nucleic acids Flashcards
(53 cards)
levels of structure in nucleic acids
- Primary structure
Order of bases in the polynucleotide sequence
Specifies the genetic code - Secondary structure
Three-dimensional conformation of the polynucleotide backbone - Tertiary structure
Supercoiling of the molecule - Quaternary structure
Interaction with other classes of macromolecules, such as proteins
what are the structure in nucleic acids and proteins
a nucleic acid:
5’ to 3’
a protein:
N terminal to C terminal
monomer of nucleic acid
nucleotides
structure of nucleic acids
nitrogenous base
phosphate group
pentose sugar
Nitrogen-containing aromatic compounds that make up the coding portion of nucleic acids
nucleic acid bases
5 membered ring, polysaccharides
pentose sugar
ribose vs deoxyribose
Ribose
* Present in RNA
* Contains -OH group at carbon
Deoxyribose
* Present in DNA
* Lacks -OH group at carbon 2
Purine or pyrimidine base bonded to a sugar (ribose or deoxyribose)
nucleoside
*lacks phosphate group
Formed when phosphoric acid is esterified with an —OH of the monosaccharide, most commonly either the 3′ —OH or the 5′ —OH
nucleotide
*base + sugar + phosphate
what reaction is a nucleoside formation and how is it formed
condensation reaction
The base is attached to C1′ position of the sugar (β- configuration, pataas)
Formed by the addition of a phosphate group to a nucleoside
nucleotide
*water is released when phosphate is attached to C5’
it is the bond between ribose/ deoxyribose and each base
b-glycosidic bond
DNA vs RNA
- Deoxyribonucleic acid (DNA)
– Found within the cell nucleus
– Stores and transfers genetic information
– Passed from existing cells to new cells during cell division - Ribonucleic Acid (RNA)
– Occurs in all parts of a cell
– Primary function is the synthesis of proteins
3′ —OH of one 2-deoxy-D-ribose is
joined to the 5′ —OH of the next 2-deoxy-D- ribose by a
phosphodiester bond
it consists of a backbone of alternating units of 2-deoxy-D-ribose and phosphate
biopolymer
what is the overall charge of the nucleotide
The nitrogenous base can contribute a +1 charge if it is protonated, and the phosphate groups typically contribute a -2 charge. Therefore, when you consider these charges together, the overall charge of a nucleotide is usually negative (approximately -1), especially when accounting for one phosphate group. If there are multiple phosphate groups (as in ATP, for example), the overall charge would be even more negative. So, in summary, the nucleotide’s typical charge is negative due to the phosphate groups outweighing any potential positive contribution from the nitrogenous base.
a nucleotide chain has directionality
5’ end: free phosphate group
3’ end: free hydroxyl group
Sequence of bases along the pentose-phosphodiester backbone of a DNA molecule
primary structure of DNA
Ordered arrangement of nucleic acid strands
secondary structure of DNA
Three-dimensional arrangement of all atoms of a nucleic acid
tertiary structure of DNA
*referred to as supercoiling
Two polynucleotide chains wrapped around each other
DNA double helix
proposed by James Watson and Francis Crick in 1953
based on X-ray crystallography
how are the base pairs are held together
by hydrogen bonds
- which keeps the 2 strands of DNA aligned
- stabilize the double helix
The two strands run in opposite directions
antiparallel
one from 3’ to 5’ and the other from 5’ to 3’
how does one know if the bases are the most stable or preferred pairs
through x-ray cystography
