Mechanisms of Cell Differentiation, Development (2C) - MCAT Biological and Biochemical Foundations of Living Systems

Process by which cells acquire specialized structures and functions. Enables multicellular organisms to develop diverse cell types from a common genome, supporting tissue specialization and function.

Differential gene expression. Different cell types activate unique subsets of genes from the shared genome, leading to specialized proteomes and functions.

Totipotent. Totipotent cells, like the zygote, retain full developmental potential to form an entire organism including placenta.

Multipotent. Multipotent stem cells are lineage-restricted, differentiating into various cell types within a specific tissue or organ system.

Unipotent. Unipotent cells are committed progenitors that maintain self-renewal while producing only one specialized cell type.

Ectoderm, mesoderm, endoderm. These germ layers arise from the blastula and give rise to all tissues and organs in the developing embryo.

Endoderm. Endoderm forms internal linings and glands through morphogenetic movements and inductive interactions in embryogenesis.

One tissue influences the fate of nearby cells via signaling. Induction involves molecular signals from one cell group directing the developmental fate of adjacent responsive cells.

Region that patterns surrounding tissues and establishes body axes. The Spemann organizer secretes signaling molecules to induce neural tissue and establish dorsoventral and anteroposterior axes.

Diffusible signal that specifies cell fates by concentration gradient. Morphogens create positional information, with varying concentrations triggering distinct gene expression and cell fates.

Autocrine signaling. Autocrine signals allow a cell to regulate its own behavior through self-produced ligands binding its receptors.

Paracrine signaling. Paracrine factors diffuse locally to influence neighboring cells, coordinating tissue patterning and differentiation.

Juxtacrine (contact-dependent) signaling. Juxtacrine signaling relies on physical cell-cell contact, enabling precise control of developmental processes like Notch pathway activation.

Specify anterior-posterior body pattern and segment identity. HOX genes encode transcription factors that provide positional identity along the body axis through collinear expression patterns.

Transcription factor that activates a gene network for a cell fate. Master regulators initiate cascades of gene activation, committing cells to specific lineages like muscle or neuron development.

DNA methylation at CpG sites. CpG methylation recruits repressive complexes, maintaining stable gene silencing across cell divisions in differentiated states.

Histone acetylation. Acetylation reduces histone-DNA affinity, opening chromatin for transcription factor access and gene activation.

Parent-of-origin-specific monoallelic gene expression. Imprinting involves epigenetic marks that silence alleles based on parental origin, regulating growth and development genes.

Silencing of one X chromosome in female somatic cells. X-inactivation equalizes X-linked gene dosage between sexes via random epigenetic silencing and Barr body formation.

Post-transcriptional gene silencing via mRNA degradation or translation inhibition. MicroRNAs pair with target mRNAs to recruit RISC, leading to cleavage or translational repression for fine-tuned gene regulation.

Programmed cell death that sculpts tissues and removes unnecessary cells. Apoptosis eliminates excess or damaged cells, shaping structures like digits through caspase-mediated pathways.

Differentiation mainly changes gene expression, not genomic DNA sequence. Cell specialization relies on epigenetic regulation of gene expression without altering the underlying DNA sequence.