W HAT DO YOU T HINK ?. S TRANGE HUH ? T RANSCRIPTION & T RANSLATION.
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Transcript of W HAT DO YOU T HINK ?. S TRANGE HUH ? T RANSCRIPTION & T RANSLATION.
WHAT DO YOU THINK?
WHAT DO YOU THINK?
STRANGE HUH?
TRANSCRIPTION & TRANSLATION
OVERVIEW
Transcription TranslationDNA RNA
Protein
Characteristics
Make Short Notes
TRANSCRIPTION & TRANSLATION
TRANSCRIPTION
DNA never leaves the nucleus
Proteins are synthesized in the cytoplasm
Therefore a copy of the each gene is made using messenger RNA to carry the message from Nucleus to the Cytoplasm
Transcription Is the synthesis of an RNA molecule with a base pair complementary to a section of DNA
TRANSCRIPTION
Usually only a small part of the DNA molecule is transcribed at one time – a section that codes for making one polypeptide is called a GENE
The process starts by the unzipping of the DNA Helix by the enzyme DNA Helicase which break the H+ bonds
Free RNA nucleotides slot into place against the DNA strand i.e. A-U, G-C
Temporary H+ bonds results to hold the RNA in place and Phosphodiester bonds are created between the RNA nucleotides
TRANSCRIPTION
This process is catalyzed by the enzyme RNA polymerase this also ensures that the sequence of amino acids is correct
This elongation of the mRNA continues until the end of the gene or until a STOP codon (ATT, ATC, ACT) is reached
The DNA may zip back up and the mRNA strand exits the nucleus via the nuclear pore into the cytoplasm
TRANSLATION
Translation is the process by which the code for making proteins (carried by the mRNA) is used to sequence a polypeptide chain
The sequence of codons is carried on the mRNA
The AUG (Methionine ) codon indicates the start of an amino acid sequence
The mRNA is held in a cleft in the ribosome in the cytoplasm
TRANSLATION
A tRNA complementary to the 1st start codon binds to the mRNA (INITIATION)
Each tRNA carries with it a corresponding amino acid
As the triple codons are read, complementary tRNA molcecules with their amino acids bind to the mRNA
Upon completion , each tRNA molecule breaks free leaving behind its corresponding amino acid
TRANSLATION
Peptide bonds form between the amino acids resulting in elongation of the polypeptide
The released tRNA is now available to be reloaded with its complementary amino acid
The polypeptide build up until a STOP codon is reached on the mRNA (TERMINATION)
ANSWERS
ACTIVITY 1
TACCGGGTGTACGGGGTG DNA Coding Strand
AUGGCCCACAUGCCCCAC mRNA Strand
met ala hist met pro hist Polypeptide Sequence
N.B. The anticodons on the tRNA are complementary to the codons on the mRNA
ANSWERS
Assessment
Stage A: Transcription
Stage B: Translation
Outline the Process occurring at Stage A:
It Is the synthesis of an mRNA molecule with a base pair complementary to a section of DNA. Usually only a small part of the DNA molecule is transcribed at one time . The process starts by the unzipping of the DNA Helix by the enzyme DNA Helicase which break the H+ bonds. Free
RNA nucleotides slot into place against the DNA strand.
ANSWERS
Assessment cont’d
Temporary H+ bonds results to hold the RNA in place and Phosphodiester bonds are created between the RNA nucleotides. This process is catalyzed by the enzyme RNA polymerase this also ensures that the sequence of amino acids is correct. This elongation of the mRNA continues until the end of the gene or until a STOP codon (ATT, ATC, ACT) is reached. The DNA may zip back up and the mRNA strand exits the nucleus via the nuclear pore into the cytoplasm
THE END
Thank You