2.6 Structure of DNA and RNA Flashcards
two types of nucleic acids
DNA = deoxyribonucleic acid
RNA = ribonucleic acid
function of nucleic acids in living organisms?
make up DNA and RNA which are molecules that contain genetic information and are used to make proteins
Nucleic acids
polymers of nucleotides formed via condensation reactions
A nucleotide
a single unit of a nucleic acid
Nucleotides consist of three parts
Sugar – pentose sugar (ribose or dexyribose)
Phosphate group – acidic, negatively charged
Base – contains N, single ring (pyrimidine) or double ring (purine)
To link nucleotides together, condensation reactions form…
a covalent bond between phosphate group (C5) of one nucleotide and the hydroxyl group (C3) of the other nucleotide
- phosphodiester bond
- sugar-phosphate backbone
Successive condensation reactions between nucleotides results…
formation of a long single strand
dna vs rna (nitrogenous bases)
DNA: adenine (A), cytosine (C), guanine (G), thymine (T)
RNA: adenine (A), cytosine (C), guanine (G), uracil (U)
dna vs rna (sugar)
Different sugar found in each
Both pentose sugars
Deoxyribose has one fewer O
Strands: DNA vs RNA
DNA contains two polymers of nucleotides (2 strands) which are complementary and anti-parallel
RNA contains one polymer of nucleotides (1 strand)
The two strands of DNA are
anti-parallel. This means that the strands are parallel, but run in opposite directions
Each DNA strand has a
5’ end (phosphate) and a 3’ end (OH)
The strands are held together by…
hydrogen bonds between the complementary bases (A=T, G≡C)
Each polynucleotide chain (strand) consists of
a chain of nucleotides bonded covalently.
As the polynucleotide chain lengthens, the atoms that make up the molecule will arrange themselves in an optimal energy configuration.
This position of least resistance results in the double-stranded DNA twisting to form a double helix with approximately 10 - 15 bases per twist.
