SUMMARY
Where?
When?
Why?
REPLICATION: DNA to DNA
Nucleus
S-phase of interphase
To make an exact copy of the DNA
(chromosomes) in preparation for cell division.
Transcription: DNA to RNA
Nucleus at the nucleolus.
Translation: mRNA to Protein
cytoplasm
G1, G2. Whenever a protein is required.
Mechanism used to control the cell by determining which
proteins, including enzymes, are made or not made.
Several sites along DNA called origins. Many
replication bubbles and forks speed up replic.
Promoter: TATA box, RNA polymerase uses the
repeating A/T pairs to recognize where a gene begins.
DNA polymerase reads the strands from the 3’
to the 5’ ends but builds 5’ to 3’ because the
resulting molecule must be antiparallel. New,
complimentary bases are added to both
strands. Leading/Lagging strands: Leading is
made continuously while the lagging strand is
made in fragments.
Replication bubbles merge and two identical
molecules result, called identical sister
chromatids.
RNA polymerase attaches to the promoter and begins
adding complementary RNA nucleotides.
Helicase, DNA polymerase, (primase, ligase,
many more.)
Helicase, RNA polymerase, many more.
How?
Start
Elongation
stop
Enzymes
involved
Diagrams
A termination sequence (also a TATA box) signals
where the gene ends and the RNA polymerase
detaches.
Fig. 10.5A p. 189
Fig. 10.9A
AUG is the mRNA start codon. It codes for Met.
Ribosome subunits lock on at AUG, add Met and the
next A.A. A peptide bond is made between the A.A.’s.
mRNA moves through the ribosome translocating the Asite A.A. into the P-site. The met tRNA, empty now, is
ejected from the ribosome; it searches the cytoplasm for
another Met and bonds to it. The next codon (#3) is now
in the A site and the tRNA with an anticodon
complementary to the codon is locked in. Another
peptide bond is made and the process is repeated.
A stop codon is reached. A termination factor binds the
A-site but carries no A.A. When the ribosome attempts
to attach the growing polypeptide chain, there is nothing
to attach to and the chain is set free.
The ribosome is enzymatic (ribozyme). No others to be
known by name. There is an enzyme that couples the
tRNA to its A.A.
Fig.
10.14
Fig. 10.10
Mrs. Loyd 
cschmittloyd@waukeeschools.org
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