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PROTEIN
SYNTHESIS
From DNA to RNA to Proteins
Genes
• Sections of DNA that controls
making of physical
traits/proteins
Types of RNA
• Messenger(mRNA)-carries
protein making instructions from
DNA.
• Ribosomal RNA (rRNA)- Part of
the ribosome-Makes proteins.
• Transfer RNA (tRNA)- transfers
amino acids (building blocks of
proteins) to the ribosome to
make a protein.
DNA vs. RNA (differences)
• DNA
• RNA
– Sugar (Deoxyribose)
– Sugar (Ribose)
– Phosphate Group
– Phosphate group
– Nitogenous Bases
– Nitrogenous Bases
–A
•A
– T=Thymine
• U=Uracil(Not “T”)
–G
•G
–C
•C
• _Double Stranded
• Single Stranded
• Longer
• Shorter
Protein Synthesis Overview
• 2 Main Processes
– Transcription-_DNA_ copied into mRNA
(nucleus)
– Translation-mRNA made into proteins_
________ (ribosomes in cytoplasm)
Amino acid
Protein
Transcription!
DNA
Ribosome
mRNA
Translation!!!!
tRNA
• http://www.youtube.com/watch?v
=ztPkv7wc3yU
• Transcription video
Transcription
• 1. DNA is unzipped (by RNA polymerase-enzyme) at a gene.
“Promoter” initiates copying.
• 2. ONE strand of the DNA template is transcribed (copied) into
mRNA using complimentary base pairing.
• 3. RNA polymerase reaches “termination Signal”/end of gene.
Stops copying.
Simulation
• http://www.phschool.com/atscho
ol/phbio/active_art/protein_synth
esis/index.html
Transcribe the following DNA strands.
• ATTCGACG
• UAAGCUGC
• TTACCAGC
• AAUGGUCG
• TTAAAACG
• AAUUUUGC
Codon
• 3 consecutive nitrogen bases on
mRNA that specify 1 particular
amino acid.
FLOW OF GENETIC INFO
Genetic TraitBlue eyes
B
A
C
Translation Video
• http://www.youtube.com/watch?v
=B6O6uRb1D38&feature=related
Translation -- The decoding of mRNA into a protein
Nuclear envelope
Amino acid
tRNA
Polypeptide chain
Cell membrane
Transcription/translation video
• http://www.youtube.com/watch?v
=NJxobgkPEAo
Translation
Decode mRNA to
Proteins
Steps of Translation
• 1. The mRNA strand is broken into codons
– (Codon- 3 bases that code for an amino acids.)
Translation
• 2.Ribosome reads the codons
and translates them into
amino acids.
• How??
– Uses the Genetic Code
–Match the first letter
on the left
–Match the second
letter on the top
– Match the third letter on
the right
–Ex: codon AUG
– Amino Acid:
Methionine
• What amino acid goes
with the following
codons:
•
•
•
•
•
•
UGGGAAACAUAGAGCCAG-
Example
Translate and write polypeptide (amino acid) chain
• DNA- AGGCGGAGGCGG
• mRNA-UCCGCCUCCGCC
• Amino Acid-Ser-ala-ser-ala
DNA STRAND (Transcribe, translate, amino acid)
CCATAGCACGTTACAACGTGAAGGTAA
• 3. rRNA sends for the tRNA to bring the correct amino
acids.
• 4.The tRNA anticodons match up with the mRNA
codons
– Ex: mRNA CUG -codon
–
t RNA GAC -anticodon brings the amino acid
methionine attached to it.
• 5.Amino acids are attached to each other making a
protein, until a STOP codon is reached
Translation continued
• 6. Disassembly- Ribosome
complex falls apart. Polypeptide
chain (protein) is released.
• DNA: ACA TTG TAG CAT
• mRNA:
• AminoAcids:
• DNA: TTT TAC TGG CGC GTA
• mRNA:
• AminoAcids:
Protein shape video-honors only
• http://www.youtube.com/watch?v
=lijQ3a8yUYQ
FLOW OF GENETIC INFO
Protein Paths (Protein Synthesis) (p.83)
• 1. Nucleus- DNA copied to RNA
• 2. Ribosomes- RNA attaches to ribosomes (on
ER) for protein synthesis.
• 3. Protein leaves ER and goes to Golgi
Apparatus
• 4. Proteins modified/packaged in Golgi
• 5. Vesicles release proteins out of cell through
cell membrane
A
B
C
D
Which is the correct path of protein synthesis???
Protein Paths (Protein Synthesis) (p.83)
• 1. Nucleus- DNA copied to RNA
• 2. Ribosomes/Rough ER- Synthesize
Proteins (send to Golgi)
• 3. Golgi Apparatusmodifies/packages/sends proteins
• 4. Cell Membrane- carries proteins from
Golgi (in vesicles) to be released
from cell
Path of Proteins-