Mcim L10 Gene Expression

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REPLICATION TRANSCRIPTION AND TRANSLATION
Eukaryotes
- -EUKAROTES HAVE REPLICATION AND TRANSCRIPTION IN THE NUCLEUS
- – TRANSLATIONIS IN THE CYTOPLASM
REPLICATION TRANSCRIPTION AND TRANSLATION
Prokaryotes
4 differences
- -PROKARYOTES HAVE COUPLED TRANSCRIPTION & TRANSLATION
- -TRANSCRIPTION & TRANSLATION OF A GENE AT THE SAME TIME AND IN THE SAME COMPARTMENT.
- -SIGMA FACTORS CONTROL INITIATION OF TRANSCRIPTIONP PROMOTER SEQUENCES OF PROKARYOTES ARE DIFFERENT FROM THOSE IN EUKARYOTES.
- -70 S RIBOSOMES OF PROKARYOTES ARE DIFFERENT.
- -SD SITES (RIBOSOMAL BINDING SITES) CONTROL INITIATION OF TRANSLATION IN PROKARYOTES, BUT NOT IN EUKARYOTES.
PROMOTERS

A PROMOTER IS A SEQUENCE OF BASES IN THE DNA WHICH ACTS AS A SIGNAL TO START TRANSCRIPTION OF RNA.
RNA POLYMERASE

AN ENZYME WHICH SYNTHESISES mRNA FROM A DNA TEMPLATE
FACTOR
- -ENABLES RNP TO BIND TO SPECIFIC PROMOTERS AND TO INITIATE TRANSCRIPTION
- -Not required for elongation
- -DIFFERENT FACTORS RECOGNISE DIFFERENT PROMOTER SEQUENCES
4 steps to transcription
- -RNP binds factor
- -RNP binds DNA (closed complex)
- -RNP maneuvers between DNA strands (open complex)
- -Elongation
At what point in the initiation of transcription is it no longer reversible

open complex
CONSENSUS SEQUENCES
def
example

A sequence in DNA that is constant when compared in multiple strands of DNA

-Promoters found at -35 and -10 positions
What is the -35 sequence?

TTG_ _ _
What is the -10 sequence?

TA_ _ _T
WEAK PROMOTERS
- -DO NOT MATCH THE CONSENSUS SEQUENCE AS WELL AS STRONG PROMOTERS
- -REGULATED BY ACTIVATOR PROTEINS
STRONG PROMOTERS
- -Match consensus sequence better than weak promoters
- -Turned off by repressors
PROMOTER MUTATIONS .

CHANGE THE DNA SEQUENCE IN THE CONSENSUS REGIONS
PROKARYOTIC RIBOSOMES
___s size
P TWO SUBUNITS(___S AND ___S)
___PROTEINS
_RNA’S
__S RNA BINDS mRNA FOR TRANSLATION
TARGET FOR ___
- 70
- 50 30
- 51
- 3
- 16
- ANTIBIOTICS
Initiation:
Shine Dalgarno Sequence

Site on mRNA just before start codon that 16S rRNA (in 30S subunit) binds to
Initiation:
Action of Ribosome subunits

50 S SUBUNIT BINDS TO 30S SUBUNIT FROM OTHER SIDE OF mRNA TO FORM 70S RIBOSOME
Why does 30S + 50S=70S?

50S subunit has groove that 30S fits into
INITIATION
What binds to AUG start codon?

N-FORMYLMETHIONINE-tRNA
TRANSLATION:
What Happens after start codon Is bonded?
- -SECOND AMINO ACYL-tRNA BINDS TO NEXT CODON AND RIBOSOMEFORMS PEPTIDE BOND
- -Elongation continues
- -At stop codon translation ends and ribosomal subunits are released

Author

Scottygo

240391

Card Set

Mcim L10 Gene Expression

Description

Mcim L10 Gene Expression

Updated

2013-10-13T21:50:12Z