Transcript DNA PROCESSES REVIEW

DNA PROCESSES
Replication, Transcription and
Translation
Replication
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Replication is the process
in which chromosomes
are copied.
When cell division occurs,
2 new cells with exactly
the same genetic
information as the original
cell is created.
DNA cannot divide into
two, but it can be copied!
Replication
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During replication, an enzyme
“unzips” the DNA molecule,
allowing free nucleotides to
join with their correct nitrogen
bases.
Remember!!! Adenine always
pairs with thymine, and
cytosine always pairs with
guanine.
When replication is complete,
we are left with 2 new
molecules of DNA, each
containing an original parent
strand and a new
complimentary strand.
Transcription
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Transcription is the process of transferring
information from a strand of DNA to a strand
of mRNA.
As we know, DNA can be found in the
nucleus of cells. In order for proteins
(building blocks of all living organisms) to be
made, genetic information must be moved
out of the nucleus to a ribosome. For this to
be done messenger RNA (mRNA) must be
used.
Steps in Transcription
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Like in replication, an enzyme will unzip the
DNA molecule and RNA nucleotides will join
with the correct DNA nucleotides (G-C, A-U)
to receive the genetic information.
Once the exchange of genetic information is
complete, RNA becomes mRNA. (Think
about it as if RNA now has a message to take
to the ribosome waiting in the cells
cytoplasm)!
mRNA, then leaves the nucleus and carries
the code to the ribosome.
Transcription
Translation
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Translation is the process in which information
carried in a segment or part of mRNA is translated
into a chain of amino acids, forming a protein.
IMPORTANT!
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Every 3 nitrogenous bases on the mRNA
strand is known as a codon. For example,
AUG is a codon.
Each codon, codes for a specific amino acid.
Steps in Translation
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Once the mRNA molecule is in the ribosome,
a transfer RNA (tRNA) molecule will bind to
the correct codon in mRNA.
Just as mRNA has a codon, tRNA has an
anti-codon which is also made up of 3
nitrogenous bases. The tRNA anti-codon will
join with the correct mRNA codon, thus
translating that segment of mRNA.
Translation
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As the tRNA anti-codons join with the correct codons
a chain of amino acids are formed, which then
makes a protein.
Amino acids
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During protein synthesis (the making of
proteins), a chain of amino acids have to be
formed to create the protein.
As mentioned earlier, codons code for amino
acids. So how do you know what codon
stands for which amino acid? Easy! You use
an amino acid table!
Amino Acids
How to find the amino acid…
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If you have the codon
AUG, the amino acid will
be found in the 3rd block
down (A Block), 1st column
(U Column) and last row
(G row) of that block.
AUG codes for
Methionine!!
Remember a chain of
amino acids make a
protein!
Diagram Overview
Practice Questions!!!!
April 2006 TAKS test
B.
Sickle-cell anemia is a disorder resulting from a
mutation that leads to the production of an
abnormal protein. Which component of the
DNA molecule provides instructions for the
production of a protein?
The phosphate groups
The sugar molecules
C.
Te sequence of nitrogen bases
D.
The bonds that hold the sugars to the bases
31.
A.
Answer
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The answer is C!!!
A codon is a sequence of 3 nitrogen bases,
and codes for a protein.
Question
Fall 2005
31.
A.
B.
C.
D.
CGGUAU
This is a short section of mRNA. Which
DNA code probably produced this section of
mRNA?
GCCTUT
GCCAUT
ATTGCC
GCCATA
Answer
The answer is D!!!
 mRNA CGGUAU
DNA GCCATA
Guanine ALWAYS pairs with Cytosine
In RNA Adenine pairs with Uracil.
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Question
July 2004
DNA passes information to RNA during the
process ofF. transcription
G. active transport
H. regeneration
J. osmosis
34.
Answer
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The answer is F!!!
Transcription is the process of transferring
information from a strand of DNA to a strand
of mRNA.
Question
July 2004
45.
A.
B.
C.
D.
Which molecule is most responsible for
determining an organism’s eye color, body
structure, and cellular enzyme production?
Complex Starch
Fatty acid
Carbohydrate
Deoxyribonucleic acid
Answer
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The answer is D!!!!
Deoxyribonucleic acid (DNA) is the blueprint
for how all living organisms are made.