Download DNA: Transcription & Translation

DNA: Transcription &
Translation
How do we go from
DNA to PROTEIN?
WHAT DO WE NEED?
• DNA
• RNA
– mRNA: messenger RNA
– rRNA: ribosomal RNA
– tRNA: transfer RNA
• Amino Acids Proteins
DNA
• The genetic code or
“blue-print” of life
• Contains the bases
A, T, C, and G to
code for amino acids
DNA/ Genes/ Codons
• DNA is made of approximately 80,000
genes
• Genes are sections of DNA
that code for a single protein
• Codons are a set of 3 bases that code for an
amino acid
RNA
• Polymer of ribonucleotides
– Sugar (ribose)
– Phosphate group
– Nitrogenous base (A, U, C, G)
• Single-strand
• Three types: mRNA, rRNA, tRNA
ROLES OF RNA
• mRNA: transports information from DNA
from the nucleus to the cell’s cytoplasm
• rRNA: (makes up ribosomes): clamps on to
mRNA and reads its information to
assemble amino acids in the correct order
• tRNA: transports amino acids to the
ribosomes to be assembled into proteins
Transcription & Translation
TRANSCRIPTION
• Process in the cell’s
nucleus where
enzymes make an
RNA copy (mRNA) of
the DNA strand
Steps of Transcription
• Separation of Strands:
enzymes unzip DNA in the
bases
• Base Pairing: free RNA
ribonucleotides pair with
complementary DNA bases
– Only happens to ONE strand
of DNA
– Uracil bonds with Adenine of
the DNA
Steps of Transcription (cont’d)
• Ribonucleotides Bond:
ribonucleotides of
mRNA bond due to an
enzyme
• Leaves Nucleus:
mRNA strand breaks
away from DNA and
enters the cytoplasm
(where translation
begins)
Transcription to Translation
Translation
• Process of converting
information in mRNA
into a sequence of
amino acids that will
make a protein
Steps of Translation
• Ribosomes Attach: mRNA
enters the cytoplasm where
ribosomes of rRNA attach to it
• rRNA reads mRNA: rRNA
slides down the mRNA and
signals to tRNA to bring the
right amino acid
– Start codon (AUG) signals
where to begin making the
protein
tRNA
• tRNA has a cloverleaf shape with an
anti-codon attached to
one of the “leaves”
and an amino acid
attached to the “stem”
Steps of Translation (cont’d)
• tRNA brings amino
acids: tRNA with the
correct anti-codon arrives
and temporarily bonds to
the codon of mRNA
• rRNA slides and reads:
rRNA continues to slide
down the mRNA and reads
next codon new tRNA
Steps of Translation (cont’d)
• Amino acids join: an
enzyme joins the amino
acids (of tRNA) with
peptide bonds
– Once joined, the now amino
acid free tRNA detaches
from the mRNA strand
– This process continues until
a stop codon
(UAA/UAG/UGA) is read
Transcription & Translation:
END RESULT
A chain of amino acids joined by
peptide bonds PROTEIN
Transcription & Translation
Sequence
Animation of Protein Synthesis
Protein Synthesis Video