1.4 - Nucleic Acids Flashcards
nucleic acids
polymers of nucleotides specialized for storage, transmission, and use of genetic information
linear polymer of nucleotides joined together by phosphodiester bonds
nucleotides
composed of a nitrogenous base, a pentose sugar, and one to three phosphate groups
pentose + base = nucleoside
function of phosphate groups
link the 3’ carbon in one sugar to the 5’ in the other sugar
formation of nucleic acids
condensation reaction between the 3’-OH group of one sugar with the 5’-phosphate group of the new nucleotide
synthesized in the 5’ to 3’ direction
purines
fused double-ring structure
adenine and guanine
pyramidines
single ring structure
cytosine, thymine, uracil
complementary base interaction
adenine + thymine = 2 hydrogen bonds
cytosine + guanine = 3 hydrogen bonds
RNA vs. DNA
DNA contains deoxyribose while RNA contains ribose
RNA is single stranded while DNA is double stranded
RNA contains uracil while DNA contains thymine
3-D Structure of RNA
results from the complementary base pairing between different regions on a single RNA molecule
hydrogen bonds
Chargaff’s Rule
in DNA, the amount of purines is equal to the amount of pyrimidines
A=T, G=C
Franklin’s X-ray diffraction data
DNA has a double stranded helix structure with phosphates on the exterior and nitrogenous bases on the interior
Watson and Crick
proposed that DNA was a double-stranded molecule with hydrogen bonding in between complementary base pairs
based on: Chargaff’s rule and Franklin’s data
DNA structure
double stranded helix with the sugar phosphate backbone on the exterior and nitrogenous base pairing in the interior
strands are antiparallel
Central Dogma
describes the flow of biological information in living organisms
DNA to RNA to polypeptide
DNA replication
complementary base pairing provides a simple mechanism
semi-conservative replication
Gene expression
process of translation the information in DNA into functioning molecules within cells
mRNA
synthesized from a DNA template and carries the genetic information for protein production
created in the 5’-3’ direction and complementary and parallel to the template strand of the DNA
codon
three letter units specifiying a single amino acid
start and stop codons
AUG - methionine (start)
UAA, UAG, UGA - stop
