Nucleic Acids and Energy Molecules Vocabulary

Chemical Structure and Components of Nucleic Acids

• Nucleic Acid Definition:

  • Nucleic acids are biological polymers composed of monomers known as nucleotides.

• Nucleotide Composition:

  • Each individual nucleotide is composed of three primary chemical units:

  • A phosphate group ($\text{phosphat}$).

  • A sugar molecule (forming the base-sugar nucleoside backbone).

  • A nitrogenous base (also designated as $\text{@nurogen}$ / nitrogen-containing bases).

• Nitrogenous Base Classes:

  • Pyrimidines:

  • Structurally defined in notes as containing rings (noted as 2 rings).

  • Cytosine ($C$, also recorded as cybosine).

  • Thymine ($T$): Found exclusively in Deoxyribonucleic Acid ($\text{DNA}$).

  • Uracil ($U$): Found exclusively in Ribonucleic Acid ($\text{RNA}$).

  • Purines:

  • Structurally defined as containing 2 rings.

  • Adenine ($A$).

  • Guanine ($G$, also recorded as guaning).

• Nucleoside Structure and Phosphorylation States:

  • Nucleoside:

  • Consists of a nitrogenous base bound to a sugar side group ($HO$ group attached).

  • Nucleoside Monophosphate:

  • Consists of a nucleoside bound to a single phosphate group ($HO-P-O-$).

  • Nucleoside Diphosphate:

  • Consists of a nucleoside bound to two linked phosphate groups ($HO-P-O-P-O-$).

  • Nucleoside Triphosphate:

  • Consists of a nucleoside bound to three linked phosphate groups ($HO-P-O-P-O-P-O-$).

Nucleic Acid Polymers, Linkages, and Higher-Order Structures

• Phosphodiester Linkages:

  • Nucleotides are joined covalently by a phosphodiester linkage (or phosphodiester bond) to form linear strands of nucleic acid.

• Deoxyribonucleic Acid (DNA):

  • Secondary Structure: Formed as a two-stranded double helix.

  • Complementary Base Pairing:

  • Adenine binds specifically with Thymine ($A-T$).

  • Cytosine binds specifically with Guanine ($C-G$).

  • Strand Attachment: Hydrogen bonds ($\text{hydrogen bond}$) hold the two strands together.

• Ribonucleic Acid (RNA):

  • Secondary Structure: Exists as a single-stranded nucleic acid (one strand).

Cellular Energy Carriers: ATP and ADP

• Adenosine Triphosphate (ATP):

  • A high-energy nucleoside triphosphate molecule consisting of an adenosine moiety attached to three phosphate groups.

• Adenosine Diphosphate (ADP):

  • A nucleoside diphosphate molecule consisting of an adenosine moiety attached to two phosphate groups.

Cell Organization and Subcellular Structures

• Prokaryotic Cell Features:

  • Fimbriae: Surface structures that assist bacterial prokaryotes with movement and adherence.

• Eukaryotic / Animal Cell Architecture:

  • Membrane Bilayers:

  • Both the nuclear envelope and the plasma membrane are constructed from a phospholipid bilayer.

  • Nuclear Structure and Transport Mechanics:

  • Nuclear Envelope: Surrounds the nucleus and contains selective openings known as nuclear pores.

  • Nuclear Localization Sequence (NLS):

    • An amino acid sequence tag on target proteins that specifies import into the nucleus.

  • Importin:

    • A nuclear transport receptor protein that binds to the Nuclear Localization Sequence ($\text{NLS}$) to mediate protein import through nuclear pores.

  • Nuclear Lamina:

    • A protein network acting like internal scaffolding to keep the nucleus round and maintain structural integrity.

  • Intranuclear Features:

  • Chromatin: The intranuclear material consisting of $DNA$ and protein.

  • Nucleolus: A specialized nuclear sub-region responsible for making ribosomal RNA ($rRNA$).

  • Endoplasmic Reticulum (ER):

  • Rough ER: Membrane-bound compartment associated with ribosomes and protein processing.

  • Smooth ER: Membrane-bound compartment involved in lipid synthesis and metabolic processes.