BIOL 2120 Study Guide - Genes, Development, and Evolution

Key Concepts in Cell Development and Differentiation

• Cell Fate Specification: The process through which cells adopt specific identities during development.

  • Cells express different genes at different levels; this is not due to the loss of DNA.

• Commitment and Determination:

  • Commitment: Refers to the initial phase where a cell can potentially become various types of cells.
  • Determination: The stage where a cell is restricted to becoming a specific type; a determined cell can still show its fate even when transplanted to a different environment.
  • If a transplanted cell changes fate due to external signals, it was not fully determined.

• Self-Renewal: The ability of stem cells to divide and produce more stem cells, maintaining their undifferentiated state.

• Types of Stem Cells:

  • Embryonic Stem Cells: Pluripotent stem cells capable of becoming any cell type in the body.
  • Pluripotent: Can differentiate into almost any cell type.
  • Multipotent: Limited to differentiating into a select lineage of cell types.
  • Induced Pluripotent Stem Cells (iPSCs): Somatic cells reprogrammed to an embryonic stem cell-like state, allowing them to form various cell types.

Developmental Biology Processes

• Developmental Biology: A field studying the processes involved in the development of organisms.

  • Includes the study of embryos, zygotes, cell division, and differentiation.

• Cell Differentiation: Arises through cell signaling and differential gene expression, where cells develop distinct identities.

  • Signaling pathways lead to changes in gene expression resulting in different cell types.

• Induction: A form of cell-cell interaction pivotal in development, often leading to specialization.

• Programmed Cell Death (Apoptosis): Essential process for removing excess or unneeded cells, shaping the overall organism structure.

Establishing Body Plans

• Pattern Formation: The organization of cells into structured arrangements.

• Body Axes: Defined by three main orientations:

  • Anterior-Posterior (front-back)
  • Dorsal-Ventral (top-bottom)
  • Left-Right

• Concentration Gradients: The distribution of signaling molecules across different regions, providing positional information for development.

• Genetic Regulatory Cascades: Series of gene activations that lead to significant developmental changes and cell fate specifications.

• Hox Genes: Critical in determining the identity of body parts; they show homologous functions across species, illustrating conserved evolutionary processes.

Evolutionary Developmental Biology (Evo-Devo)

• Evo-Devo: The study of how developmental processes influence evolutionary changes in body structures.
  • Mutations in developmental genes can lead to variations in body sizes, shapes, and structures, playing a pivotal role in evolution.

Summary of Concepts

• Development relies on initial cell decisions influenced by signals and gene expression changes.
• Positioning in development is determined through a series of interconnected signaling pathways and genetic influences.
• Evolutionary changes emerge from modifications in developmental gene expression patterns, underscoring the relationship between development and evolution.