Transcripton

Making Proteins Requires
1. 
2. 
3.  

-More specifically, genes are segments of that encode information from our   -The information is for making  and   molecules that have biological
functions

mRNA editing does not occur in  

A gene is a  

Exons ->   They are usually
separated by an  

Intron -> the   because it is
 during  .

There are  types of introns

Some introns cut themselves out-> Group
 

Some introns need the spliceosome to get
cut out ->  
• spliceosome is made up of other
 

Some introns need enzymes to get cut out
->  

Group I and group II are considered  

The sequences at the beginning and end of the RNA are  into a protein.
Often called and    in the mRNA.

5’ end -> contains the  
• In mRNA-> contains the
  and
 

3’ end -> contains the  .
• In mRNA -> contains the  and  .

Transcription is gene  

 expression - genes being produced at all times
Examples include:  , 

  expression - allows for tighter controls of gene expression
Example includes:  

How is DNA freed from histones?
1. Histone  
2. Histone  

In histone  add acetyl and neutralizes  . Only occurs in areas that need to be transcribed.  remove after transcription.

Histone methylation
• Histones can be methylated on   and  residues only
• It weakens the chemical attractions between  and  

All genes (eukaryotic and prokaryotic) have a unique region of DNA sequence upstream of (before) the transcriptional start site that serves as a binding site for the  
- These regions are called  

Promoters Give
1.  
2.  (No  = no  )
3.  

Although each promoter is unique, most share a few common sequence elements that are evolutionarily conserved, called  

  recognize the promoter regions, but do not make direct contact with the promoter in eukaryotes.

What are the 3 major consequences sequences?
1)  located -25 to -30.
2) - Located -70 to -80. Always contains either   or  
3)   Usually has the sequence   and is typically found ~ -110 bps.

Mutations of the   box causes LOWER levels of transcription

RNA polymerase I – Produces  

RNA polymerase II – Produces  

RNA polymerase III –  

RNA polymerase  make ribosomal RNAs

Transcription: Initiation -> binding of   to the   -> 

2 classes of transcription factors
(1)   = common set needed to get transcription started
(2)  = provide transcriptional control

Binding of basal transcription factors to the promoter (and
recruitment of RNA pol II)
1) TBP =  
2) TFIIA =  
TFIIB =  
3) RNA polymerase II (escorted by ) then comes in and
interacts with the preassembled complex
4) TFIIH =  

The complex of proteins is assembled on the  ,   will leave most of the other proteins behind and start making  

RNA pol reads the DNA nucleotides and brings in complimentary RNA nucleotides
- Connects them via  
- Only transcribes  
- Synthesizes the  

RNA pol II = 
- Transcription continues well beyond the end of the gene
-However, there are characteristic termination sequences (rich in   and  )
-Like a  signal for the elongation processes
- Termination is coupled to  

In prokaryotes, RNA pol continues producing a complimentary RNA molecule until it transcribes a
 
- ANALOGY: Not like a  . More like spikes on the  

The terminator signals in prokaryotes have a DNA sequence contains an   (will form  ) followed by a
string of  .  straight  - cause the RNA to fall off the DNA template

3 Steps of RNA Processing
1. 
2. 
3.  

Addition of a cap is on the 

First Step In Capping
A   is added to the absolute   end
via a 5’-5’ linkage to the 
- Different from the normal   phosphodiester linkages

Capping of the mRNA Step 2
The guanine gets methylated to  . The first
few nucleotides also get methylated, but at the   position.

TEST QUESTION Capping of the mRNA
Cap-binding proteins then attach to the  
- Cap-binding proteins function to:
1) Protects the  from  in the cytoplasm
2) Indirectly allow   to attach to the small
ribosomal subunit for  

Addition of the poly-A tail happens at the  end

The string of adenines (poly A tail) function to:
1) Protects the  end of the mRNA from  
2) Allows cell to regulate  
- Longer the poly A tail, the  
3) Help in  

Introns are common in   but rare in  

- Most eukaryotic genes contain stretches of
noncoding sequence ( ) between coding
sequences ( )

Introns are in more  

Introns must be removed from  

Group I and II introns
- Found in   and a   (generally
small introns)
- Uses a molecule of   to excise itself out and “glue”
the remaining exons together

Nuclear pre-mRNA introns require  . Consensus sequences at the borders – attract the  . The spliceosome itself is made up of  .

Introns form   when removed and are  in cytosol

  of introns/exons can yield different proteins

In alternative splicing, all introns are  , Exons are  

Different mRNAs -> Different protein products (often called 

Most inhibitors of transcription are  that lack a 

What is an example of an inhibitor of transcription?

-  is a cyclic peptide of 8 amino acids. It is possibly the deadliest of all the amatoxins
• found in several species of the mushroom genus Amanita, one being the death cap (Amanita phalloides).
• Selective inhibitor of   and  (but not  )