Download From Genes to Proteins (11

Protein Synthesis
Essential Question
Activating
Strategy
How does DNA code for making proteins (protein synthesis) and
how is this process essential to life?
- DNA codes for making proteins by using mRNA. That is
messenger RNA which is used to synthesize proteins. RNA
and DNA can be very alike and different at the same time.
RNA uses uracil and DNA uses thymine. RNA sequences
match with the DNA sequences and synthesizes RNA. This
process is essential to life because we as human use it to
make sure our bodies aontinue on the same routine and to
make sure we function properly throughout our life time.
DNA complementary base pairs: A to T, C to G
RNA complementary base pairs: A to U, C to G
Transcribe the following DNA strand to RNA: ATGGCTATCTAA
UACCGAUAGAUU
Transcription- the process of making mRNA from DNA’s
instructions
1. Enzymes unzip the molecule of DNA by DNA Replication
2. Free RNA nucleotides attach to one exposed strand of DNA
3. The sugar-phosphate backbone bonds. This time is uses
__ribose_______ instead of deoxy-ribose.
4. The mRNA breaks away as the DNA strands rejoin. The
DNA returns to its _original state_________
5. mRNA leaves the __nucleus_______ and enters the
____cytoplasm___________. It is headed to a
__ribosome________________.
- mRNA carries a genetic message (a sequence of
__nucleotides______________________)
- amino acids make up _the protein_____________
- there are only _20_ common amino acids in the world
Codon = a sequence of 3 nitrogenous bases that math with a
specific amino acid. Ex: ATG
Example: The RNA strand AUGUAAAUU is actually the
following three codons: _AUG__ __UAA__ _AUU__.
The _order____ of the nitrogenous bases in the mRNA determines
the type and order of the __type amino acids______ in a protein.
There are _64___ possible codons but only __20__ Possible Amino
Acids
Start codon = _AUG (Methionine or Met)___
Stop codons = _UAA UAG UGA_
More than one codon can code for the same amino acid BUT for
any one codon, there can only be one amino acid!!!
The genetic code is _UNIVERSAL__. (i.e. all organisms use this
code and follow it to make proteins)
Translation = the process of making proteins from amino acids
using the instructions written on mRNA
Translation happens in the ___cytoplasm_______ at the
__ribosome__________.
1. The strand of mRNA attaches to the __ribosome_____.
2. A __tRNA___ molecule brings the first amino acid to the
mRNA strand that is attached to the ribosome.
3. A tRNA __anticodon_______________ pairs with the first
mRNA codon temporarily. What is the first mRNA codon?
_AUG_____
Anticodon = region of tRNA that is complimentary (or
reverse) to the codon of mRNA. This is where it attaches.
4. _AUG_____ signals the start of protein production.
5. The __ribosomes___ slides along the mRNA to the next
_codon_.
6. A new _tRNA________ carrying an __amino acid_ pairs
with the second mRNA codon.
7. The first and second _amino acid___ bond together in a
__peptide___ bond.
8. This process continues joining amino acids until the
ribosome reaches a _stop___ codon on the mRNA strand.
9. The amino acid strand (now an __amino acid chain____) is
released from the ribosome.
10. Once released the Amino Acid Chain __folds into a protein
(tertiary structure!)
Comparison of Replication and Transcription
DNA Replication
DNA Transcription
1. DNA to DNA
2. DNA is permanently split and now has a
parent and daughter strand
3. Final product prepares cell for division
but remains in the nucleus (b/c DNA never
leaves!)
1. DNA to RNA
2. DNA return to original state
3. Final product shoots out of the nucleus
into the cytoplasm to make proteins at the
Ribosome
Assessment Prompt:
Using the Codon Chart determine the amino acid that matches the given codons below.
ACU- Thr
AUG- Met
CCC- Pro
TAT (AUA) - Ile
GCA- Ala
UGA- Stop
GGU- Gly
CAT (GUA) - Val