1. Transcription
Packet #21
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2. Introduction
The process by which information encoded in DNA specifies the sequences of amino acids in proteins involves two steps
Transcription
RNA molecule, complementary to the DNA template strand, is synthesized
Only one strand of DNA is used during transcription
Translation
More to come later
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3. RNA RNA molecules are single-stranded Ribonucleic Acid
Composed of RNA nucleotides
Phosphate
Sugar
Ribose
Nitrogenous Bases
Purines
Adenine
Guanine
Pyrimidines
Cytosine
Uracil
RNA molecules are single-stranded
DNA molecules are double-stranded
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4. Types of RNA Messenger RNA
Contains information that specifies the amino acid sequence of polypeptide chains
Serves as the template for protein synthesis
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5. Types of RNA Small nuclear RNA Transfer RNA Ribosomal RNA
Class of RNA molecules that transport amino acids to ribosomes for incorporation into a polypeptide undergoing synthesis.
“Transporter”
Ribosomal RNA
RNA that make up ribosomes.
Small nuclear RNA
RNA found in the enzyme spliceosome
More to come later
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6. Genes The Review Where are genes located?
On the DNA strand that makes up the chromosome
What is the name of the location on the chromosome where genes are located?
The Locus
What are genes composed of?
DNA nucleotides

7. Regions of the Gene I Regulatory Region The Coding Region
This is where RNA Polymerase, the only enzyme used during transcription, binds on the DNA strand
The Regulatory Region has a region known as the Promoter Region
The TATA Box is found in the Promoter Region
Location where RNA Polymerase binds and unzips the DNA molecule
The Coding Region
Area where RNA nucleotides are joined together to make an RNA strand.
The end of the coding region is called the terminator.

8. RNA Polymerase Only enzyme used during transcription.
However, there are three variations of the enzyme— depending on the type of RNA being produced
RNA Polymerase I
Transcribes rRNA genes
RNA Polymerase II
Transcribes protein coding (mRNA) genes
RNA Polymerase III
Transcribes other functional RNA genes
tRNA
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9. Transcription Step by Step
Location
Nucleus
RNA Polymerase binds at the promoter region (sequence) and unzips the DNA strand
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10. Transcription Step by Step
RNA Polymerase works downstream and reaches the coding region.
When in the coding region, RNA polymerase adds RNA nucleotides to the 3’ end of the newly formed RNA strand
New RNA strand ONLY grows in the 5’ to 3’ direction
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11. Transcription Step by Step
RNA Polymerase hits the “Terminator” sequence that signals the end of transcription
Newly made RNA is released
The New RNA strand is called pre-mRNA
Why? Because the pre- mRNA needs to be “groomed” for the BIG moment--Translation
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12. Sections of pre-mRNA Contains introns and exons. Introns Exons
The “Junk in the Trunk”
Regions of the RNA strand that must be removed, via splicing, and will not be used during translation
Exons
Regions of RNA that WILL be used and translated into amino acids during TRANSLATION
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13. Splicing Eukaryotic Cells
Removal of introns
Location
Nucleus of the Cell
Enzyme used is Spliceosome
Removes the introns via “cut & paste”
After splicing, the pre- mRNA will be officially known as mRNA
mRNA leaves the nucleus, through the nuclear pores, and enters the cytoplasm
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14. mRNA Transcription & Translation
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