DNA, RNA, and Protein
Synthesis
Ch 12 section 3
A. Learning Goals
1.
2.
3.
4.
Tell how DNA differs from RNA
Describe the role of the ribosome during
protein synthesis.
Compare and contrast Transcription and
translation
Break down the Genetic Code…from
DNA TACCGATCATGGATT
A. DNA: Deoxyribonucleic Acid
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Double strand of nucleotides, called
double helix.
Each nucleotide consist of 1.
deoxiribose sugar 2. phosphate
and 3. base
Basis are adenine, guanine,
thymine, cytosine.
DNA is a genetic library, the original
blueprints!!
Discovered by Watson and Crick
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DNA From The Beginning
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B. RNA- Ribonucleic acid
Single strand of nucleotides
 Each nucleotide consist of
1. Ribose sugar
2. A phosphate group 3.
Nitrogen base
 Uracil instead of thymine !!!!!
 U and A, C and G
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*RNA is a working copy of
DNA
C. Base Pairing: Chargoff ’s Rules
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In DNA…
Adenine always pairs with Thymine
Cytosine always pairs with Guanine
Question: If you have 5673 cytosines in a strand of
DNA, how many guanines will you have?
Answer: 5673
In RNA… Thymine is replaced by Uracil
DNA TACATTGACCGATT
RNA AUGUAACUGGCUAA
D. Central Dogma for Protein
Synthesis…The Big Idea!!!
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Protein synthesis… the making of proteins
by putting Amino Acids together!
transcription
Dna
Nucleus
translation
Rna
cytoplasm
protein
ribosome
E. Three types of RNA
1.
2.
3.
Messenger RNA, mRNA: carry message
with instructions for making proteins.Every
three bases makes a codon. Ex. AAG
Ribosomal RNA, rRNA: part of the
ribosome, proteins are assembled here.
Transfer RNA, tRNA; transfers amino acid
to the ribosome as it is read by mRNA.
Every three bases make one anticodon
Ex. UUC
F. Transcription: making a copy of
the original message (like taking notes)
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Start (
) and stop signals ( ) direct
beginning and end of note taking.
mRNA make a summary: it takes out the info
that does not code for proteins . Introns
are junk DNA!
It keeps the exons which will code for
proteins. Exons yes, introns no!
animations
G. TRANSLATION: making sense of
the genetic language
mRNA codons are transcribed in nucleus, exits to
cytoplasm to attach to ribosome.
 tRNA brings the anticodon with the right amino acid
to the ribosome. The Amino acid is added to the
polypeptide chain.
 Ex. DNA
AGCTTA
mRNA UCG-AAU ( each 3 are a codon)
tRNA
AGC-UUA (each 3 are an anticodon)
amino acid serine aspargine
protein
ser-asp
animations
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H. Proteins
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Can be from 2 to ____ amino acids long.
There are 20 types of amino acids
Your DNA codes for proteins. These
proteins contribute to how you look and how
you function.
Can very in the sequence (order) and in the
number of amino acids!!
Race the Cell