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12–3 RNA and Protein Synthesis
12-3 RNA and Protein Synthesis
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12–3 RNA and Protein Synthesis
12–3 RNA and Protein
Synthesis
DNA is located in the nucleus.
DNA is impermeable to the nuclear envelope.
Genes are segments of DNA which code for the
production of proteins.
Ribosomes outside the nucleus make the
proteins.
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12–3 RNA and Protein Synthesis
Do you see a problem with this scenario?
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12–3 RNA and Protein Synthesis
RNA is the solution to this problem.
RNA is DNA’s main man.
RNA is DNA’s “go to guy”.
RNA is DNA’s number one
“get it done person”.
One of RNA’s jobs is to copy DNA’s
instructions and take those instructions
out of the nucleus to the ribosomes.
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12–3 RNA and Protein Synthesis
The Structure of RNA
The Structure of RNA
1. RNA is a type of nucleic acid which is made up of a
long chain of nucleotides.
2. Each nucleotide, like DNA, is made up of a:
1. 5-carbon sugar,
2. phosphate group
3. nitrogenous base.
(Sounds familiar..........just like DNA’s nucleotides)
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12–3 RNA and Protein Synthesis
The Structure of RNA
There are three main differences between RNA and
DNA:
• 1. The sugar in RNA is ribose instead of
deoxyribose.
• 2. RNA is a single-strand of nucleotides.
• 3. RNA contains uracil in place of thymine.
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Types of RNA
There are three types of RNA
•
1. messenger RNA ~ mRNA
•
2. ribosomal RNA ~ rRNA
•
3. transfer RNA ~ tRNA
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12–3 RNA and Protein Synthesis
Types of RNA
Messenger RNA (mRNA) copies DNA’s code for
making proteins and takes it’s copy to the ribosomes.
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12–3 RNA and Protein Synthesis
Types of RNA
Ribosome
Ribosomal RNA
Ribosomal RNA (rRNA) is the main component of a
ribosome. rRNA is bound into two “round” units by
proteins to form the large and small subunits which
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make up a ribosome.
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12–3 RNA and Protein Synthesis
Types of RNA
Amino acid
Transfer RNA
Transfer RNA (tRNA) transfers specific amino acids
to the ribosome for the making of the proteins.
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12–3 RNA and Protein Synthesis
Transcription
What is transcription?
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12–3 RNA and Protein Synthesis
Transcription
Transcription
RNA copies DNA’s code in its own language and
take the code to the ribosomes to make proteins.
Transcription requires the enzyme RNA
polymerase.
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Steps to Transcription:
1.During transcription, RNA polymerase
attaches to DNA and separates the DNA
strands.
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2. RNA polymerase then adds RNA
nucleotides to one side of the DNA
molecule/the sense side of DNA.
-DNA is a double strand of nucleotides
BUT only one side of the DNA molecule
actually codes for making proteins.
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12–3 RNA and Protein Synthesis
2 strands of DNA
1. Sense side:
Has code for making
proteins.
2. Antisense side:
Has no code~ makes
no sense.
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3. RNA nucleotides are added to the sense
side of DNA following the base pair rule:
Guinine bonds to Cytosine
and
Uracil bonds to Adenine
Sense side of DNA
A
T
G
G
C
U
A
C
C
G
T
A
C
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C
G
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12–3 RNA and Protein Synthesis
4. This single strand of RNA is now known
as messenger RNA or mRNA and it now
has a copy of DNA’s code for making
proteins.
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5. Since mRNA is single stranded it can now
take a copy of DNA’s code out of the nucleus to
the ribosomes.
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12–3 RNA and Protein Synthesis
Transcription
Hyperlink
RNA
RNA polymerase
DNA
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12–3 RNA and Protein Synthesis
The Genetic Code
Protein Synthesis:
The process of using mRNA’s copy
of DNA’s code to make all necessary
proteins.
Takes place where?
-at the ribosomes
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Proteins are made up of:
-long chains of amino acids
Total number of different amino acids that make
up all proteins:
-20
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These 20 different amino acids bond in various
orders (like the letters of the alphabet) to create
all proteins.
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12–3 RNA and Protein Synthesis
The Genetic Code
A codon consists of three RNA nucleotides in a row
on mRNA that code for a particular amino acid.
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Start codon:
Three nitrogen bases in a row on mRNA
that starts EVERY protein…..AUG
Amino acid
Methionine
starts every
protein
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Stop codon:
Three nitrogen bases in a row on mRNA
that ends every protein.
Three different codons: UAA, UAG, UGA
Stop codon
do not code
for any
amino acid
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12–3 RNA and Protein Synthesis
Translation
What is translation?
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Translation
Translation:
-Process by which the
ribosome reads mRNA’s code
and makes a protein.
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Translation
Steps of translation:
1. mRNA leaves the nucleus and take its code to
the ribosomes.
Nucleus
mRNA
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2. Ribosome attaches to mRNA and moves
along it looking for a start codon/AUG.
3. Transfer RNA/tRNA travels through the
cytoplasm locating the appropriate amino
acid.
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Anticodon:
anti =
opposite
An anticodon is three
nitrogen bases on the
end of tRNA .
Its code is opposite of
mRNA’s codon.
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12–3 RNA and Protein Synthesis
Translation
4. As the ribosome reads one codon at a time,
tRNA brings down the appropriate amino acid.
Phenylalanine
tRNA
Lysine
Methionine
Ribosome
mRNA
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Start codon
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12–3 RNA and Protein Synthesis
Translation
5. Amino acids bind together with peptide
bonds forming a long chain.
Lysine
tRNA
Translation direction
mRNA
Ribosome
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Translation
6. After a tRNA delivers its amino acid, it
breaks away and goes out to find a new
amino acid.
7. The process continues until the ribosome
reads a stop codon.
Polypeptide
Ribosome
tRNA
mRNA
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8. The long chain of amino acids
-now a polypeptide/protein
-breaks away and goes where?
-to the golgi
-Why to the golgi?
-to be processes and to be
given its 3-D shape
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Codon
Review:
The sequence of
bases in DNA is
used as a template
for mRNA.
Codon Codon
Single strand of DNA
Codon Codon Codon
The codons of
mRNA specify the
sequence of amino
acids in a protein.
mRNA
Alanine Arginine Leucine
Amino acids within
a polypeptide
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Hyperlink of translation
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Sense Strand of DNA:
CCAGTATACCCGAGTACCCCGCAGGAGCACCAGGAATTCCGCCATACACGCCCATCCCCACTCGAAAAAAAAAA
TATA Box
Poly-a-tail
Promoter Region
Termination Region
Site where transcription begins
Site where transcription ends.
Start of a gene
End of gene
Primary mRNA:
Intron
Exon
Intron
Exon
Intron
I------------------I------------------------------------------------I------------I-----------------------I-------------------------------------I
AUAUGGGCUCAUGGGGCGUCCUCGUGGUCCUUAAGGCGGUAUGUGCGGGUAGGGGUGAGCUUUUUUUUUU
Start codon
Tells ribosome to
start making protein
Stop codon
Start codon
Stop codon
Tells ribosome to
stop making protein
Mature mRNA:
Exon
Exon
I-----------------------------------------------I-----------------------I
AUGGGGCGUCCUCGUGGUCCUUAAAUGUGCGGGUAG
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DNA Codon
mRNA
codon
tRNA
anticodon
Amino Acid
AAA
UUU
AAA
PHENYL
GTC
GGA
GLYCINE
METH/START
GAT
GUG
VALINE
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CHNOPS LAB
DNA: TAC AGG GCG ATT
mRNA:____________________
tRNA:______________________
Amino Acid sequence: ____________________________________
Trait: _____________________
AMINO ACID SEQUENCE
TRAIT
Methionine-threonine-glycine-tyrosine-
Hairless
Methionine- threonine-glycine-glycine
Hairy
Methionine- threonine-proline-proline
Plump
Methionine- tyrosine-glycine-lysine
Skinny
Methionine-serine-arginine
Four-eyed
Methionine-serine-tyrosine
Two-eyed
Methionine-glycine-arginine-lysine-proline
Long nose
Methionine- proline-arginine-lysine-proline
Short nose
Methionine-phenylalanine-lysine
No freckles
Methionine- phenylalanine-asparagine
Freckles
Methionine- glycine-arginine-arginine
Blue skin
Methionine- glycine-arginine-phenylalanine
Orange skin
Methionine-isoleucine-isoleucine-leucine
Male
Methionine-isoleucine-isoleucine-glycine
Female
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Processing pre-mRMA into mature mRNA:
1. Cut out sections 1-3 of DNA and tape
together in order.
Section 1
C
G
G
C
T
A
A
T
Section 2
T
A
T
A
T
A
Section 3
A
A A
T
T T
G
C
C
G
A
T
A
T
A
T
T
A
A
T
C
G
G
C
A
T
A
T
T
A
T
A
A
T
A
T
A
T
T
A
A
T
T
A
C
G
A
T
T
A
G
C
A
T
C
G
C
G
T
A
A
T
A
T
T
A
C
G
A
T
T
A
C
G
G
C
A
T
A
T
T
A
A
T
G
C
A
T
T
A
T
A
C
G
C
G
A
T
C
G
T
A
G
C
G
C
G
C
T
A
A
T
A
T
T
A
T
A
T
A
G
C
T
A
T
A
C
G
A
T
G
C
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2. Locate the beginning of the gene on the
sense side of DNA (Top line) and
underline it.
How?
TATA Box
3. Locate the end of the gene on the
sense side of DNA and underline it.
How?
poly-A-tail
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4. Act like RNA polymerase…..
How?
Use your scissors to cut apart
the sense and antisense sides of DNA
beginning at the end of the TATA and
going to the beginning of the poly-A-tail.
Section 1
C
G
T
A
G
A
T
A
T
A
G
C
A
T
C
T
A
T
A
T
A
T
A
T
A
T
G
C
T
T
A
C
A
T
G
A
C
A
T
G
A
A
T
T
C
C
G
A
A
T
G
T
A
C
T
G
T
A
C
T
T
A
A
G
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5. Number the DNA nucleotides 1-54 (start at
end of TATA and to the beginning of the polya-tail.
6. Put in slashes, dividing it into 3’s or
codons.
Section 1
C
G
T
A
G
A
T
A
T
A
G
C
A
T
C
T
A
T
A
T
A
T
A
T
A
T
G
C
T
T
A
C
A
T
G
A
C
A
T
G
A
A
T
T
C
C
G
A
A
T
G
T
A
C
T
G
T
A
C
T
T
A
A
G
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7. Cut out the two sections of pre-RNA and tape
together. Put in slashes, dividing it into 3’s or
codons.
8. Complete the process of transcription.
How?
You now have just made pre-mRNA
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9. Locate the beginning of a protein.
How?
Start codon
AUG
10.Locate the end of a protein.
How?
Stop codon
UAA
UAG
UGA
11. Locate the next set of start and stop
codons.
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12.Label the introns and exons.
Introns:
Non coding
Exons:
Express……codes for a protein
13.Cut out the introns.
14.Tape together the exons.
15.Add a protective 5’ cap to the front and
a protective poly-A-tail tail to the end.
These protect the mature mRNA from
harmful enzymes in the cytoplasm.
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