Lecture 3 - Introduction to Nucleic Acids Flashcards
What is the central dogma of molecular biology
DNA Replication > Transcription (to RNA) > Translation (to protein)
What is the general structure of a nucleic acid in DNA?
Sugar with base attached at 1’ and phosphate on 5’, no 2’ OH
What is the difference between DNA and RNA?
RNA has 2’ OH
What is the difference between a nucleotide and nucleoside?
Nucleotide has a 5’ phosphate, nucleoside has 5’ OH
What is the direction of phosphodiester bonds?
5’ to 3’
What charge does this create for the backbone of the DNA molecule?
Negatively charged
What is the general structure of a pyrimidine?
6 member ring with N at 1st and 3rd carbons
What bases are pyrimidines?
Cytosine, thymine, and uracil
What is the different between thymine and uracil?
Thymine demethylated at the 5th carbon = Uracil
What is the general structure of a purine?
6 member ring attached to 5 member ring
What bases are purines?
Adenine and guanine
What are some functions for nucleotides?
Building blocks for nucleic acid polymers (DNA, RNA), energy carriers (ATP, GTP), coenzymes (FAD, NADP), precursors for secondary messangers (cAMP)
How are strands of DNA arranged?
In antiparallel strands with complementary base pairing
Which bases pair with which and with how many hydrogen bonds?
G-C (3 H bonds), A-T (A-U) (2 H bonds)
What are the structural features of B DNA?
Right handed helix, 90 degrees from bp to backbone, 1 turn of helix = 10.5 bp, 34 angstroms, major and minor grooves
What are the two other forms or DNA?
A DNA and Z DNA
Important facts about A DNA?
Right handed, 11 bp/turn, essentially shorter, squater version of B DNA
Important facts about Z DNA?
Left handed, 12 bp/turn, elongated
DNA bending facilitates what…
Protein DNA interactions!
What are some factors in DNA’s denaturation?
Size, GC content, [salt], pH
How is DNA packaged into cells?
Wound around nucleosome (comprised of 8 histone proteins), fold into 30 nm fiber, form loops, and ultimately coil into chromosome.
What is the difference between euchromatin and heterochromatin?
Euchromatin is loosely packed (being transcribed) and heterchromatin is tightly packed.
What causes negative supercoiling? What about positive?
Underwound DNA = negative
Overwound DNA = positive
What enzymes exist to relieve supercoiling?
Topoisomerases
