Ch 8 Transcription and Translation Flashcards
*Where does Transcription occur?
Nucleus
What is the product of Transcription?
mRNA from DNA
What does mRNA do after it is created?
Exits nucleus through pores to bind with ribosomes
*Where does Translation occur?
Cytoplasm
What are genes made up of?
DNA sequences
What Pyridines does mRNA have?
Cytosine
Uracil
*What is a codon?
Sequence of a specific 3 nucleotides that form a unit of genetic code
What is a gene?
Template for mRNA
What does RNA polymerase do?
Makes complimentary RNA to DNA
How many strand(s) participate in transcription? What (is it) (are they) called?
1 strand
Template strand
What do tRNA’s do?
Transfer amino acids
What proteins start transcription?
Transcription Factors (TF’s) RNA polymerase can’t start without them
What is the name for the strand that undergoes transcription?
Template strand
What is the name for the strand that does NOT undergo transcription?
Message strand
How do you differentiate the RNA strand from the Message strand of DNA?
Replace all the T’s with U’s
How is RNA synthesized?
5’ Prime to 3’ Prime
How many phases does Transcription have? What are they?
3 Phases
- Initiation
- Elongation
- Termination
What happens in initiation of Transcription (1st step)?
RNA polymerase binds to promoter and unwinds DNA
What happens in Elongation of Transcription? (2nd step)?
RNA polymerase separates 2 strands and figures out which strand will be the template strand
What happens in Termination or Transcription (3rd step)?
RNA transcript is freed from template
Transcription finishes
What determines which DNA strand will be the template?
Promoter called the “TATA Box”
They have a rich A - T sequence
-EVERY GENE HAS PROMOTERS
*In Eukaryotic cells what happens to mRNA before translation?
Processed first; G cap and Poly A tail added
In the processing before translation what happens to mRNA?
G cap is added (5’ Prime cap)
Poly A tail added (3’ Prime end) (100-300 A’s added)
They are added for protection
What are introns?
Spacers that don’t code (Later removed by splicers)
What are exons?
Nucleotide sequences that remain in a mature mRNA
What do spliceosomes do?
Cut out Introns and stick together Exons
*What does alternate splicing produce?
Different mRNA’s and proteins
i.e proteins in brain, heart, and liver
*Why are introns and exons so important?
Allow splicers to form different proteins from a single gene
What is the product after processing?
RNA
What are the 3 phases of Translation?
- Initiation
- Elongation
- Termination
How many amino acids are there? How many different synthetases are there?
20 of both
What is an “anti codon”?
Codon complementary to the original codon
What is a ribosome made up of?
RNA (Ribosomal RNA)
*Name the 2 Ribosome subunits
Large subunit
Small subunit
*What are the 3 binding sites on a large ribosomal subunit?
Exit
Peptidyl tRNA
Aminoacyl tRNA
*What happens in the Exit site of a large ribosomal subunit?
tRNA without amino acids exits
*What happens at the Peptidyl tRNA site of a large ribosomal subunit?
Transfer occurs to build polypeptide chain; Polypeptide bonds are MADE here
*What happens at the Aminoacyl tRNA site of a large ribosomal subunit?
tRNA with amino acid enters
*What is the Start codon in Eukaryotes?
AUG
*What is the first amino acid (initiator tRNA)?
Methionine
*What is ALWAYS the initiator tRNA in Eukaryotes? Where does it attach?
Methionine; Attaches to AUG start codon at the “P” Peptidyl Site
What happens in Elongation of Translation?
Building of polypeptide chains
*What are the 3 STOP codons?
UAA
UAG
UGA
What are Release Factors?
RNA and protein that recognize stop codons (Look like tRNA; Don’t have amino acid)
What is a polysome? Hint: Poly-Some
Multiple ribosomes on a single RNA
What is the product of TransLation?
Polypeptide chain
What is the whole purpose of transcription and translation
Make protein from mRNA
Does RNA Polymerase need a primer like DNA Polymerase?
No; Does not require a primer like DNA polymerase needs
How is termination of transcription determined?
Specific DNA sequence
*What is the first tRNA called?
Initiator (Methionine) different shape than other tRNA’s
*Where does the INITIATOR tRNA enter?
Peptidyl tRNA site the only one to do so
Where are the Exit, Peptidyl tRNA and Aminoacyl tRNA sites located?
Large ribosomal subunit
Translocation, the transferring the products of Peptydyl tRNA (Met, Try, etc) require what?
GTP energy
Where does “Protein finishing” take place?
ER and Golgi apparatus called “Post-translation”