Ribonucleic acid is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes.

1. by Prof. Liwayway Memije-Cruz
Ribonucleic Acid or RNA

2. What is RNA?
• RNA stands for ribonucleic acid.
• It is an important molecule with long
chains of nucleotides.
• A nucleotide contains a nitrogenous
base, a ribose sugar, and a phosphate.
Just like DNA, RNA is vital for living
beings.
• a polymeric molecule essential in
various biological roles in coding,
decoding, regulation and expression of
genes.

3. Differences Between DNA and RNA
o RNA is a single-stranded nucleic acid.
o RNA has a ribose sugar instead of a deoxyribose
sugar like DNA.
o RNA nucleotides have a uracil base instead of
thymine.
• Other than these differences, DNA and RNA are the
same. Their phosphates, sugars, and bases show the same
bonding patterns to form nucleotides and their
nucleotides bind to form nucleic acids in the same way.

5. DNA vs RNA

6. What is a RNA strand?
• Double-stranded RNA
(dsRNA) is RNA with
two complementary
strands, similar to the
DNA found in all cells.
• dsRNA forms the
genetic material of
some viruses (double-
stranded RNA viruses).

7. TYPES OF RNA

8. Messenger RNA (mRNA)
• a subtype of RNA.
• carries a portion of the DNA code
to other parts of the cell for
processing.
• during transcription. During the
transcription process, a single
strand of DNA is decoded by RNA
polymerase, and mRNA is
synthesized.
• Physically, mRNA is a strand of
nucleotides known as ribonucleic
acid, and is single-stranded.

9. Ribosomes: Where the translation happens
• Translation takes place
inside structures called
ribosomes, which are
made of RNA and
protein.
• Ribosomes organize
translation and catalyze
the reaction that joins
amino acids to make a
protein chain.

10. Transfer RNA (tRNA)
• the key to deciphering the code
words in mRNA. Each type of
amino acid has its own type of
tRNA, which binds it and carries it
to the growing end of a polypeptide
chain if the next code word on
mRNA calls for it.
• The correct tRNA with its attached
amino acid is selected at each step
because each specific tRNA
molecule contains a three-base
sequence that can base-pair with its
complementary code word in the
mRNA.

11. Ribosomal RNA (rRNA)
• associates with a set of
proteins to form ribosomes.
• catalyze the assembly of
amino acids into protein chains
• also bind tRNAs and various
accessory molecules necessary
for protein synthesis.
• ribosomes are composed of a
large and small subunit, each
of which contains its own
rRNA molecule or molecules.

12. Translation
• the whole process by which the base sequence of
an mRNA is used to order and to join the amino
acids in a protein.
• The three types of RNA participate in this
essential protein-synthesizing pathway in all cells;
in fact, the development of the three distinct
functions of RNA was probably the molecular key
to the origin of life.

13. RNAs as enzymes
• now known to adopt
complex tertiary structures
and act as biological
catalysts. Such RNA
enzymes are known as
ribozymes
• exhibit many of the features
of a classical enzyme, such
as an active site, a binding
site for a substrate and a
binding site for a cofactor,
such as a metal ion.

14. References:
• https://www.news-medical.net/life-sciences/What-is-RNA.aspx
• http://www.sparknotes.com/biology/molecular/structureofnucle
icacids/section3/
• https://www.nature.com/scitable/definition/mrna-messenger-
rna-160
• https://www.khanacademy.org/science/biology/gene-
expression-central-dogma/translation-polypeptides/a/trna-and-
ribosomes
• https://www.ncbi.nlm.nih.gov/books/NBK21603/
• https://www.hhmi.org/biointeractive/enzymes-are-not-proteins-
discovery-ribozymes