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DNA Review
• The structure of DNA is a double helix, which is
similar to a “twisted ladder.” It’s structure
consists of a 5 carbon sugar called
(deoxyribose), a phosphate group and one of
four nitrogen bases (Adenine, Thymine,
Cytosine or Guanine).
• The nitrogen bases hold the codes for proteins
which determine our genetic traits.
RNA
The structure of RNA is a single strand nucleic acid
involved in the making or proteins or Protein
Synthesis.
It’s structure is made up of
a 5 carbon sugar called
Ribose, a phosphate group
and one of four nitrogen
bases (Adenine, Cytosine,
Guanine and Uracil (takes
the place of Thymine and
pairs to Adenine)
There are 3 types of RNA:
mRNA – messenger RNA which is the
transcriber.
tRNA - transfer RNA which is the transfer
of amino acids and translator.
rRNA – ribosomal RNA which helps make
up part of the Ribosomes.
Important Vocabulary Terms
• DNA Triplet: a 3 base section of DNA that
carries the code for specific amino acids to make
a protein.
• Codon: a 3 base section mRNA that codes for a
specific amino acid (ex: AUG – start codon).
• Anticodon: a 3 base section of tRNA that
complementary to mRNA (ex: UAC) and carries
the amino acid.
Protein Synthesis
Process by which an
organism’s genetic code
(DNA) is translated into
protein.
Two steps of Protein Synthesis
Step 1: Transcription: Info from DNA copied to
a strand of mRNA
writes
Step 2: Translation:
Info from mRNA used to
form amino acid chains
(protein)
reads
Building RNA - Transcription
1. DNA must first unwind.
2. RNA Polymerase, an
enzyme, separates strands
of DNA exposing the
nitrogen base pairs.
3. RNA Polymerase then matches RNA
nucleotides with one side of the DNA template.
In RNA,
A
U
NO “T”
C
G
A bonds with T (on DNA strand), but U
bonds with A (on RNA strand)
4. The mRNA is then spliced because DNA
also carries information that does NOT code
for proteins.
The spliced portion is
called an Exon because
this is the region of
DNA that codes for
protein & will exit nucleus
The Intron is the
noncoding region of DNA
that does NOT code for
proteins and is spliced
out and remains in the
nucleus
5. The spliced
mRNA leaves
the nucleus &
attaches to
ribosomes in
the cytoplasm.
rRNA
Translation: the building of proteins by
using the information from mRNA.
1. mRNA strand attaches to the ribosome and
is used to translate into a protein.
2. tRNA molecules transfer amino acids to the
ribosomes.
3. As tRNA bases pair up with mRNA, it leaves
amino acids which are used to form the protein
chain.
REVIEW: What are 3 differences between
DNA and RNA?
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DNA is double stranded
RNA is single stranded
DNA has Thymine
RNA has Uracil
DNA has Deoxyribose sugar
RNA has Ribose sugar