All flashcards
Flashcard 1: What term describes a cell that can give rise to all three germ layers but not extraembryonic tissues?
Answer: Pluripotent. Pluripotent cells, such as embryonic stem cells, can differentiate into any cell type of the body but not supportive tissues.
Flashcard 2: What is cell differentiation in multicellular organisms?
Answer: 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.
Flashcard 3: What is the key molecular mechanism that allows different cell types to arise from the same genome?
Answer: Differential gene expression. Different cell types activate unique subsets of genes from the shared genome, leading to specialized proteomes and functions.
Flashcard 4: What term describes a cell that can give rise to all embryonic and extraembryonic tissues?
Answer: Totipotent. Totipotent cells, like the zygote, retain full developmental potential to form an entire organism including placenta.
Flashcard 5: What term describes a stem cell that can produce multiple related cell types within one tissue lineage?
Answer: Multipotent. Multipotent stem cells are lineage-restricted, differentiating into various cell types within a specific tissue or organ system.
Flashcard 6: What term describes a cell that can produce only one mature cell type but can self-renew?
Answer: Unipotent. Unipotent cells are committed progenitors that maintain self-renewal while producing only one specialized cell type.
Flashcard 7: What are the three primary germ layers formed during gastrulation?
Answer: Ectoderm, mesoderm, endoderm. These germ layers arise from the blastula and give rise to all tissues and organs in the developing embryo.
Flashcard 8: Which germ layer primarily gives rise to the epithelial lining of the gut and respiratory tract?
Answer: Endoderm. Endoderm forms internal linings and glands through morphogenetic movements and inductive interactions in embryogenesis.
Flashcard 9: What is induction in embryonic development?
Answer: 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.
Flashcard 10: What is the organizer (Spemann organizer) best defined as in early vertebrate development?
Answer: 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.
Flashcard 11: What is a morphogen in developmental biology?
Answer: Diffusible signal that specifies cell fates by concentration gradient. Morphogens create positional information, with varying concentrations triggering distinct gene expression and cell fates.
Flashcard 12: What type of signaling occurs when a cell secretes a factor that acts on itself?
Answer: Autocrine signaling. Autocrine signals allow a cell to regulate its own behavior through self-produced ligands binding its receptors.
Flashcard 13: What type of signaling occurs when a secreted factor acts on nearby target cells?
Answer: Paracrine signaling. Paracrine factors diffuse locally to influence neighboring cells, coordinating tissue patterning and differentiation.
Flashcard 14: What type of signaling requires direct contact between membrane-bound ligand and receptor?
Answer: Juxtacrine (contact-dependent) signaling. Juxtacrine signaling relies on physical cell-cell contact, enabling precise control of developmental processes like Notch pathway activation.
Flashcard 15: What is the core developmental role of HOX genes?
Answer: 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.
Flashcard 16: What is the best definition of a master regulatory transcription factor in development?
Answer: 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.
Flashcard 17: What epigenetic modification is most associated with long-term transcriptional repression?
Answer: DNA methylation at CpG sites. CpG methylation recruits repressive complexes, maintaining stable gene silencing across cell divisions in differentiated states.
Flashcard 18: What histone modification is most associated with transcriptionally active chromatin?
Answer: Histone acetylation. Acetylation reduces histone-DNA affinity, opening chromatin for transcription factor access and gene activation.
Flashcard 19: What is genomic imprinting best defined as?
Answer: Parent-of-origin-specific monoallelic gene expression. Imprinting involves epigenetic marks that silence alleles based on parental origin, regulating growth and development genes.
Flashcard 20: What is X-inactivation (Barr body formation) best defined as?
Answer: 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.
Flashcard 21: Identify the mechanism: a microRNA binds an mRNA and reduces its protein output.
Answer: 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.
Flashcard 22: What is apoptosis in development primarily used for?
Answer: Programmed cell death that sculpts tissues and removes unnecessary cells. Apoptosis eliminates excess or damaged cells, shaping structures like digits through caspase-mediated pathways.
Flashcard 23: Which option best describes why differentiated cells usually keep the same DNA sequence?
Answer: Differentiation mainly changes gene expression, not genomic DNA sequence. Cell specialization relies on epigenetic regulation of gene expression without altering the underlying DNA sequence.