Chapter 10
Section 4 Protein Synthesis
Flow of Genetic Information
• The flow of genetic information can be symbolized
as DNA
RNA
protein.
Section 4 Protein Synthesis
Chapter 10
RNA (Ribonucleic Acid) Structure and
Function
• RNA has the sugar ribose instead of deoxyribose
and uracil in place of thymine.
• RNA is single stranded and is shorter than DNA.

THIS PROCESS STARTS AT THE PROMOTER
REGION OF DNA. THIS REGION IS THE
STARTING POINT OF A GENE.

…IS THE COMING TOGETHER OF
TRANSCRIPTION FACTORS (PROTEINS) AND
RNA POLYMERASE AT THE PROMOTER.

…TAKES PLACE AS ENZYMES UNWIND THE
DOUBLE HELIX OF DNA AND mRNA
NUCLEOTIDES ARE MATCHED UP WITH THE
TEMPLATE STRAND OF DNA.

…HAS THE CODE FOR THE TYPE OF PROTEIN
TO BE BUILT ENCODED IN IT.

…TAKES PLACE WHEN A DNA TERMINATOR
SEQUENCE IS REACHED BY RNA
POLYMERASE.


A RNA CAP IS PUT ON THE 5′ END OF mRNA.
ON THE 3′ END OF THE mRNA A “POLY A
TAIL” IS ATTACHED.
THESE MODIFICATIONS AIDE IN PROTEIN
SYNTHESIS.


mRNA INTRONS ARE EXCISED BY snRNP’s
(RIBOZYMES & PROTEINS).
mRNA EXONS ARE SPLICED TOGETHER AND
WILL LEAVE THE NUCLEUS TO BE
TRANSLATED.

ALTERNATE SPLICING IS DONE TO MAKE
SLIGHTLY DIFFERENT VERSIONS OF PROTEINS
DURING TRANSLATION.

THE GENETIC CODE IS THE
CORRESPONDENCE BETWEEN THE CHEMICAL
LANGUAGES OF mRNA AND PROTEIN.
 TRANSLATION INITIATION IS THE
STAGE WHEN THE INITIATION
COMPLEX FORMS.
• THE INITIATION COMPLEX
CONSISTS OF mRNA, INITIATOR
tRNA, THE AMINO ACID
METHIONINE, AND A SMALL
RIBOSOMAL SUBUNIT.

ELONGATION BEGINS WHEN A LARGE
RIBOSOMAL SUBUNIT ATTACHES TO THE
INITIATION COMPLEX.

A POLYPEPTIDE (AMINO ACID CHAIN WHICH
IS A PROTEIN) STARTS TO FORM AS tRNA’s
CARRY THEIR CORRESPONDING AMINO
ACIDS TO THEIR COMPLEMENTARY mRNA’s.
tRNA’s ARE RECYCLED AFTER DROPPING OFF
THEIR AMINO ACIDS.

THE P site ON A RIBOSOME HOLDS THE
GROWING AMINO ACID CHAIN.

THE A site HOLDS THE NEXT AMINO ACID TO
BE ADDED TO THE AMINO ACID CHAIN.

THE RIBOSOME MOVES DOWN THE mRNA
ONE CODON AT A TIME AS TRANSLATION
PROGRESSES.

TRANSLATION ENDS WHEN A STOP CODON
IS REACHED.

A RELEASE FACTOR ATTACHES TO THE STOP
CODON AND CAUSES THE PROTEIN TO BE
RELEASED. THE TRANSLATION COMPLEX IS
BROKEN DOWN AND RECYCLED.
 THE PRIMARY (1◦) STRUCTURE OF
A PROTEIN IS ITS AMINO ACID
SEQUENCE.
 THE SECONDARY (2◦) STRUCTURE
OF A PROTEIN IS FORMED BY
HYDROGEN BONDS BETWEEN
NONADJACENT CARBOXYL
GROUPS AND AMINO GROUPS.

LOOPS, COILS, SHEETS, BARRELS, AND
HELICES ARE SOME OF THE SHAPES FORMED
AT THIS STAGE.

THE TERTIARY (3◦) STRUCTURE OF A
PROTEIN FORMS AS R GROUPS INTERACT
WITH WATER.

PROTEINS THAT CONSIST OF MORE THAN
ONE POLYPEPTIDE FORM A QUATERNARY
(4◦) STRUCTURE.

CHAPERONE PROTEINS HELP TO DIRECT
PROTEIN FOLDING.


UBIQUITIN IS AN ENZYME THAT HELPS
STRAIGHTEN OUT MISFOLDED PROTEINS.
A MISFOLDED PROTEIN WITH MORE THAN
ONE UBIQUITIN TAG ATTACHED TO IT WILL
BE RECYCLED IN AN ORGANELLE CALLED A
PROTEASOME.

THE FOLDED SHAPE OF A PROTEIN
DETERMINES ITS FUNCTION IN A CELL.

MISFOLDED PROTEINS CAUSE GENETIC
DISEASES.

PRIONS (MISFOLDED DISEASE CAUSING
PROTEINS) MAKE NORMAL PROTEINS FOLD
INTO DISEASE CAUSING ONES.

SCRAPIE & MAD COW DISEASE
(TRANSMISSABLE SPONGIFORM
ENCEPHALOPATHIES)