RNA Structure and Functions (Medical Entrance)

The site of mRNA synthesis is nucleus. It is synthesised from DNA template in a process called transcription.

Thymine is absent from RNA. It gets replaced by Uracil in RNA.

tRNA ferries amino acids to ribosomes for protein synthesis. As it functions in transfer of amino acids, it is therefore called transfer RNA.

Being a single stranded structure, it does not follow Chargaff's rules. Double strand is necessary for base pairing, whose rules were formulated by Chargaff.

The site for synthesis of proteins, i.e. ribosomes is synthesised by rRNA.

Hepatitis C is a single stranded RNA virus.

tRNA is a very small molecule and thus, easily solubilises in cytoplasm.

The central dogma of molecular biology explains that DNA codes for RNA, which codes for proteins. Thus, DNA and RNA are functionally linked together by central dogma.

7-Methyl guanosine triphosphate caps the 5' terminal end of mRNA. This cap is involved in recognition of mRNA by translating machinery.

Both 5' cap and 3' tail impart stability to mRNA by protecting it from specific exonucleases.

The 3' end of most mRNA's has a poly A tail. It prevents the attack by 3' exonucleases.

25% of hnRNA is processed to mature mRNA.

Heterogeneous nuclear RNA acts as immediate precursor for synthesis of mRNA. Mature mRNA is formed from hnRNA by capping, tailing, splicing and base modification.

tRNA acts as an adapter for the translation of the sequence of nucleotides of the mRNA into specific amino acids.

Each single tRNA shows extensive internal base pairing and acquires a clover leaf-like structure. The structure is stabilised by hydrogen bonding between the bases and is a consistent feature.

Amino acids bind to acceptor arm of tRNA.

The 3' end of the acceptor arm of tRNA has the sequence CCA. This attachment is done post-transcriptionally.

U1, U2, U4, U5 and U6 are the types of small nuclear RNA. They constitute protein-RNA complex functioning as spliceosome.

siRNA is frequently used to decrease or knock down specific protein levels in lab experiments. siRNA forms perfect RNA-RNA hybrids with mRNA and decreases protein synthesis.

Transcription is the process of transferring information from DNA to RNA.

Small nuclear RNA are involved in mRNA processing and gene regulation.

The smallest RNA is tRNA with molecular weight approximately equal to 10^4. Due to small size, they are easily soluble in cytoplasm.

rRNA is a ribozyme because it performs peptidyl transferase activity.

40S subunit contains only a single 18S RNA.

The length of extra arm differentiates tRNA into class I and class II types. Class I tRNA has a shorter extra arm, i.e. 3-5 base pairs long. Class II tRNA has a longer extra arm, i.e. 13-21 base pairs long.

Anti-codon refers to the sequence of three consecutive bases in tRNA molecule, which specifically binds to a complementary code sequence in mRNA.

TΨC arm is made up of pseudouridine and that is why, it is named TΨC arm. Ψ stands for pseudouridine.

The base sequence of anti-codon arm should be complimentary to mRNA, which is mandatory for translation.

Aminoacyl tRNA synthetase adds amino acids to the acceptor arm.

This is the correct matching as acceptor arm is 7 bp long, anti-codon arm is 5 bp long, DHU arm is 3-4 bp long and class II RNA extra arm is 13-21 bp long.