A1.2 Nucleic Acids Flashcards
Define DNA
DNA is a polymer that is your ‘blueprint’. Contains your genes: a code that determines both your unique and non-unique characteristics. DNA is a biological macromolecule called a nucleic acid. DNA: genetic material of all living things.
Define Nucleotide
The basic unit of a nucleic acid. Large molecules contained in the nucleus of cells, hence the name.
Types of Nucleotide
DNA - Deoxyribonucleic acid
RNA - Ribonucleic acid
They are polymers of nucleotides; formed by long chains of nucleotides.
Components of a nucleotide
A pentose sugar, phosphate group, and a nitrogenous base.
Bonding between nucleotides
Sugar-phosphate bonding: phosphate of one nucleotide can chemically bond with the pentose sugar of another. Referred to as ‘backbones’ of DNA and RNA. Phosphodiester bond.
Names of Nitrogenous bases
Guanine (G), Adenine (A), Thymine (T), Cytosine (C), Uracil (U).
Types of nitrogenous bases
Purine: larger; two rings in structure.
Pyrimidine: smaller; one ring in structure.
Purines pair with pyrimidines.
Pairings of nitrogenous bases
DNA: A and T, C and G.
RNA: A and U, C and G
Diagram of DNA structure
Two antiparallel strands, linked by hydrogen bonding between complementary base pairs.
Differences between RNA and DNA
Pentose sugar: ribose vs deoxyribose.
Number of strands: Single-stranded vs double-stranded connected by hydrogen bonding. Helix shape.
Pentose sugar structure: see notes.
Nitrogenous bases: U vs T.
Role of complementary base pairing
DNA
Diversity of possible DNA base sequences and capacity of DNA for storing information
DNA contains high base sequence capacity and limitless storage capacity: DNA stores information and instructions needed to build complex organisms. DNA has 4 possible bases so information can be stored based on all possible combinations from this sequence; depends on number of bases in chain: 20 bases = 4^20. DNA can be any length so limitless storage. DNA does not take up much space.
Structure of a nucleosome
Consists of eight proteins called histones, giving it a bead like structure. DNA wraps around the histone bead, just shy of two complete times and is supported by another histone protein called H1 which reinforces and secures the bonding of DNA to the histone protein core. Linker DNA joins one nucleosome to the other.
Directionality of DNA and RNA
5’ end: closest to fifth carbon within the sugar molecule.
3’ end: closest to the third carbon within the sugar molecule.
DNA sequence is read from 5’ end to the 3’ end.
Hershey-Chase experiment
In the 1900s scientists did not know if it was nucleic acids or proteins that were the genetic materials. So they experimented using radioactive bacteria
