Transcription and Translation (Shiio) Flashcards
DNA –> RNA
Transcription
Transcription is catalyzed by ________ mostly in _______ (also in ______)
- RNA polymerase
- nucleus
- mitochondria
3 types of RNA
mRNA (messenger), rRNA (ribosomal), tRNA (transfer)
Messenger RNA
Template for translation (protein synthesis)
Transfer RNA
Reads the genetic code in mRNA and transfers the appropriate amino acid to a growing polypeptide chain during translation
Ribosomal RNA
component of ribosome (cellular machinery for translation)
Transcription is ____-dependent synthesis of ____ by ________.
- DNA
- RNA
- RNA polymerase
Transcription occurs in the _____ direction, like DNA polymerase.
5’ to 3’
Unlike DNA polymerases, RNA polymerases do not require a ______.
Primer
_____ base pairs with adenine (A), just as thymine (T) does in DNA.
Uracil (U)
RNA polymerase binds to a specific DNA sequence called ________
and initiates transcription.
Promoter
Inhibitors of transcription
- Actinomycin D
- Rifampicin (Rifampin)
Actinomycin D
- Inserts into double-helical DNA and prevents the movement of polymerase along the template DNA
- Inhibits both prokaryotic and eukaryotic transcription
- Used for chemotherapy of a variety of cancers
Rifampicin (Rifampin)
- Inhibits prokaryotic transcription by binding to prokaryotic RNA polymerase
- Used to treat tuberculosis (Mycobacterium infection)
Most eukaryotic mRNAs have a _____ at the 5’ end
and a ______ at the 3’ end
- 5’ cap
- poly(A) tail
Splicing removes _____ from mRNAs in eukaryotes
Introns
Sequences removed by splicing
Introns
Sequences retained after splicing
Exons
Addition of 5’ cap, splicing, and addition of poly(A) tail all occur in the _______.
Nucleus
________ produces DNA from RNA
Reverse transcriptase
Reverse transcriptase allows the synthesis of
DNA complementary to an mRNA template,
which is called ________.
Complementary DNA (cDNA)
cDNA synthesis by reverse transcriptase is
commonly used to _________.
Clone cellular genes
A set of 3 nucleotides (“_____”) codes for a specific amino acid 4 x 4 x 4 = 64 different codons
codon
Protein synthesis usually starts at an N-terminal methionine encoded by ___ and stops at one of the stop codons (___, ___, or ___).
- AUG
- UAA, UAG, UGA
Codons are read by transfer RNAs (tRNAs), using _______, which are complementary to codons.
anticodons
____ insert appropriate amino acids to a growing polypeptide chain during translation
tRNAs
The same amino acid can be encoded by more than one codons (e.g. UUA, UUG, CUU, CUC, CUA, and CUG all encode leucine). the genetic code is “________.”
Degenerate
Mutation that codes for the same amino acid
Silent mutation