How does a cell grow and divide to maintain the continuity of life?
Explain the cell cycle, including interphase and mitosis (PMAT), the role of mitosis and binary fission in growth and reproduction, and how loss of cell-cycle control leads to cancer (GSE SB1.b).
A Georgia Milestones Biology EOC answer on the cell cycle: interphase and the phases of mitosis (PMAT), how mitosis and binary fission produce identical cells for growth and reproduction, and how a mutation in cell-cycle control genes leads to cancer.
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What this topic is asking
Standard SB1.b asks you to explain the role of cellular reproduction (binary fission, mitosis, meiosis) in maintaining the continuity of life. This page covers the cell cycle and mitosis: the phases (interphase then PMAT), what mitosis is for (growth and repair, asexual reproduction), how prokaryotes divide by binary fission, and how losing control of the cycle leads to cancer. Meiosis is covered separately under heredity.
The cell cycle
A cell spends most of its life in interphase, growing, carrying out its functions, and (in the S phase) replicating its DNA so that each daughter cell can receive a complete copy. Only after the DNA is copied does the cell divide.
Mitosis: PMAT
Mitosis is the division of the nucleus into two identical nuclei. It has four phases, remembered as PMAT:
- Prophase. The chromosomes condense (become visible), and the nuclear membrane begins to break down.
- Metaphase. The chromosomes line up along the middle (equator) of the cell.
- Anaphase. The sister chromatids separate and move to opposite ends (poles) of the cell.
- Telophase. Two new nuclei re-form, one at each end.
After telophase, cytokinesis splits the cytoplasm, producing two genetically identical daughter cells, each with the full chromosome number.
Binary fission in prokaryotes
Prokaryotes (bacteria) do not use mitosis. They reproduce asexually by binary fission: the single circular DNA is copied, and the cell simply splits into two identical cells. It is faster and simpler than mitosis but, like mitosis, produces identical offspring (clones), which is why bacterial populations can grow so quickly.
The cell cycle and cancer
The cell cycle is normally regulated by genes that act at checkpoints, telling a cell when to divide and when to stop. This control matters: it keeps growth orderly and repairs damage at the right rate.
Try this
Q1. List the four phases of mitosis in order. [2 points]
- Cue. Prophase, metaphase, anaphase, telophase (PMAT).
Q2. Explain how a mutation can lead to cancer. [2 points]
- Cue. A mutation in the genes that regulate the cell cycle can disable the checkpoints, so the cell divides without control, forming a tumor that may become cancer.
Exam-style practice questions
Practice questions written in the style of GaDOE exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Milestones (style)1 marksWhat is the main purpose of mitosis in a multicellular organism? (A) to produce gametes for reproduction (B) to produce genetically identical cells for growth and repair (C) to halve the chromosome number (D) to create genetic variationShow worked answer →
A 1-point selected-response item on the purpose of mitosis.
The correct answer is B. Mitosis produces two genetically identical cells with the full chromosome number, which an organism uses for growth and repair (and for asexual reproduction). A and C describe meiosis (which makes gametes and halves the chromosome number), and D also describes meiosis (variation). The clue is "identical cells" with the "full" chromosome number, which is mitosis.
Milestones (style)2 marksDrag and drop. Place the four phases of mitosis in the correct order: anaphase, metaphase, prophase, telophase.Show worked answer →
A 2-point technology-enhanced (drag-and-drop) ordering item.
The correct order is prophase, metaphase, anaphase, telophase (remembered as PMAT). In prophase the chromosomes condense; in metaphase they line up at the cell's middle; in anaphase the sister chromatids separate to opposite ends; in telophase two nuclei re-form, followed by cytokinesis splitting the cell. Full points require the exact PMAT order.
Related dot points
- Construct an explanation of how cell structures and organelles (nucleus, cytoplasm, cell membrane, cell wall, chloroplasts, lysosome, Golgi apparatus, endoplasmic reticulum, vacuoles, ribosomes, mitochondria) interact as a system to maintain homeostasis (GSE SB1.a).
A Georgia Milestones Biology EOC answer on the eukaryotic organelles as a structure-and-function system: the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, chloroplasts, lysosomes, vacuoles, membrane, and cell wall, and how they work together to maintain homeostasis.
- Explain the process of DNA replication, including its semiconservative nature, the role of complementary base pairing, and why accurate copying matters (GSE SB2.a).
A Georgia Milestones Biology EOC answer on DNA replication: the semiconservative model, how the strands separate and serve as templates, the role of complementary base pairing and DNA polymerase, when replication happens, and why accuracy matters.
- Explain the role of meiosis in producing gametes and in generating genetic variation through crossing over and independent assortment (GSE SB3.a).
A Georgia Milestones Biology EOC answer on meiosis: how it halves the chromosome number to make gametes, the difference from mitosis, and how crossing over, independent assortment, and random fertilization create genetic variation.
- Illustrate the organization of interacting systems in multicellular organisms and explain how they maintain homeostasis through feedback, including the levels of organization from cells to organ systems (GSE SB4.a).
A Georgia Milestones Biology EOC answer on the organization of interacting body systems: the levels of organization (cells, tissues, organs, organ systems), how the major systems interact, and how negative feedback maintains homeostasis, with examples such as temperature and blood sugar regulation.
- Construct an argument that mutations (changes in DNA sequence and chromosomal alterations) may result in phenotypic variation, and classify gene mutations as beneficial, harmful, or neutral (GSE SB2.b).
A Georgia Milestones Biology EOC answer on mutations: point mutations (substitution, insertion, deletion), frameshift effects, chromosomal mutations, causes (mutagens and replication errors), and how mutations can be beneficial, harmful, or neutral sources of variation.
Sources & how we know this
- Biology Georgia Standards of Excellence (GSE) — Georgia Department of Education (2024)
- Georgia Milestones Biology EOC Assessment Guide — Georgia Department of Education (2024)