3. Cellular Genetics
3.7. Mitosis
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Mitosis is the process of cell division. After the DNA has been replicated in the S phase of the cell cycle, the cell enters mitosis.
- One cell → two cells
- o → 0 → 8 → oo 😉
After the DNA has been replicated, the cell enters mitosis.
Chromosomes, mitotic chromosomes, and sister chromatids
These concepts are easily confused:
| Concept | Explanation |
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Don't confuse chromosomes, mitotic chromosome (metaphase chromosomes), and sister chromatids!
Interphase – S phase
- The DNA is copied (replicated).
- The centrosome is replicated.
 The DNA and the centrosome are copied during the S-phase in the interphase. |
 Mitotic chromosomes become visible during prophase. |
Prophase
- The chromatin starts to condense (pack).
- Mitotic chromosomes are formed.
- Nuclear membrane dissolves.
- Centrosomes start to move away from each other.
Structure of the (mitotic) chromosome
The DNA is wound two times around histones, and packed tightly into mitotic chromosomes.
The chromatin is very densely packed in mitotic chromosomes.
Metaphase
Nuclear membrane completely dissolved.
Mitotic chromosomes tightly packed, in the equatorial plane = metaphase plate.
- Complete mitotic spindle formed.
 Metaphase. |
 Anaphase. |
Anaphase
Sister chromatids are pulled towards each pole.
Telophase & cytokinesis
New nuclear membrane starts to form.
Chromosomes are unpacked again, relaxed chromatin forms.
Two new cells form ⇒ cytokinesis.
 Telophase. |
 Cytokinesis. |
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Contents
- 1. The Fundamentals of Life
- 2. Cellular Structure and Function
- 3. Cellular Genetics
- 4. Mendelian Genetics
- 5. Evolution and Systematics
- 5.1. Roadmap to a Theory of Evolution
- 5.2. The Pillars of Evolution
- 5.3. Evidence for Evolution
- 5.4. Convergent and Divergent Evolution
- 5.5. Coevolution
- 5.6. Stabilizing and Disruptive Selection
- 5.7. Speciation
- 5.8. How to Build a Family Tree
- 5.9. The History of Life
- 5.10. The Formation of Life
- 5.11. The Divisions of Life
- 5.12. Plant Systematics
- 5.13. Animal Systematics
- 5.14. Chordate Systematics
- 5.15. Human Evolution
- 6. Ethology and Behavioural Ecology
- 7. Ecology: Systems of Organisms
- 7.1. Ecosystems
- 7.2. Nutritional Chains and Food Webs
- 7.3. Flow of Energy in an Ecosystem
- 7.4. The Water Cycle
- 7.5. The Carbon Cycle
- 7.6. The Nitrogen Cycle
- 7.7. The Phosphorous Cycle
- 7.8. Populations: Size and Growth
- 7.9. Communities. Living Together
- 7.10. Ecological Succession
- 7.11. From Bedrock to Litter
- 7.12. The Lakes
- 7.13. The Oceans and Seas
- 7.14. Climate and Biomes
- 8. Environmental Science
- 9. Viruses and Biotechnology
- 10. Plant & Fungal Physiology
- 10.1. The Organs of the Plants
- 10.2. Plants With and Without Seeds
- 10.3. The Root. How the Plant Absorbs Water and Nutrients
- 10.4. The Trunk and Water Transport
- 10.5. Structure and Function of the Leaf
- 10.6. Photosynthesis
- 10.7. How Plants Grow
- 10.8. How Plants Reproduce
- 10.9. Classification of the Fungi
- 10.10. How Fungi Reproduce
- 10.11. Fungal Parasites and Pathogens
- 11. Human Physiology
- 11.1. Physiology Basics
- 11.2. The Nervous System
- 11.3. The Senses
- 11.4. The Endocrine System
- 11.5. Food and Digestion
- 11.6. The Locomotor System
- 11.7. Gas Exchange and Circulation
- 11.7.1. Respirational Systems
- 11.7.2. Human Respiration
- 11.7.3. Circulation in Different Animals
- 11.7.4. The Human Circulatory System. Heart, Blood Vessels and Blood Pressure
- 11.7.5. Activity in the Capillaries
- 11.7.6. Blood Constituents
- 11.7.7. Blood Groups
- 11.7.8. Coagulation
- 11.7.9. Some Blood Diseases
- 11.7.10. Water Balance. Kidneys
- 11.8. The Immune System
- 11.9. Sex, Love, and STDs