RNA and its Types Flashcards
What is ribonucleic acid (RNA)?
-RNA is polymer of nucleotide
-single strand
-these are transcribed from DNA template
What are the three types of RNA?
-messenger RNA (mRNA)
-ribosomal RNA (rRNA)
-transfer RNA (tRNA)
What is messenger RNA (mRNA) and what role does it play?
It is a single strand of variable length. It takes the genetic message from the nucleus to the ribosome in the cytoplasm to form a particular protein.
On what does the length of messenger RNA depends?
It depends on the size of the gene as well as the protein for which it carries the message.
What percentage of RNA does the mRNA contain ?
mRNA is about 3% to 4% of total RNA in the cell.
What is codon of genetic codes?
It is a sequence of three nucleotides on messenger RNA that codes to form a single amino acid.
What does the ribosome consist of?
It consist of rRNA AND PROTEIN.
What is rRNA transcribed by?
The ribosomal RNA is transcribed by genes present on the DNA by several chromosome.
Why is it called ribosomal RNA?
It is called ribosomal RNA because it eventually becomes the part of ribosome.
What is the size of rRNA?
It is the largest of all the types of RNA.
What is the rRNA is packed with?
It is packed with a variety of proteins into ribosomal subunits.
What is the rRNA is packed with?
It is packed with a variety of proteins into ribosomal subunits.
What is the percentage of RNA does rRNA have?
80% of the total RNA contents of a cell are in rRNA.
What is the role of ribosomal RNA?
It provides a platform for synthesis.
What is the smallest of the RNA molecules?
Transfer RNA (tRNA)
How many nucleotides does a tRNA molecule consist of?
75 to 90 nucleotides
What type of structure does tRNA exhibit in some regions?
It is single strand but show duplex appearance due to complementary bases bonding
What is the two-dimensional shape of
tRNA ?
A flat cloverleaf shape
What base does the 5’ end of tRNA always terminate in?
Guanine base
What is the base sequence at the 3’ end of tRNA?
CCA
Where is the amino acid attached on the tRNA molecule?
At the 3’ end
What is the characteristic of the nucleotide sequence of the rest of the
tRNA molecule?
The nucleotide sequence is variable
How many loops does tRNA have?
Three loop
What is the composition of the middle loop in all tRNA?
It is composed of 7 bases, with the middle three forming the anticodon
What is the function of the anticodon in tRNA?
It is complementary to a specific codon of mRNA
What does the D loop in tRNA recognize?
The activation enzyme
What does the Theta (0) loop in tRNA recognize?
The specific place on the ribosome for binding during protein synthesis
How many tRNA molecules are there for each of the 20 amino acids?
At least one tRNA molecule for each amino acid
How many tRNA molecules are there for each of the 20 amino acids?
At least one tRNA molecule for each amino acid
How many tRNA molecules have been identified?
Sixty tRNA molecules
How many tRNA molecules have been identified?
Sixty tRNA molecules
How many different kinds of tRNA molecules are found in human cells?
About 45 different kinds of tRNA
molecules
What is the role of tRNA in protein synthesis?
It transports a specific amino acid from the cytoplasm to the surface of the ribosome
What is anticodon?
Three nucleotides on tRNA that fits perfectly into the mRNA codon that codes for a amino acid on tRNA
Why messenger RNA has the least percentage of RNA in it?
Because it will decompose after it completes function
Why messenger RNA has the least percentage of RNA in it?
Because it will decompose after it completes function
