Nucleic Acids Flashcards
Nucleotide Structure
Phosphate Group
Pentose Sugar
Nitrogenous Base
Purines and Pyrimidines
Purines: Adenine and Guanine
Pyrimidine: Cytosine and Thymine (Uracil instead of Thymine in RNA)
DNA Structure
Double-stranded molecule made of two antiparallel strands that run in opposite directions
(5’ - 3’) (3’ - 5’)
3’ is where C3 free from bonding
5’ is where C5 is free from bonding to other nucleotides
The two strands are wound together to form a double helix, each strand is made of a nucleotide sequence joined to one another with a phosphodiester bond between the sugar of one nucleotide C3 and the phosphate at the C5 end of another nucleotide in a condensation reaction
This gives an alternating sugar backbone, which adds stability
The 2 strands are linked together by a hydrogen bond with complementary base pairing
Adenine forms two H-Bonds with Thymine
Cytosine forms three H-Bonds with Guanine
DNA Function
Stores, copies, and transmits genetic information that determines an organism’s characteristics
RNA Types
mRNA: Carries genetic information from the DNA to the ribosomes, where proteins are synthesized
rRNA: Forms the core of the ribosomes which are what translates mRNA into proteins
tRNA: Delivers specific amino acids to the ribosomes for the process of protein synthesis
Differences between DNA and RNA
DNA is double stranded
RNA is single stranded
DNA has a deoxyribose sugar
RNA has a ribose sugar
DNA bases are ATCG
RNA bases are AUCG
DNA is long
RNA is short
DNA is found in the mitochondria, chloroplast and nucleus
RNA is found in the cytoplasm
Importance of Complementary Base Pairing
Replication: It allows an exact copy of DNA to be made as each strand acts a template to synthesize new DNA
Gene Expression: Turning on and off a gene based off cell requirements, involves transcription and translation
Diversity of DNA Formula
For every DNA with n base pairs, there is 4^n possible sequences
Codons
A set of three bases that codes for one specific amino acid in all living things
Purines to Pyrimidines Bonding and Helix Stability
Adenine and Guanine are purine bases with two rings of atoms
Cytosine and Thymine pyrimidine bases with only one ring of atoms
Purines always bind to pyrimidines, as a result, the two base pairs are equal, this helps stabilize the DNA structure
Chargaff Rule Reinvented
Cytosine and Guanine are often the same, and Adenine and Thymine are often the same
Nucleosomes
8 Histones wrapped around DNA twice, with one extra H1 histone attached outside to maintain colloidal structure
Importance of Nucleosomes
Help supercoil the DNA for more efficient storage
Help regulate transcription
Hershey Chase Experiment
Identify the source of genetic material and see whether it’s proteins or DNA
