RNA structure Flashcards
Structure of RNA
*Like DNA, RNA is made up of nucleoside (polymers) monophosphates (NMPs)
* Consists of a base, a sugar and a phosphate group
* There are two important differences though:
- Nitrogenous bases
DNA (A C G T)
RNA (A C G U)- uses uracil instead of thymine.
- DNA has a hydrogen group while RNA has a hydroxyl group at the 2’ carbon position. hence the name deoxyribose.
Diagram of the differences between RNA and DNA.
What does RNA stand for?
what does DNA stand for?
Ribonucleic acid
Deoxyribonucleic acid
RNA single ring
RNA double ring
pyrimidine(single)= C U T (CUT the PY)
Purine (double ring)= A G (pure as gold)
what are the complementary base pairing in RNA?
Adenine (A) and Uracil (U):
- A pairs with U through two hydrogen bonds.
Cytosine (C) and Guanine (G):
- C pairs with G through three hydrogen bonds.
Why is Uracil used instead of Thymine in RNA.
- Uracil is quicker to produce than thymine (less energetically expensive).
- Thymine is more stable and needed in DNA, but RNA is short-lived and doesn’t need to be so stable.
- RNA appeared first in evolution (with uracil). As the DNA molecule evolved, it needed to be more stable,
and thymine was the solution.
How is the structure of thymine different to uracil.
Methyl group added to
uracil makes thymine.
Uracil= simple structure = carbonyl group (C=O) and an amino group (NH2) attached to a pyrimidine ring= no methyl group.
Thymine= similar to uracil but has a methyl group (CH3) attached to the carbon atom at position 5 of the pyrimidine ring.
The nucleic acid polymer of RNA is composed of a sequence of nucleotides.
what are the key features of nucleic acid polymers?
In both DNA and RNA, the backbone consists of alternating sugar (deoxyribose in DNA and ribose in RNA) and phosphate groups.
The sugar-phosphate backbone is constant and provides the framework for the nucleic acid.
The bases vary among the nucleotides. The specific sequence of these bases encodes genetic information.
The order of the bases along the nucleic acid strand determines the genetic instructions for building proteins and regulating biological processes. This sequence is read in sets of three bases (codons), each specifying a particular amino acid or signaling the end of protein synthesis.
why is RNA LESS stable than DNA.
Single stranded structure: - - RNA= single-strand structure= unstable= ,more susceptible to damage. DNA (double-stranded and more robust due to its helical structure).
Protection in the DNA:
The bases in DNA are protected inside the double helix with phosphate groups on outside, which helps shield them from damage.
Chemical reactivity:
RNA contains -OH group on the 2’ carbon of its ribose sugar= more reactive and prone to hydrolysis, leading to bond breakage.
In contrast, DNA has a hydrogen (H) at the 2’ position of its deoxyribose sugar, making it less reactive and more stable.
Hydrolysis of RNA:
The presence of the 2’ hydroxyl group can facilitate the cleavage of the phosphodiester bond, which links nucleotides together in the RNA strand. This reaction can lead to the breakdown of the RNA molecule.
what does RNA form?
Due to base pairing between complementary bases within the same strand, RNA can fold back on itself, forming secondary structures (double-stranded segment). This secondary structure is known as STEM.
what happens when the base sequence not match during formation of secondary structures?
Sequences that don’t match can lead to non-canonical pairing, resulting in loops or bulges.
Loops= segments where there’s an unpaired nucleotide, often forming a hairpin or a larger loop structure.
Bulges: when there are mismatched or unpaired nucleotides within a paired region, leading to irregularities in the helical structure.
REWORD SO THAT IS MORE UNDERSTANDBLE
what are the types of loops. DIGARMS
Hairpin Loop
Multi-branched Loop
stem
Bulge Loop
Interior Loop
Complexity of RNA
RNA molecules can have a level of complexity in their structure like some proteins. This complexity arises from their ability to fold into intricate three-dimensional shapes driven by base pairing and other interactions.
e.g. human telomerase, an enzyme that adds repetitive sequences to the ends of chromosomes, includes both RNA and protein components.
what are the different types of proteins.?
Messenger RNA (mRNA)
Transfer RNA (tRNA).
Ribosomal RNA (rRNA).
Small nuclear RNAs (snRNAs)
Messenger RNA (mRNA)
- Carries genetic information from DNA to the ribosome, where proteins are synthesized.
PRODUCT OF GENE TRANSCRIPTION.
- It is synthesized during transcription and serves as a template for protein synthesis during translation.
-mRNA is edited following transcription and
exported out of the nucleus before being translated into protein.
