Transcript RNA Structure

Protein Synthesis
How DNA uses RNA and Ribosomes to
make proteins.
RNA Characteristics
I. Bases
a. Adenine
b. Cytosine
c. Guanine
d. Uracil
e. Sugar – a ribose rather than a
deoxyribose
f. Phosphate
II. Structure
 A nucleic acid backbone
 single stranded.
III. Types of RNA
Three types of RNA are
used to make
proteins
 mRNA – messenger
RNA

rRNA – ribosomal
RNA

tRNA – transfer RNA
IV. mRNA Function
TRANSCRIPTON
A. transcribe DNA code
B. take code outside of nucleus to ribosome
C. give instructions to ribosome on how to build
protein
V. tRNA Function

To deliver amino
acids to the
ribosome as it is
building
(synthesizing)
protein
VI. rRNA Function
 are
where translation of RNA to
protein takes place
 Ribosomes are made up of protein
and ribosomal RNA (rRNA)
VII. Genes


Where do we find genes? (short arm
and long arm of chromosome)
Stretch of DNA
Genes face either direction on a strand
p
q
VIII. The CODE!!
A. James Watson and Francis Crick, with
the help of Rosalind Franklin’s X-ray
crystallography images unraveled the
structure of DNA:
B. The fact that bases paired led directly
to a theory of how DNA codes for
proteins. It took a few years to
determine that the bases spell threeletter “words” called codons
mRNA Codons
3
letters on mRNA are called codons.
These three letter codes are used to
determine which Amino Acid is to be
placed on the protein.
Ex: TAC
AUG = Start Codon
This is where you begin translation of
DNA’s code given to mRNA
mRNA Syntehsis (Transcription)
– A mRNA is transcribed (built) using the
DNA as a template.
– The anti-sense strand is used as the
template.

The resulting mRNA looks exactly
like the template strand of the DNA,
with one important distinction each
T is replace with a U.
See the mRNA codon chart (Pink)

Write the codon for Proline here:

Glycine?

Which amino acid has the most codons?

Which amino acid has the fewest?

Start codon starts each protein

Three codons tell a ribosome to stop
making a protein. List them here:
Protein Syntehsis
Translation
– mRNA is TRANSCRIBED or produced
from DNA in the nucleus.
– mRNA is shipped from nucleus to the
cytoplasm.
– A ribosome hooks to the mRNA and
“reads” to the first start codon. AUG
Anticodon – 3 letters found to match the
mRNA’s codon.
–A tRNA delivers a Methionine (start
codon), the first amino acid of each
protein.
–Many more tRNA’s deliver one of
the twenty amino acids to match
the codon of the mRNA to the
anticodon of the tRNA.
–The protein is synthesized (built)
one codon at a time reading from 5’
to 3’ along the mRNA.
 The protein only stops being built when a
stop codon is read.
video
 http://www.dnai.org/text/mediashow
case/index2.html?id=586
A Gene = ?


Copy strand – strand being read
Original Strand – strand not being read
A. Start Codon – AUG
B. Stop Codon -

5’TerminationSTOPPoly A
SequenceAUGPromoterOpen Reading
Frame3’
C. Termination Sequence -