1. Outline 12-3A RNA Ribonucleic Acid
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RNA
Ribonucleic Acid

2. I. Function A. To synthesize proteins II. Structure
A. A polymer of RNA nucleotides
B. Has 3 differences from DNA:
1. RNA consists of a single strand
2. 5-carbon sugar is ribose instead of deoxyribose
3. Has nitrogen base uracil instead of thymine
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3. b. Transmits information from DNA for use in protein synthesis
C. RNA exists in three different forms, each playing a different role in protein synthesis
1. Messenger RNA (mRNA)
a. Uncoiled strand
b. Transmits information from DNA for use in protein synthesis
c. Serves as a template (model) for the assembly of amino acids into polypeptides
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5. a. Single strand that folds back onto itself
2. Transfer RNA (tRNA)
a. Single strand that folds
back onto itself
CGU
b. Exists in 20 or more forms.
c. Each one bonds to one particular amino acid and transports it to a ribosome
d. Each has an anticodon on end
 This is a 3-letter sequence of nucleotides
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6. Anticodon

7. 3. Ribosomal RNA (rRNA)
a. This makes up part of the structure of ribosomes
b. Forms into two separate pieces that will form a place for the mRNA & tRNA to come to during the process of protein synthesis
Place for mRNA
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8. III. Transcription
A. A gene’s instructions for making a protein are encoded in the sequence of nucleotides in the DNA
B. These instructions are transferred from DNA to RNA in a process called transcription
1. The entire process by which proteins are made from DNA is called gene expression
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9. C. Steps of Transcription:
1. Enzyme, RNA polymerase, binds to the gene’s promoter on 1 strand
a. The promoter is a specific sequence of DNA that acts as a “start” signal
2. RNA polymerase unwinds & separates the strands of DNA
3. It adds complementary RNA nucleotides as it moves along
a. Replacing thymine with uracil
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10. Process of Transcription

11. 4. Continues until RNA polymerase reaches a “stop” signal
a. RNA molecule detaches from the DNA
b. DNA is zipped back up
c. RNA can then move out of the nucleus to the cytoplasm
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12. Process of Transcription