Lecture 3: Intro To Nucleic Acids Flashcards
Which viruses have dsDNA?
PAPILLOMA, herpes, smallpox
Frequently transmitted
In which direction is mRNA read during translation?
5’ –> 3’
What’s one type of virus which has ssDNA?
Bacteriophage
What’s a virus which has dsRNA?
Rotavirus
Which viruses have +sense ssRNA?
HEPATITIS C, dengue, rubella
Which viruses have -sense ssRNA?
EBOLA, measles, mumps, influenza
What is the difference between a nucleotide and a nucleoside?
Nucleoside lacks phosphate
Nucleotide = base + sugar + phosphate
Key difference between RNA and DNA?
RNA lacks 2’ -OH
H is susceptible to attack by base
Between which functional groups do phosphodiester bonds form? What is the directionality of the chain?
5’-OH and 3’-OH
5’ –> 3’
What are the differentiating functional groups on the pyrimidine bases?
Cytosine: NH2
Thymine: CH3
Uracil: =O
One ring
What are the differentiating functional groups on the purine bases?
Adenine: NH2
Guanine: =O
Two rings
What are the nucleoside and nucleoside monophosphate (NMP) forms of adenine?
Adenosine
Adenylate
What are the nucleoside and nucleoside monophosphate (NMP) forms of guanine?
Guanosine
Guanylate
What are the nucleoside and nucleoside monophosphate (NMP) forms of cytosine?
Cytidine
Cytidylate
What are the nucleoside and nucleoside monophosphate (NMP) forms of uracil?
Uridine
Uridylate
What are the nucleoside and nucleoside monophosphate (NMP) forms of thymine?
Thymidine
Thymidylate
What are the modifications made to bases in DNA, and what do they do?
5-methyl-cytosine –> packaging of chromosomal DNA, X inactivation
5-hydroxymethylcytosine –> may regulate gene expression by demethylating DNA, lots in CNS
What are the base modifications in RNA and what do they do?
Hypoxanthine: purine biosynthesis, anticodon of tRNA
Pseudouracil: tRNA
N6-methyladenosine: mRNA; gene expression and splicing
List 5 cellular functions of nucleotides
- Building blocks for DNA, RNA
- Carry energy
- Part of coenzymes (FAD, NAD(P)+, coenz A
- Precursors for 2nd messengers (cAMP, cGMP)
- Intermediates in biosyn
How many h-bonds bonds form between AT and GC?
AT 2
GC 3
What is the form and handedness of DNA?
B form
Right handed double helix
How many base pairs are in one turn of the helix?
- 5 base pairs
3. 4 angstrom
What is Chargaff’s rule?
AT and CG pair
Why are the major and minor grooves created?
Sugar phosphate backbones are unevenly spaced
