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RNA and PROTEIN SYNTHESIS
© Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
DNA holds the information (code) to
make all of the proteins in a cell……..
But how is the information stored in DNA?
In the sequence of the nucleotides
Protein Synthesis
• How many nucleotides are
there?
4
• How many amino acids
are there?
20
HOW CAN JUST 4 BASES GIVE DIRECTIONS TO
MAKE 20 AMINO ACIDS?
Message is read in groups of 3 bases = CODON
_________
Codons represent different amino acids
UCGCACGGU
UCG-CAC-GGU
Serine - Histidine- Glycine
But how does the information in the
DNA get from the nucleus to the
ribosomes where proteins are made?
RNA
Ribonucleic Acid
MASTER PLAN
DNA stays safe in nucleus
TRANSCRIPTION (DNA→ RNA)
takes place in nucleus
TRANSLATION (RNA→ proteins)
takes place on ribosomes
in cytoplasm
“Blueprints” of master plan
are carried to building site
RNA
• Uses information from DNA
to make proteins
• Is a polymer similar to DNA
RNA- the Other Nucleic Acid
NUCLEOTIDES
Also made of ___________
RIBOSE instead
Sugar is _______
of deoxyribose.
SINGLE stranded
RNA is _________
URACIL instead
Contains _________
of thymine.
http://images2.clinicaltools.com/images/gene/dna_versus_rna_reversed.jpg
RNA Bases
3 Types of RNA
1. Messenger RNA (mRNA)
– Carries genetic message
from DNA to ribosomes
– Protects DNA
– More copies at the
same time
– Easier to move
3 Types of RNA
2. Transfer RNA (tRNA)
– carries the amino acids to
the ribosome
3. Ribosomal RNA (rRNA)
– Makes the ribosomes along
with proteins
3 KINDS OF RNA HELP WITH INFO TRANSFER
FOR PROTEIN SYNTHESIS
RIBOSOMAL
_________________RNA
(rRNA)
Combines with proteins to form ribosomes
TRANSFER
_________________RNA
(tRNA)
Matches m-RNA codon to add correct
amino acids during protein synthesis
MESSENGER
_________________RNA
(mRNA)
carries code from DNA to ribosomes
rRNA and t-RNA images from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
mRNA image from http://wps.prenhall.com/wps/media/tmp/labeling/1140654_dyn.gif
Transcription
• Process of making RNA from
DNA
• 3 Steps
–DNA unwinds
–Nucleotides are added (U instead
of T)
–mRNA leave the nucleus
What is the RNA Strand?
DNA CTA-GAG-CAA-GTC-ACT
What is the RNA Strand?
DNA CTA-GAG-CAA-GTC-ACT
mRNA GAU-CUC-GUU-CAG-UGA
What is the RNA Strand?
DNA TGC-AGT-AGG-TAC-ACT
What is the RNA Strand?
DNA TGC-AGT-AGG-TAC-ACT
mRNA ACG-UCA-UCC-AUG-UGA
Codons
Combinations of
nucleotides
needed to code
for all the
amino acids
64 codons
produce 20 AA
Section 12-3
64 possible codons
Some amino acids
have more than one
codon.
AUG
START= _______
STOP
3 codons for _____
Translation
Process of making proteins from RNA
• mRNA goes to the ribosome
• Ribosome reads mRNA in 3 base
triplets called codons
• Codon specifies
what amino acid
the tRNA brings
mRNA to Proteins
ANTICODON
___________
on tRNA
matches up with
CODON
________
on mRNA
EACH tRNA carries only one kind
amino acid
of _____________
Images modified from © Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved
REPLICATION
DNA → DNA ____________
TRANSCRIPTION
DNA → RNA ____________
TRANSLATION
RNA→ Protein ___________
can be
also called
which functions to
from
also called
to
which functions to
to make up
also called
which functions to
RNA
can be
Messenger RNA
Ribosomal RNA
also called
which functions to
also called
mRNA
Carry instructions
rRNA
Transfer RNA
which combines with
proteins
from
to
to make up
DNA
Ribosome
Ribosomes
also called
which brings
tRNA
amino acids to
ribosome
Make a Protein!
Codons
• AUG = start codon (methionine)
• UAA, UAG, UGA = stop
• Has to be read
in the correct
direction and
started in the
correct place