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Protein Synthesis
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BIOLOGY
Protein Synthesis Notes
PROTEIN SYNTHESIS
DNA and RNA
Remember DNA is in the nucleus and cant leave – so how does DNA get to the ribosomes?
RNA
RNA
Types of RNA
RNA are the “workers” for protein synthesis. DNA provides the workers with the instructions for making the proteins and the workers build the proteins amino acid by amino acid (Remember amino acid + amino acid + amino acid = Protein).
3 Types of RNA that makes proteins (Workers in the protein assembly line)
3 Types of RNA that makes proteins (Workers in the protein assembly line)
Transcription
The process by which the DNA message is copied into a strand of mRNA is called transcription. This mRNA is then used for the construction of a protein molecule.
Transcription takes places in the NUCLEUS because DNA cannot leave.
The steps:
mRNA carries the instructions that direct the assembly of a specific protein to a designated area on the ribosome. The instructions are carried in a sequence of three nitrogen bases called a codon.
Transcription takes places in the NUCLEUS because DNA cannot leave.
The steps:
mRNA carries the instructions that direct the assembly of a specific protein to a designated area on the ribosome. The instructions are carried in a sequence of three nitrogen bases called a codon.
Codon Chart
Codon is the code – needed to convert mRNA into protein language. Each codon (3 nitrogen bases) codes for one amino acid. This is the genetic code. The genetic code is universal.
64 possible combinations – (see Table 11.1 in book) – Note some do not code for an amino acid, but provide instructions for making a protein (UAA is a STOP codon indicating that the protein chain ends at that point).
AUG is a START codon as well as the codon for methionine.
Note that more than one codon can code for the same amino acid.
64 possible combinations – (see Table 11.1 in book) – Note some do not code for an amino acid, but provide instructions for making a protein (UAA is a STOP codon indicating that the protein chain ends at that point).
AUG is a START codon as well as the codon for methionine.
Note that more than one codon can code for the same amino acid.
Translation
Once the message has reached the ribosome, the protein is ready to be assembled. The process of building the protein from the mRNA instructions is called translation. The transfer RNA (tRNA) and the ribosomal RNA (rRNA) are involved in translation.
In the cytoplasm, a ribosome attaches to the strand of mRNA like a clothes pin clamped to a close line.
tRNA is responsible for carrying the amino acid acids (the building blocks of proteins) to the ribosome so they can be linked in a specific order that makes up a single protein. Each tRNA attaches to only one type of amino acid (correct translation of mRNA depends on the joining of each mRNA codon with the correct tRNA molecule).
How does this happen? One end of the tRNA carries a three-base sequence called an anticodon, which matches up with a particular codon on the mRNA. They are complementary to each other.
The Translation Process
In the cytoplasm, a ribosome attaches to the strand of mRNA like a clothes pin clamped to a close line.
tRNA is responsible for carrying the amino acid acids (the building blocks of proteins) to the ribosome so they can be linked in a specific order that makes up a single protein. Each tRNA attaches to only one type of amino acid (correct translation of mRNA depends on the joining of each mRNA codon with the correct tRNA molecule).
How does this happen? One end of the tRNA carries a three-base sequence called an anticodon, which matches up with a particular codon on the mRNA. They are complementary to each other.
The Translation Process
The Central Dogma
Crick and Watson had a model for the flow of information in cells. This model incorporates DNA, RNA, and proteins.
DNA may replicate itself
DNA may be transcribed to RNA
RNA may be translated into proteins
RNA and DNA are NOT made from protein
DNA is NOT made from RNA
Called the Central Dogma of Molecular Biology – DNA to RNA to protein
DNA may replicate itself
DNA may be transcribed to RNA
RNA may be translated into proteins
RNA and DNA are NOT made from protein
DNA is NOT made from RNA
Called the Central Dogma of Molecular Biology – DNA to RNA to protein
Summing It All Up!
The genetic code between DNA and protein is in the sequence of nucleotides in DNA within genes.
DNA is transcribed into mRNA
mRNA is translated into a polypeptide with the help of tRNA
tRNA with a specific sequence that matches mRNA, carries the specific amino acid to the ribosome to help form a polypeptide
Ribosomes are the site of protein synthesis.
Transcription involves making a strand of RNA complementary to DNA.
RNA is single stranded-only one strand of DNA is transcribed.
RNA produced is messenger RNA (mRNA) because it carries the genetic message from DNA to the site of protein production.
DNA does not leave the nucleus!!!
this information is used to code for a protein made up of amino acids
if there are 4 letters in DNA language, and there are 20 amino acids that make up proteins
Amino acids are coded for by groups of 3 nucleotides, called CODONS.
Four codons have special functions in the genetic code
DNA is transcribed into mRNA
mRNA is translated into a polypeptide with the help of tRNA
tRNA with a specific sequence that matches mRNA, carries the specific amino acid to the ribosome to help form a polypeptide
Ribosomes are the site of protein synthesis.
Transcription involves making a strand of RNA complementary to DNA.
RNA is single stranded-only one strand of DNA is transcribed.
RNA produced is messenger RNA (mRNA) because it carries the genetic message from DNA to the site of protein production.
DNA does not leave the nucleus!!!
this information is used to code for a protein made up of amino acids
if there are 4 letters in DNA language, and there are 20 amino acids that make up proteins
Amino acids are coded for by groups of 3 nucleotides, called CODONS.
Four codons have special functions in the genetic code
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