DNA:
Replication, Transcription, and
Translation
DNA:
Structure & Function Review
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DNA stands for
DeoxyriboNucleic Acid.
It is the type of nucleic
acid that almost all living
things use to carry their
genetic traits.
DNA is carried inside our
cells as chromosomes.
Humans have 46
chromosomes, 23 from
each parent.
DNA:
Structure & Function Review
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DNA is a double helix made
of a sugar backbone and 4
bases.
The four bases are adenine,
thymine, cytosine, and
guanine.
The bases only pair with one
other specific base – this is
called base pairing rules.
Adenine pairs with thymine
(A-T)
Cytosine pairs with guanine
(C-G)
DNA:
Replication
• Each of our cells divide to create
new cells and repair old cells.
This is called mitosis.
• Before our cells can divide, they
have to copy their DNA. This
ensures that the new cells will
have an identical copy of DNA.
• When DNA is copied, we call it
replication.
DNA:
Replication
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During replication, DNA
“unzips” by separating the
base pairs on either side of
its backbone.
Then, using special
enzymes, a new base pair is
created that matches the
original.
When you are finished, you
have two identical DNA
molecules - one for the new
cell and one for the old cell.
DNA:
Making Proteins
• DNA is used by our
bodies to make
proteins. There are
two steps in
making proteins:
• 1) DNA
Transcription
• 2) DNA Translation
DNA:
Transcription
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Transcription is the process
of copying a segment of a
DNA molecule to produce a
matching strand of RNA.
RNA stands of RiboNucleic
Acid. It is also a nucleic
acid, just like DNA.
Unlike DNA, RNA only has
one strand of nucleotides
(DNA has two, remember
double helix).
DNA:
Transcription
• Another big difference
is that RNA has the
nitrogenous base uracil
rather than thymine.
• So in RNA, Adenine
pairs with uracil (A-U).
Cytosine still pairs with
guanine (C-G)…no
change there!
DNA:
Transcription
• In Transcription, DNA “unzips” just like in
replication.
• While it is unzipped, an enzyme makes a strand of
RNA by matching up the base pairs with one side
of the unzipped DNA.
• After the RNA is created, the DNA re-zips and
looks identical to how it looked prior to
transcription.
DNA:
Translation
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During the final step,
translation, the newly
created RNA travels
to a ribosome to be
“translated.”
This is where the
RNA’s base pairs
(adenine, uracil,
cytosine, and
guanine) are “read” in
threes.
Each set of three
letters codes for a
different amino acid.
DNA:
Translation
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An enzyme goes down
the line and reads each
set of three base pairs,
just like a scanner at
the store.
As it reads, the amino
acids are created.
Then, the amino acids
link together to form a
protein.
The type of protein
created depends on the
nitrogenous bases that
are read.