Nucleic Acids - DNA and RNA Flashcards
(20 cards)
what are nucleic acids?
large molecules discovered in cell nuclei
two types of nucleic acids?
their roles?
DNA and RNA, both have roles in storage and transfer of genetic information for synthesis of proteins
what elements do nucleic acids contain?
carbon, hydrogen, oxygen, nitrogen and phosphorus
what are nucleic acids formed by?
large polymers formed from many monomers (nucleotides)
three components of a nucleotide:
- phosphate group (PO4^2-)
- pentose monosaccharide sugar (5 carbon atoms)
- nitrogenous base - organic molecule containing one or two carbon rings + hydrogen
how are nucleotides linked together?
condensation reactions - form polynucleotides.
what happens during the condensation reaction of nucleotides?
a condensation reaction occurs between the phosphate group of one nucleotide, and the hydroxyl group on the carbon - 3 of the monosaccharide sugar of another nucleotide
what bonds occur?
phosphodiester bonds (strong and covalent)
what are the result of these bonds?
bases are left as a sugar-phosphate backbone
what ends do polynucleotide have?
3-prime end of C-3 of the deoxyribose/monosaccharide sugar and a 5-prime end of a carbon-5
what bases do the nucleotides in DNA have?
- pyrimidines (thymine and cytosine)
- purines (adenine and guanine)
what is the difference between pyrimidines and purines?
pyrimidines only contain single carbon ring structures while purines are larger bases with double/two carbon ring structures
how many bonds does each base form?
A-T forms two hydrogen bonds
G-C forms three hydrogen bonds
how is DNA structured?
two strands of polynucleotides coiled into a helix making a double helix - held together by hydrogen bonds between the bases - the two parallel strands of prime ends 3-5/5-3 are antiparallel
how many nm is a hydrogen bond?
2.0 nm
how many nm are 10 base pairs equivalent to?
3.4 nm
what is complementary base pairing?
the fact that A-T and G-C will always join with only each other + pyrimidines forming with purines maintains constant distance allowing parallel chains since its small to big
What is RNA (ribonucleic acid)
Why is its role useful?
plays an essential role in the transfer of genetic info from DNA to the enzyme and tissue proteins
due to the fact that DNA is large, a long molecule
so unable to leave the nucleus to transfer into to protein synthesis sites
how is RNA structure/nucleotides different to DNA?
- pentose sugar is ribose rather than deoxyribose
- adenine binds to uracil instead of thymine
- smaller as makes copies of sections of DNA
