Download From DNA To Protein

From DNA To Protein
Transcription
DNA
double
Structure
stranded
Sugar
deoxyribose
adenine,
guanine,
Nitrogen
cytosine,
bases
and
thymine
• DNA and RNA are both nucleic acids
• mRNA – the messenger RNA; carries the message
from the DNA instructing the ribosome which
sequence of amino acids to bond together
• tRNA – the transfer RNA; brings amino acids
to the ribosome
• rRNA – the ribosomal RNA; with proteins
physically composes the ribosome
• Transcription – the creation of mRNA using
DNA as a template
• Initiation
• RNA polymerase – the enzyme that assists in transcription of RNA from DNA
• Template strand – the strand of DNA that will be
transcribed into RNA during transcription
• Non-template strand – the strand of DNA that is
not transcribed into RNA during transcription
• RNA Polymerase and other biochemicals
separate strands
• Elongation
• RNA Polymerase moves along template strand
• Free-floating RNA nucleotides attach
their counterpart on DNA
• Proceeds from 3’ to 5’ direction
• Longer mRNA is created
• Termination
• mRNA and RNA polymerase detach from DNA
• DNA strands rewind
RNA
single
stranded
ribose
adenine,
guanine,
cytosine,
and
uracil
Biology 6.2 – From DNA To Protein
From DNA To Protein
• Steps for determining mRNA strand given DNA strand
• Step 1 | Identify the template strand.
• Step 2 | Write each complementary nitrogenous base.
• Step 3 | If provided, compare to the non-template strand.
Base on DNA
Template
Base on
Complementary mRNA
Adenine (A)
Uracil (U)
Thymine (T)
Adenine (A)
Cytosine (C)
• Prokaryotic cells lack nucleus
• mRNA can be immediately used for protein synthesis
Guanine (G)
• Eukaryotic cells must transport the mRNA out of the nucleus
• RNA processing – the modification of an initial mRNA transcript to create a
mature, useable transcript
• Pre-mRNA – an immature strand of mRNA formed directly after transcription
• After modification it will be mRNA
• A protective cap is added to 5’ end
• Poly-A tail – a repeating section of adenine molecules attached to the
3’ end of the mRNA molecule during processing
• RNA splicing – removal of introns and joining of exons to create
mature mRNA molecules
• Removes introns – the sections of the mRNA molecule removed
during the RNA processing that do not contain useable code
• Connects exons – the sections of the mRNA
molecule that contain the instructions for
the protein
• Before and after coding segment there are UTRs (untranslated regions)
Guanine (G)
Editing mRNA
Cytosine (C)
Biology 6.2 – From DNA To Protein
From DNA To Protein
Translation
• Translation – the use of the codon sequence in mRNA to generate a protein
• Decoded into groups of three RNA bases
• Codons – a series of three bases on the mRNA molecule
complementary to the anti-codon on the tRNA molecule
• Anti-codons – a series of three bases on the tRNA molecule
complementary to the codon on the mRNA molecule
• Ribosome scans mRNA for start codon, AUG
• Anti-codon of tRNA binds to start codon
• Bases in DNA and bases in mRNA strands are same in all organisms
• Only sequence of bases differs
• Each codon of mRNA “codes” for a particular amino acid or a stop codon
• Genetic code can be translated to determine amino acid sequence for proteins from any section of DNA
• Since all organisms use the same genetic code, a codon table can be used to determine the sequence of amino
acids given a mRNA strand
Biology 6.2 – From DNA To Protein
From DNA To Protein
Protein Folding
• When the polypeptide is terminated from the ribosome, protein
synthesis is completed
• Some polypeptides have amino acids that are removed first,
while others are ready to use immediately after translation
• Some proteins go to Golgi Apparatus for packaging
• Functional proteins show various levels of structure
Biology 6.2 – From DNA To Protein