Download Transcription/Translation Notes Handout

Name:_______________________________________________________________
8.4: Transcription
Transcription converts a gene into a single-stranded RNA molecule.
Gene: A specific region of DNA that codes for a particular protein
RNA carries DNA’s instructions.
• The central dogma states that information flows in one direction ______________________________________
• Through _______________________________________, DNA changes into RNA.
• Through _______________________________________, RNA changes into a Protein.
• The central dogma includes three processes: Replication,
Transcription, Translation
DNA contains the instructions to make proteins. RNA is a ___________
between DNA and proteins.
RNA differs from DNA in three major ways.
1. DNA has a deoxyribose sugar, RNA has
a _________________ sugar.
2. RNA has uracil instead of thymine
(found in DNA)
-________________________________________
3. DNA is a double stranded molecule,
RNA is _____________________.
Transcription copies a piece of DNA (a gene)
to make a strand of RNA.
How does Transcription work?
1. Transcription is catalyzed by
st
RNA polymerase.
-RNA polymerase and other
proteins form
_______________________________________. The transcription
complex recognizes the start of a gene and unwinds a
segment.
5.
2. _____________ strand of DNA serves as a template
-Nucleotides pair with one strand of the DNA.
-RNA polymerase bonds the nucleotides together.
-The DNA helix ___________________ as the gene is
transcribed.
3..The RNA strand _____________________________________ from
the DNA once the gene is transcribed.
Transcription makes three types of RNA.
– Messenger RNA (mRNA) carries the message that will be translated to form a _______________.
– Ribosomal RNA (rRNA) forms part of _______________________________ where proteins are made.
– Transfer RNA (tRNA) brings __________________________________________(protein building blocks)
from the cytoplasm to a ribosome to build the protein.
The transcription process is similar to replication.
-Transcription and replication both involve complex enzymes and complementary _________________.
*Both processes take place in the nucleus
-The two processes have different end results.
* Replication copies all the ________________; transcription copies a gene.
* Replication makes _____________ copy; transcription can make many copies.
8.5 Translation
Translation converts an mRNA message into a polypeptide, or protein.
Amino acids (protein building blocks) are coded for by mRNA base
sequences.
• A _______________________ is a sequence of three nucleotides that codes for
an amino acid.
• The genetic code matches each codon to its amino acid or function.
• three ______________ codons signal the end of a chain of amino acids.
• one ________________ codon, codes for methionine and to start translation
Reading frame: multiple codons that code for a chain of amino acids.
*A change in the order in which codons are read changes the resulting _________________ – this is why
having a clear “start” and “______________” is important.
***** Common (universal) language: Regardless of the organism, codons code for the same
_______________________________.
What happens during translation?
*Amino acids are linked to become a protein.
• An ___________________________________ is a set of three
nucleotides that is complementary to an mRNA codon.
• An anticodon is carried by a _________________. tRNA
carries amino acids from cytoplasm to the
____________________to become part of the growing protein.
EXAMPLE:
mRNA codon=GUU
tRNA anticodon=CAA
Amino acid=Valine
Where does translation happen?
• Ribosomes are the site of protein synthesis. They are located in the _________________________ and on
the rough ER.
• Ribosomes are made of rRNA & ______________________. They have a large & small subunit.
• Helps form ________________________________ between amino acids.
How does translation happen?
1. For translation to begin, ____________ binds to a start codon (Met in picture) and signals the ribosome to
assemble.
-A complementary tRNA molecule binds to the exposed ____________ (Leu in picture), bringing its
amino acid close to the first amino acid.
2. The ribosome helps form a polypeptide bond between the amino acids.
-The ribosome pulls the _____________________ strand the length of one codon.
3. The now empty tRNA molecule exits the ribosome.
-A complementary tRNA molecule _______________________________________ exposed codon.
-Once the stop codon is reached, the ribosome _______________________ the protein and disassembles.
Overall
Translation:
Transcription and Translation: