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DNA PROCESSES
Transcription using DNA
Vs.
Replication of DNA
TRANSCRIPTION
MAKING A BRAND NEW
RNA MOLECULE!
PURPOSE OF TRANSCRIPTION:
Why must RNA be formed?
 DNA
holds the code for the assembly of
amino acids (to build a protein).
 Proteins
must be synthesized at the
ribosome and DNA is unable to leave the
nucleus of eukaryotic cells.
 RNA
can be the messenger of the code
PROCESS OF TRANSCRIPTION
How is RNA formed?
 The
first step in
protein synthesis
1. DNA is partially
opened by HELICASE
inside the nucleus.
PROCESS OF TRANSCRIPTION
How is RNA formed?
2. RNA polymerase
(an enzyme)
synthesizes a new
mRNA strand by
putting RNA
nucleotides in the
order DNA instructs!
AU
GC
PROCESS OF TRANSCRIPTION
How is RNA formed?
3. Messenger RNA
can leave the
nucleus with
instructions to build
a protein. DNA
closes and is
virtually unaffected.
DNA REPLICATION
also known as synthesis of DNA
MAKING A BRAND NEW
COPY OF DNA!
PURPOSE OF REPLICATION
Why must DNA copy itself?
 DNA
must copy itself in order
to make new cells for the body
to grow or repair!
 Remember:
you have ALL
your DNA in ALL your cells. If
your cell needs to divide, you
must have the DNA in there!
Steps of REPLICATION, or
synthesis, of DNA
1.The DNA double helix is
unzipped completely by
HELICASE inside the
nucleus.
Steps of REPLICATION, or
synthesis, of DNA
2. DNA polymerase (an
enzyme) synthesizes two
new DNA strands by putting
DNA nucleotides onto the
ends of each template
strand.
AT
GC
Steps of REPLICATION, or
synthesis, of DNA
3. The nucleus is left with
TWO exact copies of ALL the
DNA.
The copies will wind back
into chromosomes. There
are now TWO copies of each
chromosome.
BEFORE
REPLICATION
AFTER
REPLICATION
Open the doors to your foldable:
 Describe
the PURPOSE and PROCESS
of TRANSCRIPTION on the left.
 Describe
the PURPOSE and PROCESS
of REPLICATION on the right.
You must know the differences
between these two DNA processes!
REPLICATION ANIMATIONS:


http://www.johnkyrk.com/DNAreplication.html
http://www.stolaf.edu/people/giannini/flashanimat/mol
genetics/dna-rna2.swf
MODEL DNA REPLICATION!
NOW, YOU PRACTICE!
Go back to the DNA template in your
notebooks, page 41.
 Open the strand of DNA (you are
helicase).
 PASTE in each individual nucleotide that
matches the bases you have already
glued in (you are DNA Polymerase)
 YOU HAVE JUST REPLICATED DNA!
Describe:
 Write
a description of what you just did in
order to replicate the DNA in your
notebooks. Use the following terms:
HELICASE
ORIGINAL DNA STRAND
DNA POLYMERASE
NEW DNA STRAND
TEMPLATE STRAND
NUCLEOTIDES
SYNTHESIS