Download RNA and Protein Synthesis

Bell Ringer
1. What is the complementary DNA for the
following strand TAC GCA ATG CCT?
2. Where does Protein Synthesis take place
(Hint…Unit 3: Cell Organelles)?
3. If Protein is the “polymer”, what would be it’s
“monomer” (Hint…Unit 2: Macromolecules)?
4. What was the analogy for an Protein
(Hint…Unit 2: Macromolecules)?
Joke of the Day:
Joke of the Day:
RNA and Protein Synthesis
Transcription and Translation
Building Proteins
• Protein Synthesis: Building Proteins
• Gene: A segment of DNA that contains
instructions for making proteins.
• RNA: (Ribonucleic Acid) - a working copy of a
single gene.
RNA
vs
• Sugar = Ribose
• Single Stranded
• Contains Uracil
DNA
• Sugar = Deoxyribose
• Double Stranded
• Contains Thymine
Similarities between RNA and DNA:
Both contain nucleotides made of a Sugar, Phosphate
and Nitrogenous Base!
Both contain Adenine, Guanine and Cytosine!
• Codon: (mRNA) a series of 3 nucleotides that code
for a specific amino acid to be added to the chain.
• UCGCACGGU
Example:
mRNA = UCG-CAC-GGU
tRNA = AGC-GUG-CCA
• Anti-Codon: (tRNA) a group of 3 bases on a tRNA
molecule that are complementary to a mRNA.
3 Types of RNA
• Messenger RNA: (mRNA) Codon - carry
messages from the DNA to the rest of the cell.
• Ribosomal RNA: (rRNA) found in the
ribosomes where proteins are assembled
• Transfer RNA: (tRNA) Anticodon - transfers
each amino acid to the ribosomes as it is
needed
Transcription
• Transcription: Process where sections of DNA are copied
into a complementary strand of mRNA (working copy).
Happens in the nucleus.
• RNA Polymerase: the enzyme that aids in the process of
transcription.
Transcription
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
RNA
DNA
The Genetic Code
• Proteins are made by joining amino acids in long
chains
• Monomer = Amino Acid
• Polymer = Polypeptide (Protein)
• The order of the amino acids determines the
specific Protein.
Using the mRNA wheel to Interpret the
Genetic Code!
• Start in the middle of the
circle and move outward!
• UCG = Serine
• CAC =
• GGU =
• UAA =
 There are 64 codons but
only 20 amino acids. So,
different codons can code
for the same amino acid.
Steps of Translation
• Translation: the decoding of an mRNA message into a
protein.
1. mRNA is transcribed from DNA
2. mRNA attaches to the ribosome
3. As each codon of the mRNA moves through the
ribosome, the correct amino acid is carried in by the
transfer RNA.


Each tRNA has an amino acid attached.
The anticodon on the tRNA matches the codon on the mRNA
4. As each amino acid is carried in, a bond forms between
them and the Protein is assembled.
5. The chain continues to grow until it reaches a stop codon
on the mRNA.
3
5
2
1
6
Peptide Bond
4
4
Nucleus
Messenger RNA
Messenger RNA is transcribed in the nucleus.
Phenylalanine
tRNA
Lysine
mRNA
Transfer RNA
Methionine
The mRNA then enters the cytoplasm and attaches
to a ribosome. Translation begins at AUG, the start
codon. Each transfer RNA has an anticodon whose
bases are complementary to a codon on the mRNA
strand. The ribosome positions the start codon to
attract its anticodon, which is part of the tRNA that
binds methionine. The ribosome also binds the
next codon and its anticodon.
Ribosome
mRNA
Start codon
The Polypeptide “Assembly Line”
The ribosome joins the two amino acids—
methionine and phenylalanine—and breaks the
bond between methionine and its tRNA. The tRNA
floats away, allowing the ribosome to bind to
another tRNA. The ribosome moves along the
mRNA, binding new tRNA molecules and amino
acids.
Lysine
Growing polypeptide chain
Ribosome
tRNA
tRNA
mRNA
Completing the Polypeptide
mRNA
Ribosome
Translation direction
The process continues until the ribosome reaches one
of the three stop codons. The result is a growing
polypeptide chain.
http://www.stolaf.edu/people/giannini/flashan
imat/molgenetics/translation.swf
Bell Ringer:
Use your mRNA wheel and translate the following codons into Amino Acids
AUG AAA GUU GGC CCG CAA CCA UCA UGA
START
(MET)
LYS
VAL
GLY
PRO
GLU
PRO
SER
STOP