1.
2.
3.
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


Nucleic acid that consists of a long chain of
nucleotides
Copied from DNA.
Differences Between
RNA and DNA
1.
2.
3.
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


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.


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


Disposable copy of a segment of DNA
Protein synthesis.
3 Types of RNA



Messenger or mRNA
Ribosomal or rRNA
Transfer or tRNA.
Messenger RNA

Carry copies of DNA instructions.
Ribosomal RNA

Make up ribosomes.
Transfer RNA

Transfers each amino acid to the ribosome
according to mRNA.
Transcription



Segments of DNA serve as templates to produce
complementary RNA molecules
Makes a copy
Occurs in nucleus of eukaryotes.
RNA polymerase



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



Regions of DNA that have
specific base sequences
Shows RNA polymerase
where to bind and start
Similar signal shows
where to stop.
RNA Editing

Exon
 The
part of the DNA that codes for the protein that is
to be made

Intron
 The
part of the DNA that does NOT code for the
protein that is to be made.
Why Have Introns



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

Vanilla
 Intron

Strawberry
 Intron.