Download RNA Protein Synthesis

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Protein Synthesis
What is protein synthesis?
Is protein synthesis important?
What is RNA?
Where is RNA found?
Is RNA similar to DNA?
What is translation?
What is Protein Synthesis?
*Protein synthesis is the building
of proteins following the
instructions of DNA.
*The instructions of DNA are
written by the order of the
bases.
Example of instructions on DNA:
A-G-A-T-C-T-A-G
Why is protein synthesis important?
*Proteins make up the structure of an organism AND control all of the
organism’s chemical reactions to keep it alive.
Examples of proteins:
Walls of arteries, ligaments, hair, nails, muscles , bones and antibodies.
Protein Structure
A protein is made up of a chain of
AMINO ACIDS in a particular order,
held together by PEPTIDE BONDS.
Example of Protein:
*a chain of Amino Acids
Alanine
Phenylalanine
Glutamine
Valine
Proline
Lysine
NAMES OF AMINO ACIDS
Actual Sequence and names
of AMINO ACIDS
In Blood (Hemoglobin)
Shapes of Proteins
*the shape of a protein depends on its function & its order of amino acids.
Where does
protein synthesis occur?
*The DNA never leaves the nucleus.
*RNA copies the DNA in the nucleus.
DNA in the nucleus is safe !!
*RNA carries the instructions from
DNA out to the ribosome.
*The protein is built on the ribosome
in the cytoplasm.
DNA in the cytoplasm
can be destroyed
What is RNA?
RNA (ribonucleic acid)
*It is the nucleic acid responsible for
three things in protein synthesis:
1 – copying instructions from DNA
2 – carrying the instructions for
making proteins to the ribosome,
3 – putting the protein together on
the ribosome.
What makes up RNA?
Bases in RNA
Sugar in RNA
Ribose
Strands in RNA
“ONE”
3 Types of RNA
1. Messenger RNA (mRNA)
2. Transfer RNA (tRNA)
3. Ribosomal RNA (rRNA)
mRNA
tRNA
rRNA
Messenger RNA
(mRNA)
Function:
1. Goes into the nucleus and makes a copy of DNA using
RNA bases.
2. Takes the copy to the ribosomes.
3. Contains the “CODON” (group of 3 bases on mRNA)
Transfer RNA (tRNA)
Function:
- carries amino acids to mRNA at the ribosome to (make) the protein.
- contains “ANTICODON” (3 bases that match up w/codon on mRNA)
Ribosomal RNA
(rRNA)
*ribosomal RNA
major structural part
of the ribosome where
protein synthesis occurs.
Comparison of
DNA and RNA
Strands:
*DNA*
* RNA*
2
1
Sugar: deoxyribose
A, G, C, T
Bases: *Thymine
(A – T)
ribose
A, G, C, U
*Uracil
(A – U)
Steps in Protein Synthesis
Part I – Transcription
Part II – Translation:
Step 1: Transcription
Location: in the nucleus
Purpose: to copy the DNA code (order of bases) onto mRNA.
Events:
1.) DNA is unwound and DNA helicase unzips DNA strand.
2.) RNA polymerase reads the complementary base and adds the new
nucleotides along the DNA strand.
3.) mRNA is made, leaves the nucleus to go to ribosome.
Step 1: Transcripton
Location:
in the nucleus
Main Event:
mRNA comes into the
nucleus and makes a
copy of the order of the
bases on DNA.
RNA polymerase
Function:
Enzyme that recognizes
the complementary base
of RNA to DNA, and glues
them together.
Examples:
Guanine with Cytosine
Adenine with Thymine
*Uracil with Adenine
Step 2: Translation
Location: in the cytoplasm, on the ribosome.
Purpose: to convert the instructions of RNA (order of bases) into
amino acids, to make proteins.
Step 2: Translation
Events of translation:
1.) The first three bases of mRNA (codon) join the ribosome.
Usually (AUG – considered the start codon).
2.) tRNA brings the “amino acid” down to the ribosome. The three
bases on tRNA (anticodon) match the complementary bases on
mRNA.
Step 2: Translation … (final stage)
Events of translation:
3.) Each tRNA has an AMINO
ACID, that is determined by
its anticodon.
Ex: codon (AUG)
Amino Acid - methionine
4.) The amino acids are
joined by polypeptide bonds.
5.) The resulting chain of
amino acids are called a
PROTEIN.
Codons & Anticodons
Codon –
def: three nucleotides of mRNA.
Start codon - AUG
codons signals the start of a polypeptide chain
STOP codons - UAA, UAG, UGA - all three of
these codons signal the end of a polypeptide chain
Codons Amino Acids
*C U A - *G G C - *A A C - *U U A
Leucine - Glycine - Asparagine - Leucine
ANTICODON - segment of three bases on tRNA
that are complementary to the mRNA codon.
TRANSLATION
& tRNA
in pictures
Closeup of translation…
(mRNA, codons)
tRNA, amino acids, peptide bonds
Protein Synthesis, summary…
Protein Synthesis, summary…
Animations
• DNA Replication review
• Transcription & Translation
Practice with Amino Acids
• What is the Amino Acid for :
– AUG
– CCU
– UGG
– AGU