Chapter 3 Flashcards
What is one major structural difference between RNA and DNA?
2’ hydroxyl on sugar
This refers to the presence of a hydroxyl group (-OH) on the 2’ carbon of the ribose sugar in RNA, which is absent in DNA.
Which base is found in RNA instead of Thymine?
Uracil
Uracil (U) replaces Thymine (T) in RNA.
What is the typical structural form of RNA?
Single stranded
RNA is generally single-stranded, whereas DNA is typically double-stranded.
What are the eight major types of RNA?
- Ribosomal RNA (rRNA)
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Small nuclear RNA (snRNA)
- Small nucleolar RNA (snoRNA)
- MicroRNA (miRNA)
- PIWI-interacting RNAs (piRNAs)
- Long noncoding RNA (lncRNA)
These different types of RNA play various roles within the cell.
What are two key points for understanding RNA function?
- RNA can form complementary base pairs with other nucleic acids.
- RNA can interact with proteins: Ribonucleoprotein (RNP) particles.
These interactions are crucial for many cellular processes.
How can RNA serve as a scaffold?
RNA can serve as a scaffold upon which proteins can be assembled.
An example includes the signal recognition particle.
Can RNA be catalytic?
Yes, RNA can be catalytic - ribozyme.
Ribozymes are RNA molecules that can catalyze chemical reactions.
What constitutes the primary structure of RNA?
A chain-like molecule composed of subunits called nucleotides joined by phosphodiester bonds.
Each nucleotide consists of a ribose sugar, a phosphate group, and a nitrogenous base.
What are the common bases found in RNA?
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Uracil (U)
These bases are fundamental to RNA structure and function.
What is the secondary structure of RNA characterized by?
The folding of an RNA chain into a variety of structural motifs.
This includes structures like bulges, base-paired helices, and hairpin loops.
What type of double helix does base-paired RNA adopt?
A-type double helix
The presence of the 2’-OH group in RNA hinders the formation of a B-type helix.
What are noncanonical base pairs?
Base pairs that differ from Watson-Crick pairing.
They can widen the major groove and enhance accessibility to ligands or proteins.
What role do noncanonical base pairs play in RNA?
- RNA self-assembly
- RNA-protein interactions
- RNA-ligand interactions
These interactions are essential for the proper functioning of RNA.
True or False: Chemical modification of RNA bases does not affect their hydrogen bonding characteristics.
False
Chemical modifications can change how RNA bases interact with each other.
Fill in the blank: ‘tRNA looks like Nature’s attempt to make RNA do the job of a ______.’
protein
This quote by Francis Crick highlights the functional similarities between tRNA and proteins.
What is the role of Transfer RNA (tRNA) during translation?
tRNA is a critical link between codons carried on mRNA and the amino acid carried by the tRNA.
What are the two main structural forms of tRNA?
Cloverleaf secondary structure and L-shaped tertiary structure.
What is the function of the anticodon loop in tRNA?
It directs binding of the tRNA to the codon through base pairing.
Name three general principles of tRNA structure.
- Modified bases
- tRNA loops each have a separate function
- Coaxial stacking of stems
What is the significance of modified bases in RNA?
More than 100 modified bases exist in RNA, affecting hydrogen bonding characteristics.
Which modified nucleoside was the first to be identified in tRNA?
Inosine (I).
What is the function of the T-loop in tRNA?
Recognition by the ribosome.
What is the function of the D loop in tRNA?
Recognition by the aminoacyl tRNA synthetases.
What role does the anticodon loop play in tRNA function?
It base pairs with the mRNA codon.