Gene Expression Regulation Quiz

Gene Regulation

• Gene regulation involves mechanisms that increase or decrease the production of specific gene products (protein or RNA) in response to various stimuli.
• It is essential for viruses, prokaryotes, and eukaryotes, allowing cells to express proteins when needed, thereby increasing an organism's versatility and adaptability.
• Gene regulation can modulate virtually any step of gene expression, including transcriptional initiation, RNA processing, and post-translational modification of a protein.

History of Gene Regulation

• The first discovery of a gene regulation system is widely considered to be the identification of the lac operon in 1961.

Cellular Differentiation and Morphogenesis

• In multicellular organisms, gene regulation drives cellular differentiation and morphogenesis in the embryo, leading to the creation of different cell types with different gene expression profiles from the same genome sequence.

Regulated Stages of Gene Expression

• Chromatin domains are regulated mostly by histone modification, transitioning from euchromatin to heterochromatin.
• Transcription is regulated by cis/trans systems, including enhancers and silencers.
• Post-transcriptional modification involves polyA tail, capping, and splicing of RNA, as well as RNA transport.
• Translation is regulated by mRNA degradation, which is mediated by small interfering RNA and MicroRNA.

Fetal Development

• The fetal period, which spans from the beginning of the ninth week to birth, is characterized by maturation of tissues and organs, as well as rapid growth of the body.
• Fetal growth is particularly striking during the 3rd, 4th, and 5th months, with an increase in weight most notable during the last 2 months of gestation.
• The weight of the fetus remains tiny during the first 12 weeks and reaches 0.5 kg only at 23 weeks (5 1/2 months) of gestation.
• During the last trimester of pregnancy, the fetus gains weight tremendously, averaging 1.3 kg two months before birth, and 3-3.4 kg at birth.

Regulation of Fetal Growth

• Fetal growth and development are determined by genetic and epigenetic factors, including the maternal internal environment, nutrition, and age.
• Maternal hormones, such as GH, thyroid hormones, insulin, prolactin, and steroid hormones, do not significantly cross the placenta, unless elevated levels interfere with fetal development.
• Fetal growth hormones are secreted by developing cells and tissues, acting on neighboring cells through paracrine effects, stimulating or inhibiting growth.