Cells and control study guide

Mitosis is a fundamental biological process of cell division, ensuring growth, repair, and tissue maintenance in multicellular organisms, and reproduction in some unicellular ones. It is a critical part of the cell cycle, the series of events that take place in a cell leading to its division and duplication. The eukaryotic cell cycle involves two main phases: interphase and the mitotic phase. Interphase, often considered the 'resting phase', is a period of significant growth and DNA replication, preparing the cell for division. It consists of three sub-phases: G1 (First Gap), S (Synthesis), and G2 (Second Gap). During the S phase, the cell's DNA is duplicated, resulting in chromosomes consisting of two identical sister chromatids. The mitotic phase includes mitosis (nuclear division) and cytokinesis (cytoplasmic division), culminating in the formation of two genetically identical daughter cells. Mitosis itself is divided into distinct stages: prophase, metaphase, anaphase, and telophase, each with specific events vital for accurate segregation of duplicated chromosomes. Overall, mitosis maintains the chromosome number from parent to daughter cells, ensuring genetic continuity.

Percentile charts are essential tools used by healthcare professionals to monitor the physical development of infants, children, and adolescents. These charts display a range of measurements, such as height, weight, and head circumference, for a specific age and gender, allowing for comparison with a large reference population. Each curved line on the chart represents a specific percentile, indicating what percentage of children in the reference population have measurements below that line. For instance, the 50th percentile represents the average, while the 90th percentile means that 90% of children of that age and gender have a smaller measurement. By plotting a child's measurements over time, healthcare providers can observe their growth trajectory. A child consistently tracking along a specific percentile line is typically considered to be growing well. A significant deviation from their established growth curve, such as a sudden drop or rise across many percentiles, can signal a potential health concern requiring further investigation. These charts help identify issues like faltering growth, overweight, or underweight, enabling timely interventions.