4 - STRUCTURE OF NUCLEOTIDES

Adenine

Guanine

Purines that serves as nitrogenous bases in nucleic acids

Cytosine

Uracil

Thymine

Pyrimidines that serves as nitrogenous bases in nucleic acids

Thymine

Nitrogenous base that can only be found in DNA

Uracil

Nitrogenous base that can only be found in RNA

D-Ribose

Pentose sugar present in RNA

2’-deoxy-D-ribose (deoxyribose)

Pentose sugar present in DNA

Nucleoside

Refers to the compound composed of a nitrogenous base linked to a pentose sugar

Nucleotide

Refers to the compound composed of a nucleoside linked to a phosphate group

N-glycosidic bond

Type of bond between the nitrogenous base & pentose sugar

Ester bond

Type of bond between the 5'-OH of ribose & phosphoryl group

Anhydride bond

Type of bond between phosphate units

3’-5’ phosphodiester bond

Type of bond between two adjacent nucleotides in nucleic acids

Nucleotides

Building blocks of nucleic acids

Adenosine triphosphate (ATP)

Most abundant free nucleotide in mammalian cell that is the principal biologic transducer of free energy

Negatively charged

Charge of nucleic acids at physiologic pH

5’ end to 3’ end

Sequence of writing of the bases of a DNA or RNA strand

Adenosine-Thymine

Guanine-Cytosine

Base pairing of DNA bases

3

Number of hydrogen bonds between guanine and cytosine

Antiparallel

Orientation of DNA strands

Chargaff’s Rule

Rule that states that the number of purines = the number of pyrimidines

Z-DNA

Type of DNA that has a left-handed double helical structure, as opposed to the usual right-handed orientation

B-DNA

Most common form of DNA physiologically

A-DNA

Type of DNA found in low humidity and high salt conditions

Histones

Most abundant chromatin protein rich in basic residues

H1

Type of histone seen in linker regions

Pairs of H2A, H2B,

H3, H4

Histone octamers are composed of:

1.75 times

DNA is wrapped around the histone octamer by how many times

Prophase

DNA material condenses during what phase of mitosis

Euchromatin

Less condensed form of chromatin that is transcriptionally active, and stains less densely on microscopy

Heterochromatin

Highly condensed form that is transcriptionally inactive, and stains densely on microscopy

Messenger RNA (mRNA)

Only protein-coding RNA

Messenger RNA (mRNA)

Most heterogeneous RNA

Ribosomal RNA (rRNA)

Most abundant RNA

Transfer RNA (tRNA)

Type of RNA with significant proportions of nucleosides with unusual bases

Small nuclear RNA (snRNA)

Micro RNA (miRNA)

Small interfering RNA (siRNA)

Long noncoding RNA (lncRNA)

Types of RNA involved in gene expression regulation