Rucete ✏ Campbell Biology In a Nutshell
Unit 2 THE CELL — Concept 12.1 Most Cell Division Results in Genetically Identical Daughter Cells
Cell division is a fundamental biological process that ensures the continuity of life by producing genetically identical daughter cells through precise DNA replication and distribution.
Functions of Cell Division
- Enables reproduction in unicellular organisms
- Supports growth and development in multicellular organisms
- Responsible for tissue renewal and repair (e.g., skin, blood cells)
- Produces two genetically identical daughter cells from one parent cell
Genome and Chromosomes
- A cell’s total DNA is called its genome
- Eukaryotic genomes are organized into multiple linear chromosomes
- DNA is packaged with proteins into chromatin
- Chromatin condenses into visible chromosomes during division
Chromosome Structure
- Duplicated chromosomes consist of two sister chromatids joined at the centromere
- Chromatids contain identical DNA molecules
- Once separated during division, chromatids become individual chromosomes
- Ensures each daughter cell receives a complete set of chromosomes
Cell Cycle Phases
- The cell cycle includes interphase and the mitotic (M) phase
- Interphase (90% of the cycle) has three phases:
- G₁: cell growth
- S: DNA replication
- G₂: preparation for division
- M phase includes mitosis (division of nucleus) and cytokinesis (division of cytoplasm)
Mitosis and Meiosis
- Mitosis produces somatic cells with identical DNA
- Meiosis produces gametes with half the number of chromosomes
- Humans: somatic cells have 46 chromosomes; gametes have 23
- Fertilization restores chromosome number and is followed by mitotic growth
In a Nutshell
Cell division creates two genetically identical daughter cells through a coordinated process of DNA replication, chromosome condensation, and distribution. This process supports growth, repair, and reproduction in living organisms.