RNA 1 Flashcards
RNA structure
4 nucleotides linked by phosphodiester bond
Purines
Pyrimidines
Ribose
RNA base pairs or nucleotides
Purines Adenine and guanine
Pyrimidines Cytosine and uracil
Which RNA base pair together
Complementary base pairing
A=U; G≡C
RNA purines
Adenine and guanine
RNA Pyrimidines
Cytosine and uracil
Synthesis of mRNA from DNA template
Transcription
remember this is same language so transcribing
3 things required for transcription
DNA template (single strand)
RNA polymerase
Ribonucleoside triphosphates
Adenine, Guanine, Cytosine, Uracil
Composition of ribonucleotide
ribose (5C), nitrogen base, phosphate group
Translation
different languages
mRNA (nucleic acid) into protein
not same so need to translate
First amino acid in translation
fmet – formyl methionine
mRNA translated in codons
by ribosomes
what is a codon
Three consecutive nucleotides
Sequence of codons (mRNA) determines
amino acid sequence (protein)
Translation begins at
start codon: AUG (methionine) (usually)
Translation ends at
UAA, UAG, UGA
3 steps in translation
initiation, elongation, termination
Genetic code
1) Universal
2) Redundant (degenerate)
3) 64 codons (61 “sense”; 3 “nonsense”)
4) Codon (mRNA) = 3 nucleotides
tRNA (anticodon) carries
amino acid (3’ end) look at slide 8 or page 4 bottom.
Bacteria (70S ribosome)
30S: 16S rRNA* + 21 proteins
50S: 5S and 23S rRNA + 34 proteins
Archaea (70S ribosome)
30S: 16S rRNA* + 25 proteins
50S: 5S and 23S rRNA + 39 proteins
One has 5.8S rRNA
50-70 proteins depending on species
Eukarya (80S ribosome)
40S: 18S rRNA + ~33 proteins
60S: 5S, 5.8S, and 28S rRNA + ~49 proteins
What is the general process of translation?
Initiation, elongation, termination
What are some differences between prokaryotic and eukaryotic translation?
eukaryotic translation (cytoplasm) &transcription (nucleus) asynchronous process prokaryotic translation/transcription is synchronous process. (same time)
The process by which the base sequence of an RNA molecule is used to direct the synthesis of a protein is called \_\_\_\_\_\_\_\_. A) replication B) transcription C) reverse transcription D) translation
D) translation
During translation elongation, which event happens last?
A) A tRNA carrying an amino acid binds to the A site.
B) A peptide bond forms.
C) A tRNA molecule translocates from the A site to the P site.
D) A tRNA molecule translocates from the P site to the E site.
D) A tRNA molecule translocates from the P site to the E site.
Which is true regarding translation in bacteria?
A) Translation begins with formation of the 30S initiation complex.
B) Translation ends when the Shine-Dalgarno sequence is reached.
C) The 70S ribosome is composed of a 20S and 50S subunit.
D) All of the choices are correct.
A) Translation begins with formation of the 30S initiation complex.
In \_\_\_\_\_\_\_\_, ribosomes can attach to the mRNA and begin translation even though transcription has not been completed. A) bacteria B) eukaryotes C) fungi D) protozoa and some plants
A) bacteria
The process by which the base sequence of all or a portion of a DNA molecule is used to direct the synthesis of an RNA molecule is called \_\_\_\_\_\_\_\_. A) replication B) transcription C) reverse transcription D) translation
B) transcription
bacterial \_\_\_\_\_\_\_\_ is the nontranscribed region of the DNA to which RNA polymerase binds in order to initiate transcription. A) operon B) operator C) promoter D) initiator
C) promoter
Choose the correct order of proteins that function in the initiation, elongation, and termination stages of DNA replication.
A) DnaA, DNA polymerase III, DNA polymerase I, DNA ligase
B) DnaA, DNA polymerase I, DNA polymerase III, DNA ligase
C) DNA polymerase III, DNA polymerase I, DNA ligase, DnaA
D) DNA polymerase I, DnaA, DNA polymerase III, DNA ligase
A) DnaA, DNA polymerase III, DNA polymerase I, DNA ligase
RNA polymerase III of eukaryotes is responsible for transcribing \_\_\_\_\_\_\_\_. A) rRNA B) mRNA C) tRNA D) All of the choices are correct.
C) tRNA
three starts with T so tRNA is III
RNA polymerase II of eukaryotes is responsible for transcribing \_\_\_\_\_\_\_\_. A) rRNA B) mRNA C) tRNA D) All of the choices are correct.
B) mRNA
