L6: RNA Structure Flashcards
Flow of biological infomation
DNA –(transcription)–> RNA –(translation)–> Protein
Polymer of AA nucleotide sequence of genes determine _____ _____
protein sequence
Protein sequence determines _____ _____ and _____
protein structure, function
Building blocks of RNA and DNA
- Nucleoside: pentose + base
- Pyrimidine type (one ring)
C (cytidine)
T (thymidine)
U (uridine) - Purine (two-ring)
A (adenosine)
G (guanosine)
- Pyrimidine type (one ring)
- Nucleotide: nucleoside + phosphate
Pentose in RNA
Ribose
Pentose in DNA
2-Deoxyribose
Bases in RNA
- Purine
- A (adenine)
- G (guanine)
- Pyrimidines
- U (uracil)
- C (cytosine)
Bases in DNA
- Purine
- A (adenine)
- G (guanine)
- Pyrimidines
- T (thymine)
- C (cytosine)
Condensation reaction
- H20 removed to form the phosphodiester bond
RNA
- single strand polynucleotide
- composed of 4 ribonucleotides
- A, C, G, U
ssDNA is stable in _____ solution, but RNA is not
Alkaline
Why is ssDNA stable in alkaline solution but not RNA?
The 2’-OH group makes RNA unstable in alkaline conditions, because it can attack the phosphodiester bonds of the RNA chain and break RNA into small pieces of nucleotide monomers
DNA vs. RNA: sugar
DNA: Deoxyribose (2’-H)
RNA: Ribose (2’-CH)
DNA vs. RNA: base
DNA: A, C, G, T
RNA: A, C, G, U
DNA vs. RNA: structure
DNA: double strand
RNA: single strand
DNA vs. RNA: size
DNA: large (kb-Mb)
RNA: small (bp-kb)
DNA vs. RNA: stability in alkaline
DNA: stable
- dsDNA denatured at high pH but is not hydrolyzed
RNA: unstable
- hydrolyzed to nucleotides
A single strand RNA molecules can form short stretches of double strands when there are enough intra-molecule _____ _____
base pairing
Base pairing:
- G=C --> forms \_\_\_\_\_ H bonds - U=A --> forms \_\_\_\_\_ H bonds
3, 2
RNA secondary structure
- Are stem-loops and hairpins
- Formed through intra-molecule complementary base pairing
RNA tertiary structure
- 3D sructures (i.e. pseudoknotes found in t/rRNA)
- formed by folding stem-loops and hairpins
Major types of RNA in the cell
- mRNA
- tRNA
- rRNA
- others:
- hnRNA
- snRNA
- miRNA
- siRNA
mRNA
- message RNA
- used as template for protein translation
- linear structure
- (eukaryotic) contains sequences encoding a specific polypeptide
- contains noncoding regions at 3’ and 5’ ends, which help translation
- mainly in cytosol, where translation occurs
- (eukaryotic) has special modifications that are 5’ cap and 3’ polyA, neither modifications are found in prokaryotic or other eukaryotic RNAs
message RNA
mRNA
RNA used as template for protein translation
mRNA
RNA with linear structure
mRNA
RNA in (eukaryotic) that contains sequences encoding a specific polypeptide
mRNA
RNA that contains noncoding regions at 3’ and 5’ ends, which help translation
mRNA