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Cell division - Coggle Diagram
Cell division
Mitosis and Cytokinesis
Eukaryotes are organisms with cells that have a nucleus and other membrane-bound organelles. Eukaryotes have more than one DNA molecule, and each is condensed into a linear chromosome that is composed of DNA and associated proteins.
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During cell division chromatin condensed into smaller, linear bodies called chromosomes.
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DNA replication produces 2 copies of a DNA molecule, identical in DNA sequence. Each copy is called a sister chromatid. 2 sister chromatid constitute one chromosome. Sister chromatids remain attached at the centromere.
Mitosis: division of the nucleus. Prophase, metaphase, anaphase and telophase
Prophase
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In animal cells a pair of proteins called centrioles separate and move towards opposite poles of the nucleus. Centrioles are absent in plant cells
The chromosomes start to move towards the middle of the nucleus. At the same time, the nuclear membrane is broken down and the chromosomes are released into the cytoplasm of the parent cell.
In the late prophase, the centrioles reach the poles of the cell and synthesis proteins called spindle fibres. Spindle fibres made of microtubule proteins, part of the cytoskeleton attaches to each chromosome at the centromere
Metaphase
Spindle fibres pull chromosome to align in the centre of the cell along the equator. One spindle fibre is attached to each chromosome
Anaphase
The centromere's of the chromosomes are broken down and the sister chromatids are pulled to opposite poles of the cell by contracting spindle fibres. The parent cell begins to elongates in prep for cytokinesis
Telophase
The chromosome decondense and are no longer visible with an optical microscope, and nuclear membrane are assembled around the chromosome forming two daughter nuclei
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Spindle fibres: forms during cell division from the cytoskeleton. One spindle fibre attaches to each chromosomes. Spindle fibres pull apart sister chromatids in anaphase
Binary fission
Prokaryotes are unicellular organisms with cells that lack a nucleus and other membrane-bound organelles. Prokaryotes have a single, circular chromosome positioned in the cytoplasm of the cell in a region called the nucleoid. The chromosome is replicated before the parent cell divides into daughter cells in a process called binary fission
Stages in Binary fission
- DNA is replicated. Both copies are attached to the cell membrane
- The DNA molecules are separated as the cell enlarges, membrane elongates.
- A cross wall forms and the membrane invaginates which divides the cytoplasm in two
- The cross wall completely forms
- Daughter cells separate from each other
DNA replication
cells require DNA for the synthesis of structural proteins, enzymes and functional RNA molecule. DNA replication produces 2 copies of each DNA molecule to provide a complete copy of the genome for each daughter cell. DNA replication doubles the amount of DNA in a cell until these copies are separated into 2 daughter cells.
The essential process required for growth and reproduction in living things. In cell div, a pre-existing cell, called parent cell divides producing two identical cells called daughter cells. In unicellular organisms, cell division produces a new organism (reproduction) and increases the number of individual in a population.
In multicellular organisms, cell division increases the number of cells in the body (growth) as well as replacing older and damaged cells.