transcription - ms. kropac€¦ · rna protein transcription translation tuesday, november 14, 17....

Transcription

Tuesday, November 14, 17

OverviewDNA

RNA

Protein


OverviewDNA

RNA

Protein

Transcription

Translation


Don’t Write This Down . . .

If the cell wants to make a specific protein it will take a ‘photocopy’ of the section of DNA that carries the information for specific protein

This photocopy is known a RNA


DNA RNA

deoxyribose, phosphate, nucleotide base

ribose, phosphate, nucteotide base

G, C, A, T G, C, A, U (Uracil)

double stranded single stranded

stable unstable

in the nucleus everywhere


Types of RNA

mRNA: Messenger RNA (transcription)tRNA: Transfer RNA (translation)rRNA: Ribosomal RNA (translation)


Stages of Transcription

1) Initiation2) Elongation3) Termination


Initiation

OverviewRNA polymerase binds to a promoter region


Initiation

A promoter is a DNA sequence that is high in adenine and thymine (TATA box)It is adjacent to the gene to be transcribed


Initiation

A promoter acts as a recognition/binding site for the TATA binding protein.

This protein is recognized by RNA polymerase II which docks to DNA


Initiation

RNA polymerase unwinds the DNA and the template strand is exposed.

Only on strand of the DNA is transcribedThe promoter is NOT transcribed


Elongation

RNA polymerase binds with the promoter and builds in a 5’ → 3’ direction


Elongation

No Okasaki fragments are created because only one strand is transcribed (no lagging strand)


Elongation

RNA polymerase works faster than DNA polymerase because there is no proof reading.


Elongation

Uracil complements adenine


Termination

A stop codon signals RNA polymerase to end transcription

UAA, UAG, UGA


Termination

mRNA and RNA polymerase are releasedDNA that was being transcribed rewinds into double-helical form


transcription - ms. kropac€¦ · rna protein transcription translation tuesday, november 14, 17....

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