Download Differences between DNA and RNA • Ribonucleic acid is similar to

RNA | MCAT 2015
Differences between DNA and RNA
• Ribonucleic acid is similar to
DNA, but has a few differences
• Firstly, RNA is single-stranded,
whereas DNA is double-stranded
RNA vs. DNA: Number of Strands
DNA consists of 2 complementary strands,
whereas RNA generally exists as a single strand.
•
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Also illustrated in this diagram,
RNA uses the nitrogenous base
uracil in place of DNA’s thymine
Thirdly, the 2-carbon on DNA’s
pentose sugars are deoxygenated
o Hence the name
‘deoxyribonucleic acid’
In RNA, the 2-carbons of those
pentose sugars have hydroxyls
RNA vs. DNA: Deoxygenation of Pentose’s 2Carbon
In RNA, the 2-carbon of each nucleotide’s
pentose sugar has a hydroxyl group. In DNA,
those hydroxyl groups have been removed.
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Lastly, though DNA is confined
to the nucleus, RNA can pass
through nuclear pores and move
into the cytosol
The Three Types of RNA
• Messenger RNA (mRNA) –
carries DNA-encoded
information into the cytosol,
where it can be translated into
proteins
o Remember, the DNA
can’t leave the nucleus,
so it needs a messenger
(mRNA) to deliver the
code to the cytosol
• Ribosomal RNA (rRNA) –
combine with certain proteins in
the cytosol to form ribosomes
o Ribosomes are cellular
machines used to produce
proteins
More on this later
• Transfer RNA (tRNA) –
sequesters amino acids from the
cytosol and brings them to the
ribosomes
o At the ribosomes, they
are used to build proteins
Overview of RNA
• DNA is transcribed into RNA in
the nucleus
o rRNA leaves the nucleus
and joins proteins in the
cytosol, thereby forming
the ribosomes
o mRNA leaves the nucleus
and carries the DNA code
for proteins to the
ribosomes, where the
proteins will be produced
o tRNA leaves the nucleus
and brings cytosolic
amino acids to the
ribosomes, where they are
used in protein
construction
• By transcribing RNA, DNA can
remain in the nucleus while its
code is brought into the cytosol
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