DNA Structure (Unit 2) Flashcards
Components of DNA
Phosphate Group
Deoxyribose Sugar
Nitrogenous Base
Types of Nitrogenous Bases
Pyrimidines
Purines
Pyrimidines
Made of one 6 member ring
Cytosine and Thymine
Purines
Made of a 6 member ring fused to a 5 member ring
Structure of Nucleotides
Formed by condensations of pentose sugar, phosphate, and one of 4 bases. Nitrogenous base to C1 of sugar, phosphate to C5 of sugar
How are nucleotides joined?
Phosphodiester linkage
Linkage between C3 of sugar and the phosphate of the next nucleotide.
5’ of one attaches to 3’ of next. When strand is created, they attach in the direction of 5’ to 3’
Double Helix Shape formation
Formed by two strands of nucleotides joined by H bonds
Complimentary base pairing - A + T (two bonds), C + G (three bonds). Always one pyrimidine and one purine.
What is backbone of DNA?
Alternating sugar and phosphate
Double helix turns how often?
10.5 nucleotides
How do strands in DNA run?
Antiparallel. 5’ attaches to 3’
Nucleosome
Basic unit of chromatin organization. Beadlike unit of DNA packing.
Amount of DNA in one cell?
2m
How is DNA wound?
DNA around histone proteins, histones wrap to nucleosomes. DNA is negative, histones are positive so attract to form chromatin. Chain coils to form solenoids, which coil to solenoid loops
Genes
Units of genetic information. Contain information for one polypeptide. Every three is one protein.
Genetic Code
Made of order of nucleotides
