Glossary of cellular and molecular biology (0–L)

Glossary of Cellular and Molecular Biology (0–L)

This glossary provides definitions and explanations of key terms in the field of cellular biology and molecular biology, covering terms from 0 to L. This resource is intended for students, educators, and professionals seeking to understand the fundamental concepts and terminology used in these scientific disciplines.

0–9

• 3' end: The end of a nucleic acid strand that has a free hydroxyl group on the third carbon of the sugar ring. It is the opposite of the 5' end.

• 5' end: The end of a nucleic acid strand that has a free phosphate group on the fifth carbon of the sugar ring. It is the opposite of the 3' end.

A

• Amino acid: Organic compounds that combine to form proteins. Amino acids are composed of an amino group, a carboxyl group, and a side chain specific to each amino acid.

• Apoptosis: A form of programmed cell death that occurs in multicellular organisms, characterized by cell shrinkage, chromatin condensation, and DNA fragmentation.

• ATP (Adenosine triphosphate): A molecule that carries energy within cells. It is the main energy currency of the cell, used to drive various biological processes.

B

• Base pair: A pair of complementary nucleotide bases in a DNA molecule, consisting of adenine paired with thymine and cytosine paired with guanine.

• Biomolecule: Any molecule that is produced by living organisms, including proteins, nucleic acids, carbohydrates, and lipids.

C

• Cell membrane: The semipermeable membrane surrounding the cytoplasm of a cell, composed of a lipid bilayer with embedded proteins.

• Chromosome: A long DNA molecule with part or all of the genetic material of an organism. Chromosomes are located in the nucleus of eukaryotic cells.

D

• DNA (Deoxyribonucleic acid): The molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses.

• Differentiation: The process by which a cell becomes specialized to perform a specific function.

E

• Enzyme: A protein that acts as a biological catalyst, speeding up chemical reactions in the cell without being consumed in the process.

• Exon: A segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence.

F

• Facilitated diffusion: A process of passive transport, with the help of transport proteins, of molecules across a biological membrane.

• Frameshift mutation: A genetic mutation caused by insertions or deletions of a number of nucleotides in a DNA sequence that is not divisible by three.

G

• Gene: A sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.

• Genome: The complete set of genes or genetic material present in a cell or organism.

H

• Helicase: An enzyme that unwinds the DNA double helix during DNA replication.

• Homeostasis: The tendency of a system, especially the physiological system of higher animals, to maintain internal stability.

I

• Intron: A segment of a DNA or RNA molecule that does not code for proteins and interrupts the sequence of genes.

• Isotope: Variants of a particular chemical element that have the same number of protons but different numbers of neutrons.

J

• Junctional complex: A type of structure that connects adjacent cells, including tight junctions, adherens junctions, and desmosomes.

K

• Karyotype: The number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

• Kinase: An enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.

L

• Ligand: A molecule that binds to another (usually larger) molecule, often a protein, to form a complex.

• Lysosome: An organelle in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane.

See Also

• Glossary of cellular and molecular biology (M–Z)

References

• Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell. Garland Science.
• Lodish, H., Berk, A., Kaiser, C. A., Krieger, M., Bretscher, A., Ploegh, H., & Amon, A. (2016). Molecular Cell Biology. W. H. Freeman.