cell reproductio

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Various methods of cell multliplication including budding, fission, mitosis and meiosis

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Slide 1: 

CELL REPRODUCTION

ASEXUALGenetically similar cells :Mitosis : 

ASEXUALGenetically similar cells :Mitosis SEXUAL New genetic combinations Chromosome number reduced to half MEIOSIS

Methods of Cell Reproduction : 

Methods of Cell Reproduction When chromosome number remains the same Fission – Binary = equal halves ( cyanobacteria, bacteria ) Budding – Outgrowths separate =unequal (Saccharomyces :Yeast ) Mitosis – The cell passes through a reular process ( Root tips, vegetative cells) When chromosome number is reduced to half Meiosis: In reproductive cells:anthers and ovules.

Cell Division : 

Cell Division Physical basis of inheritance Cells reproduce identically, yet variations are produced ( new traits ) “Omnis cellula e cellula” All living cells arise from pre-existing cells

The Need for cell to divide : 

The Need for cell to divide Continuation of generations Repetition of cycles of growth and division Balance between nucleo- cytoplasmic ratio.

Continuation of generations : 

Continuation of generations Cells and organisms need to survive generation after generation either without any change compared to parent or Undergo changes in the number of chromosomes

Cell Division : 

Cell Division Binary Fission Budding Mitosis Meiosis

Binary fission : 

Binary fission Bacterial cells showing binary fission

Binary fission: A bacterial cell : 

Binary fission: A bacterial cell A bacillus with constriction in the centre. This deepens and both the parts finally separate Each separated part is a daughter cell.

Yeast bud : 

Yeast bud Observe The bud And The Bud Scar

Budding Yeast : 

Budding Yeast A drawing of the yeast cell with a bud to show internal structure

Pseudomycelium in Yeast : 

Pseudomycelium in Yeast The buds continue to remain attached . A fungal mycelium –like structure is formed.

Cell CycleLife Cycle of a Cell : 

Cell CycleLife Cycle of a Cell Interphase G1, S and G2 Mitosis or mitotic cycle 1.Karyokinesis prophase,metaphase anaphase,telophase 2.Cytokinesis Cell plate Cell furrowing

Slide 14: 

Control of Cell Division and the Cell Cycle Regulated by ‘Growth Factors” – proteins that promote cell division MPF – mitotic promoting factor[protein complexof cdk + cyclin ] MPF is a kinase enzyme, one that switches on/off target proteins by phosphorylating them ATP inactive -------------------active - P ADP MPF – promotes mitosis by phosphorylating other proteins that leads to the destruction of cyclin itself

Slide 15: 

cdk - another cell division control protein – a cyclin dependent kinase active only when bound to cyclin cyclin – a protein whose amount varies cyclically when in high concentrations, binds to cdk makes MPF cyclin + cdk = MPF

Slide 16: 

Hartwell,Timothy Hunt and Nurse shared 2001 NP.

A Chromosome : 

A Chromosome

A chromosome : 

A chromosome

Eduard Strasburger : 

Eduard Strasburger 1875 observed chromosomes 1879 Described Cell Division in Plants 1879 Polygonum type of Embryo Sac 1884 Fertilization in plants

Slide 20: 

W. Flemming (1882) termed the process as MITOSIS The cell enters mitotic phase after sending about 95% of the total time taken for completion of division. Soon after G2 phase mitotic phase starts.

MITOSIS : 

MITOSIS

Slide 22: 

Actual photograph of the root tip of onion showing various stages of mitosis

Slide 24: 

Animal Cell Reproduction (Mitosis) Plant Cell Reproduction (Mitosis)

Interphase - Prophase : 

Interphase - Prophase The nuclear membrane seen, Chromosomes still coiled

Mitotic Prophase : 

Mitotic Prophase

Prometaphase : 

Prometaphase Nuclear membrane disappers,spindle appears, chromosomes move

Metaphase & Anaphase : 

Metaphase & Anaphase

Telophase : 

Telophase

CytokinesisThis is the process of separation of nuclei into two separate cellsIn plants : Cell plate formation In animals : Cell furrow formation : 

CytokinesisThis is the process of separation of nuclei into two separate cellsIn plants : Cell plate formation In animals : Cell furrow formation

Cell Plate Formation in Plant cells : 

Cell Plate Formation in Plant cells

Cell Furrow in Animal Cells : 

Cell Furrow in Animal Cells

Meiosis – The Process : 

Meiosis – The Process

Slide 35: 

The term Meiosis was coined by Farmer and Moore (1905) The end result is the formation of four daughter cells with half the number of chromosomes compared to parent cell. Division occurs in cells with at least diploid chromosome number. This division generally precedes gamete formation in higher plants and in zygote in lower plants.

Slide 36: 

Meiosis is demonstrated the best in anthers and ovules .

Slide 37: 

Various stages of Meiosis in pollen grains

Meiosis Meiosis I : 

Meiosis Meiosis I

Meiosis I prophase I : 

Meiosis I prophase I

Meiosis I Metaphase I : 

Meiosis I Metaphase I

Meiosis I late prophase I : 

Meiosis I late prophase I

Meiosis I Metaphase & Anaphase : 

Meiosis I Metaphase & Anaphase

Meiosis I Metaphase II : 

Meiosis I Metaphase II

Meiosis I Prophase I – Crossing over & Chiasma : 

Meiosis I Prophase I – Crossing over & Chiasma

Meiosis I Telophase I : 

Meiosis I Telophase I

Meiosis II prophase II : 

Meiosis II prophase II

Meiosis II Prophase II : 

Meiosis II Prophase II

Meiosis II Metaphase II & Anaphase II : 

Meiosis II Metaphase II & Anaphase II

Meiosis II Telophase II : 

Meiosis II Telophase II

Oogenesis : 

Oogenesis

Spermatogenesis : 

Spermatogenesis

Spermatogenesis : 

Spermatogenesis

Human Life Cycle : 

Human Life Cycle

Meiosis products : 

Meiosis products

Oogenesis : 

Oogenesis