Transcript Ch 13 RNA and Protein Synthesis

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Review Describe the three main difference
between RNA and DNA
Explain List the three main types of RNA and
explain what they do
Infer Why is it important for a single genes to be
able to produce hundreds or thousands of RNA
molecules
CH 13 RNA AND PROTEIN SYNTHESIS
13.1 RNA
RNA
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Nucleic acid that consists of a long chain of
nucleotides
Copied from DNA.
Differences Between
RNA and DNA
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Sugar is ribose instead of deoxyribose
RNA is generally single-stranded and not doublestranded
RNA contains uracil (U) in place of thymine (T).
Comparing RNA and DNA
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Roles of DNA and RNA are similar to the master
plans and blueprints used by builders
Master plan has all the information needed to
construct a building.
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Never bring a valuable master plan to the building
site, where it might be damaged or lost
Instead they bring inexpensive copies or blueprints.
Functions of RNA
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Disposable copy of a segment of DNA
Protein synthesis.
3 Types of RNA
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Messenger or mRNA
Ribosomal or rRNA
Transfer or tRNA.
Messenger RNA
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Carry copies of DNA instructions.
Ribosomal RNA
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Make up ribosomes.
Transfer RNA
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Transfers each amino acid to the ribosome
according to mRNA.
Transcription
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Segments of DNA serve as templates to produce
complementary RNA molecules
Makes a copy
Occurs in nucleus of eukaryotes.
RNA polymerase
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Enzyme similar to DNA polymerase
Binds to DNA and separate strands
Uses one strand of DNA as a template and makes a
complementary RNA strand.
Promoters
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Regions of DNA that have
specific base sequences
Shows RNA polymerase
where to bind and start
Similar signal shows
where to stop.
RNA Editing
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Exon
 The
part of the DNA that codes for the protein that is
to be made
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Intron
 The
part of the DNA that does NOT code for the
protein that is to be made.
Why Have Introns
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Genes and Protein instructions may overlap in DNA
Instructions for one protein may cut out one set of
introns, but different introns may be cut out for a
different protein
Don’t have a complete answer
 Neapolitan
ice cream.

Chocolate
 Exon
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Vanilla
 Intron
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Strawberry
 Intron.