NUCLEOTIDES Flashcards
Nitrogen bases present in both DNA and RNA
Adenine
Guanine
Cytosine
Nitrogen bases present in DNA only
Thymine
Nitrogen base present in RNA only
Uracil
Methylation of uracil makes this nitrogen base
Thymine
This is the bond formed between NITROGENOUS base and pentose sugar of a nucleoside
N-glycosidic linkage
This is the bond formed between pentose sugar and PHOSPHORYL group of a nucleotide
Ester bond
This bond allows the addition of more phosphoryl bonds at nucleotides to form di- and triphosphates
Anhydride bond
Most abundant free nucleotide in mammalian cell
Adenosine triphosphate (ATP)
Nucleic acids are polymers of nucleotides that are joined by this bond
3’-5’ phosphodiester bond
Sequence of writing the bases of a DNA
From 5’ end → 3’ end
Determinant of the melting point of DNA
Number of G-C bonds
Orientation of DNA strands
Antiparallel
States that the number of purines = number of pyrimidines
Chargaff’s rule
All types of DNA are right-handed except this type of DNA
Z-DNA (left-handed)
Most common form of DNA physiologically (well-hydrated and w/ low salt concentration)
B-DNA
Type of DNA found in low humidity and high salt concentration
A-DNA
Type of DNA mostly seen in 5’ end of chromosomes
Z-DNA
Most abundant chromatin protein
Histone
Histone seen in the linker region
H1
Composition of the histone octomer (core histones)
Pairs of H2A, H2B, H3, H4
Source of negative charge of DNA
Phosphate groups
Source of positive charge of histones
Lysine (H3, H4) Arginine (H2A, H2B)
Represents the “beads on a string” appearance on electron microscopy
10-nm chromatin fibril
DNA is wrapped by around the histone octomer by this amount
1.75 times
Condensation of DNA to form chromosomes occur during this phase of mitosis
Prophase
The highly condensed chromatin seen in electron microscopy, which is transcriptionally inactive
Heterochromatin
The less condensed chromatin seen in electron microscopy, which is transcriptionally active
Euchromatin
Most heterogeneous RNA
mRNA
Most abundant RNA
rRNA
RNA containing significant proportions of nucleosides with unusual bases
tRNA
RNAs responsible for gene expression regulation
snRNA
miRNA
siRNA
lncRNA