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Protein Synthesis Teacher Notes
I. Protein Synthesis
A. DNA Replication
1. Occurs in the nucleus prior to any cell division
2. Enzyme is used to “unzip” or “unwind” the DNA
3. Another enzyme is used to build a complementary
strand of DNA from the template piece of original DNA
a. Nitrogen bases pair up
1. A – T
2. C – G
4. As a result, you create two identical strands of DNA
B. Transcription
1. DNA strand unzips
a. The bonds between the nitrogen bases are
broken
b. Initiated by an enzyme that binds to a site on
DNA
2. A single strand of mRNA (messenger
RNA) is made
a. Pair up the nitrogen bases
1. A  U
2. T  A
3. C  G
4. G  C
3. mRNA then travels from nucleus to
cytoplasm
a. Why is mRNA called messenger
RNA?
1. Because it carries the
directions to make a protein
to the ribosome like a message
4. Types of RNA
a. mRNA- messenger
1. Brings message from nucleus to ribosomes in cytoplasm
b. rRNA- ribosomal
1. Make up a ribosome
c. tRNA- transfer
1. “transfers” amino acids from the cytoplasm to the ribosome
to be added to the chain
C. Translation
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1. mRNA meets up with a ribosome
a. Function of ribosome is to be site for protein
synthesis
2. tRNA molecules bring amino acids to ribosomes
3. An mRNA codon will pair with a tRNA anticodon
a. Codon: 3 Nitrogen base sequence in mRNA
that specifies a specific amino acid
b. Anticodon: 3 Nitrogen base sequence in tRNA
4. As tRNA’s are added, amino acids are bonded
together and will be released as a fully functional protein.
5. How do you know what amino acids make up a particular protein?
a. We use an mRNA codon chart
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