

DEBEI


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A II

(

D


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OC PSE

RNA II

A III C III

III (RNA, 5S RNA)

III (RNA) II

A III


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G

F

FIIA

FIIB

FIID

FIIEFIIF

FIIH

C A II ,

FIID AA (B)

810 BP (AF)

B


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AA

I AA (BP),

A A II

C (CD) A II,

26 52


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F GF(G )

I RNA II; FIIB

S BP AF FIIA

R ; BP FIID (AF)

R AA I ;

FIIB

FIID (BP

)

GF F

H

;

C (

) RNA II

FIIH

I FIIH;

FIIH

FIIE

R RNA IIFIIF

GF ( )


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A II

( ). DNA ().

A , .

S ,

A , , .

I , AP .


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DA A II

.

E.

Multiple enhancers enable a gene to respond differently to differentcombinations of activators.

This arrangement gives cells, in a developing organism,exquisitely fine control over their genes in:- different tissuesor at-different times

: B


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C :

AA ( 5 AAA3 , A )

I ( 5 CARR3 , C , R A G)

B , :

CAA ( 5 GGCCAAC3 ), NF1 NF

GC ( 5 GGGCGG3 ) S1

( 5 AGCAAA3 ), O1 ( O )

A II

C

: AM CE( 5 CGCA3 ), CREB (HE) ( 5 CNGAANCAGA3 ), HSP70

C :

( 5 GAAR3 ) GAA1 ; ( 5 CAACGAC3 ), MD

M .

B ( 5 CCAACCC3 )

I


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C DA

( )

GE

EE

DE D3

E

AE


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C

:

DA

H

. ( DNA)

DMAI

MIF .

A G

P . GAL4 GAL4

NH2 40 50 94 COOH

DNABD D AD


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21/56


22/56

H DA

D


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24/56

E. 2 ()

C R


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E. 3 D

.

M


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100,000

(LCR).

C

.

E

.

E

B

E


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R :

C1

GAA1 ;

5 3

E. 4 M

S GAA1 ;

GAA1

I


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F EE

RNA

GF

CRC

. C

, DNA

. H

:

, . A

,


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I

CMEII

M

.

I ,


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A

C

S

P


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M RNA

RNA

.

P RNA


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C A 7 5 RNA

M RNA 5

F

I A

2

1

3

I

55

1 F

2 G (55 GMP)

3 G


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mRNA splicingabout introns

Introns are rare in bacterial genes. They have been observed in archae,

bacteriophages and some eubacteria

They are present in mithocondrial and chloroplast genes, as well as nuclear

genes

All classes of enes includin those that code for tRNA and rRNA ma contain

introns

In eukaryotic organisms number of introns seem to be related with increasing

organismal complexity

Introns tend to be longer than exons

Most introns do not code proteins*

The discovery of introns forced reevaluation of the definition of a gene


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I

Insulin 1.4 2 69

-globin 1.6 2 61

G L(K)

N

%

Serum albumin 1.8 13 79

Type VII collagen 3.1 117 72

Factor VIII 186 25 95

Dystrophin 2400 78 98

% A (%)


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Types of introns

O RNA, RNAG II

E RNA, RNA, RNAG I

E RNAAAC

E RNAGAG

I

N RNA

RNAA

E RNAPRNA

O RNAO RNAG III

- The splicing of all pre-mRNA introns takes place in the nucleus andis probably required for RNA to move to the cytoplasm

- The order of exons in DNA is usually maintained in the spliced RNA


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RNA

, , ,

B (G I II)

,

A

B


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A

E. GAG

C 5 ,

, 3

(1840 )


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A

C 5

C 3


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1 3CCACAA

2 3 AGAG

5 GAAG 3

6 3CGACGAGACA

5 3CACCG

4 3GGCGAAG

GGCACGACC


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G I G

A

G II

A

E


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E

Self-splicingintrons

Some introns of Groups I, II and III splice themselves by an autocatalytic process.There is also growing evidence that the splicing pathway of GU-AG introns includes atleast some steps that are catalyzed by snRNAs ( Newman, 2001)

Ribonuclease P The enzyme that creates the 5 ends of bacterial tRNAs consists of an RNA subunitand a rotein subunit with the catal tic activit residin in the RNA

D

Ribosomal RNA The peptidyl transferase activity required for peptide bond formation during proteinsynthesis is associated with the 23S rRNA of the large subunit of the ribosome

tRNAPhe Undergoes self-catalyzed cleavage in the presence of divalent lead ions

Virus genomes Replication of the RNA genomes of some viruses involves self-catalyzed cleavage ofchains of newly synthesized genomes linked head to tail. Examples are the plantviroids and virusoids and the animal hepatitis delta virus. These viruses form adiverse group with the self-cleaving activity specified by a variety of different base-paired structures, including a well-studied one that resembles a hammerhead.


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M A 3 (A)

P A RNAS;


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A

C

3 A

(A)

3 A

(A) (ABII)

(A)

ABII

(A)


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5

5

M

P

5

5

A /

FE ; NE ;

EE ; PE


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E A (A)

3 (. RNA)

( 7

)SLBP ( )

7 (RNP)

HDE ( )


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R 2


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A

A :

A M 3


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A


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A

:

,


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2 , :

1 2 3 1 3

: 1 2 3

1 2 3

A

3 5:1 2 3 1 2 + 3

E :

E


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A A (D C A M)

DCAM

I ,

38,016

RNA 24 , (A, B, C, D) .

E RNA :

1 12 A

1 48 B

1 33 C

1 2 D

E DSCAM

.

I ,

DSCAM .

S


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L

( L)

S

RNA

RNA

D D

( )

R RNA

,

D

D ,


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C 22%

3 .

C , RNA

PAS

A A


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PA

B

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10 Transcription i i