Skip to content
Login Register

#biological systems

3 public questions tagged with this topic.

Teratogens

Endocrine disruptors primarily interfere with:

Endocrine disrupting chemicals represent diverse xenobiotics that interfere with endocrine system integrity by mimicking natural hormones, blocking receptor binding, altering hormone synthesis, transport or metabolism. They bind nuclear steroid receptors estrogen, androgen, thyroid, progesterone, modulating transcription of hormone-responsive genes governing sexual differentiation, brain organization and metabolism at low ecologically relevant concentrations. Compounds like BPA, DES, atrazine act via these pathways rather than directly on cell migration machinery or DNA replication. Their ability to act at nanomolar affinity explains widespread reproductive abnormalities and developmental anomalies observed after gestational exposure interfering with hormonal functions.

Ref: NCBI Bookshelf, Endocrine Disruption: Mechanisms interfering with hormonal functions.

View Details
Processing of mRNA, rRNA, tRNA

Trans-splicing is commonly seen in

Trans-splicing is process joining exons encoded on different precursor RNA molecules into single mature messenger RNA, contrasting with conventional cis-splicing within same transcript. Widespread in kinetoplastid protozoa Trypanosoma brucei, Leishmania, where spliced leader RNA donor provides thirty-nine nucleotide mini-exon capped at five prime end to all messenger RNAs, enabling polycistronic transcription processing. Requires spliceosome similar machinery using SL RNA as five prime splice site donor. Also observed in nematode Caenorhabditis elegans where about seventy percent of pre-mRNAs receive spliced leader, and rarely in mammals.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 11: Trans-splicing Trypanosoma spliced leader; Alberts et al., Trans-splicing in protozoa

View Details
Thermodynamics

In a biological system, which form of energy is most useful for work?

Gibbs free energy is the scientifically accurate answer to this question. Within the study of Thermodynamics, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of Gibbs free energy directly address what is being asked. Among the other options, Enthalpy, Internal energy, and Entropy do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this topic.

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 1

View Details