Cell cycle
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The document discusses the cell cycle and cell division processes of mitosis and meiosis. It explains that the cell cycle consists of an interphase where the cell grows and prepares for division, followed by the mitotic phase where the cell undergoes mitosis. Mitosis produces two daughter cells identical to the parent cell, while meiosis occurs during sexual reproduction and produces four haploid daughter cells through two rounds of division.
Cell cycle
- 1. “ CELL CYCLE ’’ Submitted by:- • Vagh Sarman • Roll no – 37 • 6th sem, • College of Fisheries • Veraval
- 2. Introduction • The cell is the basic unit of life. • The growth and development of every living organisms depend on the growth and multiplication of its cell . • Organisms grow and repair themselves through the process of cell division .
- 3. Cell cycle : • The cell cycle is a sequence of cell growth and division. • The cell cycle is the period from the beginning of one division to the beginning of the next. • The time it takes to complete one cell cycle is the generation time. • The cell cycle is divisible in to two phases : Inter phase Mitotic phase
- 4. (1) Inter Phase : • Inter phase is the interval period between two succesive cell devision . • The cell prepare for cell devision . • The biologist devide inter phase in to three distinct period . 1) G1 phase : 2) S (synthesis ) phase : 3) G2 phase :
- 6. 1) G1 Phase : • It is the longest phase and is the period of maximum growth of cell .their is no changes in Dna contents of the cell during this phase . 2) S Phase : • In this phase dna molecules of each chromosome replicate by the synthesis of new dna molecules . 3) G2 Phase : • It is pre mitotic phase . This phase is characterised by increase in nuclear volume . • The synthesis of Rna and Protein continues in this phase and cell prepare it self to go in to the mitotic phase .
- 7. (2) Mitosis Phase : o The process of cell division which results in the production of two daughter cells from a single parent cell. o The daughter cells are identical to one another and to the original parent cell. o There are mainly 4 phases in to the Mitosis process : - Pro phase : - Meta phase : - Ana phase : - Telo phase :
- 9. Mitosis :
- 10. (3) Meiosis : • One parent cell produces four daughter cells. • Daughter cells have half the number of chromosomes found in the original parent cell During meiosis, DNA replicates once, but the nucleus divides twice. During meiosis, DNA replicates once, but the nucleus divides twice.
- 11. First devision of Meosis : Prophase 1: Each chromosome duplicates and remains closely associated. These are called sister chromatids. Metaphase 1: Chromosomes align at the center of the cell. Anaphase 1: Chromosome pairs separate with sister chromatids remaining together. Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the chromosome pair.
- 12. Second devision of Meiosis : Prophase 2: DNA does not replicate. Metaphase 2: Chromosomes line up at the center of the cell Anaphase 2: Centromeres divide and sister chromatids move separately to each pole. Telophase 2: Cell division is complete. Four haploid daughter cells are formed.
- 13. Meiosis :
- 14. Meiosis :
- 15. Meiosis Vs Mitosis Meiosis Mitosis Type of Reproduction sexual Asexual Occurs in Humans, animals, plants, fungi. All organisms. Identical . Genetically Different Identical Crossing Over Yes, mixing of chromosomes can occur. No, crossing over cannot occur. Number of Divisions 2 1
- 16. Cont…. Meiosis Mitosis Number of Daughter Cells produced 4 2 Chromosome Number Reduced by half. Remains the same. Cytokinesis Occurs in Telophase I and in Telophase II. Occurs in Telophase. Creates Sex cells only: female egg cells or male sperm cells. Makes everything other than sex cells. Discovered by Oscar Hertwig Oscar Hertwig