Biological and Biochemical Foundations of Living Systems: Content Category 2C

Processes of cell division, differentiation, and specialization
The ability of organisms to reproduce their own kind is the characteristic that best distinguishes living things. In sexually reproducing organisms, the continuity of life is based on the processes of cell division and meiosis.

The process of cell division is an integral part of the cell cycle. The progress of eukaryotic cells through the cell cycle is regulated by a complex molecular control system. Malfunctions in this system can result in unabated cellular division, and ultimately the development of cancer.

In the embryonic development of multicellular organisms, a fertilized egg gives rise to cells that differentiate into many different types of cells, each with a different structure, corresponding function, and location within the organism. During development, spatial–temporal gradients in the interactions between gene expression and various stimuli result in the structural and functional divergence of cells into specialized structure, organs, and tissues. The interaction of stimuli and genes is also explained by the progression of stem cells to terminal cells.

The content in this category covers the cell cycle; the causes, genetics, and basic properties of cancer; the processes of meiosis and gametogenesis; and the mechanisms governing cell specialization and differentiation.

Topic Level Key:

The abbreviations found in parentheses indicate the course(s) in which undergraduate students at many colleges and universities learn about the topics and associated subtopics. The course abbreviations are:
BC = first-semester biochemistry
BIO = two-semester sequence of introductory biology

Please note topics that appear on multiple content lists will be treated differently. Questions will focus on the topics as they are described in the narrative for the content category.

Mitosis (BIO)
  • Mitotic process: prophase, metaphase, anaphase, telophase, interphase
  • Mitotic structures
    • Centrioles, asters, spindles
    • Chromatids, centromeres, kinetochores
    • Nuclear membrane breakdown and reorganization
    • Mechanisms of chromosome movement
  • Phases of cell cycle: G0, G1, S, G2, M
  • Growth arrest
  • Control of cell cycle
  • Loss of cell cycle controls in cancer cells
Biosignalling (BC)
  • Oncogenes, apoptosis
Reproductive System (BIO)
  • Gametogenesis by meiosis
  • Ovum and sperm
    • Differences in formation
    • Differences in morphology
    • Relative contribution to next generation
  • Reproductive sequence: fertilization; implantation; development; birth
Embryogenesis (BIO)
  • Stages of early development (order and general features of each)
    • Fertilization
    • Cleavage
    • Blastula formation
    • Gastrulation
      • First cell movements
      • Formation of primary germ layers (endoderm, mesoderm, ectoderm)
    • Neurulation
  • Major structures arising out of primary germ layers
  • Neural crest
  • Environment–gene interaction in development
Mechanisms of Development (BIO)
  • Cell specialization
    • Determination
    • Differentiation
    • Tissue types
  • Cell–cell communication in development
  • Cell migration
  • Pluripotency: stem cells
  • Gene regulation in development
  • Programmed cell death
  • Existence of regenerative capacity in various species
  • Senescence and aging

To support your studies, see the following video tutorials below from the Khan Academy MCAT Collection. The videos and associated questions were created by the Khan Academy in collaboration with the AAMC and the Robert Wood Johnson Foundation.