( 3 ) Cellular Reproduction in Plants (Cell Division)

Cellular Reproduction (Cell Division)

A process by which cells reproduce by dividing two daughter cells in the process called cell division.

Cellular Reproduction (Cell Division)

It is also a process by which cells reproduce or duplicate their contents and divide to produce similar content of multiple cells.

Cell Cycle

A series of events that takes place in a cell as it grows and divides.

(Cell spends most of its time in the so called interphase and during this time it grows, replicates its chromosomes and prepares for cell division.)

Resting or Quiscent Phase (G0), Interphase, and M Phase

What are the three (3) cell division phases?

Gap 1 (G1), Synthesis (S), and Gap 2 (G2)

What are thre three (3) sub-phases of interphase?

Karyokinesis and Cytokinesis

What are the two (2) sub-phases in M Phase?

Resting or Quiscent Phase (G0)

What sub-phase is this?

Resting stage; cell is non dividing.

Gap 1 (G1)

What sub-phase is this?

Growth phase: synthesis of amino acids and other biochemicals needed for S phase.

Synthesis (S)

What sub-phase is this?

DNA in chromosomes are replicated.

Gap 2 (G2)

What sub-phase is this?

Synthesis of chemicals for the production of microtubules.

Karyokinesis

What sub-phase is this?

The cell nucleus divides.

Cytokinesis

What sub-phase is this?

The cell itself divides into daughter cells.

Chromosomes

Supercoiled DNA that carry genetic information; they replicate themselves into exact copies and each copy is called chromatid.

Chromatin

A term referring to chromosomes during in their diffuse state.

Non-sister chromatids

Are two chromatids from different chromosomes.

Two identical chromatids

One is an exact copy of the other and each contains one DNA molecule.

P Arm

Short arm structure.

Centromere

Constricted point of the chromosome.

Q Arm

Long arm structure.

DNA Molecule

Long string like DNA molecule formed into a compact structure by proteins called histones.

Mitosis and Meiosis

What are the two types of Cell Division?

Mitosis

Cells that do not participate directly in sexual reproduction.

• Process of cell duplication, from which one cell gives rise to two genetically identical daughter cells and usually occurs in somatic cells.

• This term was given by Fleming in 1882.

Meiosis

Occurs in the sex cells (egg cells in females; sperm cells in men).

• Special type of cell division of germ cells or reproductive cells in sexually reproducing organisms that produces the gametes which include sperm and egg cells or ovum.

• The term was given by Farmer and Moore in 1905.

Alexander Fleming

Who coined the term mitosis in 1882?

Farmer and Moore

Who coined the term meiosis in 1905?

Mitosis

• It occurs in somatic cells.

• Nucleus divides only once.

• It is divided into PMAT.

• Daughter cells are called diploid.

• No crossing over takes place.

• Increase the number of normal cells.

• Involved in healing and growth.

• 2 daugther cells are produced.

• Malfunction results in cancer.

Meiosis

• It occurs in germ cells.

• Nucleus divides twice.

• Meiosis I and II divided into prophase I and II, Metaphase I and II, Anaphase I and II, Telophase I and II

• Daughter cells are haploid.

• Crossing over takes place.

• Produces egg and sperm cells.

• Involved in genetic variations.

• 4 daughter cells are produced.

• Malfunction results in genetic disorder such as Disorder syndrome, Klinefelter’s syndrome and Turner’s syndrome.

Prophase

The nuclear membrane begins to disintegrate nucleoli disappear; DNA begins to supercoil and appear as chromosomes.

Metaphase

Chromosomes appear as sister chromatids attached together at the centromere containing the kinetochore; centrioles appear on both poles of the cell; spindle fibers appear and attach to kinetochores; chromosomes align at the center of the cell.

Anaphase

Sister chromatids are pulled towards opposite poles.

Telophase

The nuclear membrane reappears; the DNA begins to diffuse into the nucleus; nucleoli reappear.

Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis

What are the key events in Prophase 1?

Leptotene

Key events in Prophase 1
Individual chromosomes condense to form visible strands within the nucleus.

Zygotene

Key events in Prophase 1
Homologous chromosomes pair up during synapsis.

Pachytene

Key events in Prophase 1
Crossing over happens.

Diplotene

Key events in Prophase 1
Chromosomes separate a little.

Diakinesis

Key events in Prophase 1
Nucleolus disappear; nuclear envelope disintegrates completely; spindle fibers begin to form.

Spermatogenesis

It produces sperms of generally equal potency.

Oogenesis

It produces one large ovum and three polar bodies.

Alternation of Generations

In plants, an alternation between haploid and diploid stages are regulated by mitotic and meiotic divisions.