1. Overview
Transcription Detail
Another Transcription Animation

2. Part I: TRANSCRIPTION-
the building of mRNA, tRNA, and rRNA (takes place in the NUCLEUS)
Initiation:
RNA polymerase binds to the gene’s promoter on the template strand of DNA(a specific sequence of the DNA that acts as a “start signal” for transcription)
RNA polymerase unwinds and separates the two strands of the DNA.
Elongation:
RNA polymerase adds and then links complementary RNA nucleotides as it “reads” the gene” on the template strand.
Termination:
A “stop” signal on the DNA tells the RNA polymerase to detach from the DNA and release the RNA molecule

3. ATT CGC ACC TAA mRNA UAA GCG UGG AUU
DNA coding strand nucleotides (usually ~5,000 nucleotides):
ATT CGC ACC TAA
mRNA
UAA GCG UGG AUU

4. RNA Processing Before leaving the nucleus……..
A cap (methyl-guanine or mG) is added by enzymes to the starting end of the mRNA molecule
A poly-A tail is added to the end of the mRNA
The molecule is spliced. Introns are removed (non-coding nucleotides) and exons remain.

6. Translation
The assembly of a protein (occurs on the ribosome in the cytoplasm)
Translation Detail
mRNA leaves the nucleus through the nuclear pore and forms a functional ribosome with two ribosomal subunits, and a tRNA
Initiation: The mRNA “start” codon AUG is oriented in a region of the ribosome called the P site where the tRNA molecule carrying methionine can bind to the start codon.

7. Translation- cont.
3. The codon in the area of the ribosome called the A site is ready to receive the next tRNA.
Elongation: Both the A site and the P site are holding tRNA molecules- each carrying a specific amino acid. A peptide bond forms between the adjacent amino acids
The tRNA in the P site detaches and leaves its amino acid behind
The tRNA in the A site moves to the P site. The tRNA carrying the amino acid specified by the codon in the A site arrives.
Termination: Steps 4-6 are repeated until a stop codon is reached.

8. Translation animation
One more Translation animation

9. The mRNA strand would be: AUG UUU CAU UGA
If a segment of DNA is:
TAC AAA GTA ACT
The mRNA strand would be:
AUG UUU CAU UGA
This would code for the following amino acids:
Met Phe His Stop

10. Types of Mutations Point Mutations-
a change of one or just a few nucleotides in a gene
Substitution-
one nucleotide is replaced by another.
sometimes called a “missense” mutation
Insertion –
an extra nucleotide is added.
Deletion-
a nucleotide is omitted.

11. Frame shift mutations are caused by deletions and insertions
Original Strand 
AUG AAU GCG GAC UAA
Start Asparagine - alanine –aspartate –stop 
Ex. Deletion
AUG -AU GCG GAC UAA
becomes AUG AUG CGG ACU AA
Start -methionine -arginine- threonine-

12. becomes AUG AAU GCG GGA CUA A
Ex. Insertion
AUG AAU GCG GGAC UAA
becomes AUG AAU GCG GGA CUA A
Start- Asparagine- alanine - glycine- Leucine -