Mitosis and cell cycle

• Cell cycle describes the sequence of cell growth and cell division
• Interphase, mitosis and cyrokinesis are the three stages of the cell cycle
• Interphase involves cell growth, synthesis of organelles, dna replication and Proof reading of genetic information
• Proof reading genetic information involves checking for mutations
• Cytokinesis is when the cytoplasm divides between the daughter cells
• Interphase comes between successive cell division and Is not part of mitosis
• Proliferation is the production of new cells that also grow
• Interphase contains gap phases: G1 is the cell hrowgh and synthesis of new organelles, S is dna replication and Proofreading, G2 is the additional growth and preparation for division
• Cell cycle checkpoints control the mechanisms of the cell cycle, they verify if processes at that each stage have been completed correctly
• G1 checkpoint may involve verifying size, nutrients and dna integrity
• Spindle checkpoint involves examining if all sister chromatids are correctly attached to spindle microtubeles
• The G0 phase is when a cell moves out of the cell cycle, this can be temporary or permanent
• Examples of cells that may be in G0 are differentiated, specialised cells or damaged dna or rbc
• Mitosis is the division of a cell that results in 2 daughter cells having an exact copy of the dna of a parents cell
• The purposes of mitosis/cell cycle are development and growth, replacing old or worn out cells, production of some eukaryotic cells
• Viruses do not divide or enter the cell cycle
• Prokaryotes undergo binary fission
• Mature red blood cells do not go through the cell cycle
• Mitosis is a sequence of events where replicated dna condenses into visible chromatids which are alignee separated and compartmentalised into 2 new daughter cells
• Movement of chromosomes is orchestrated by specialised structures called microtubules (spindle fibres)
• First stage of mitosis is prophase: replicated sister chromatids become visible, the nucleus and nuclear envelope disappear, centrioles form and move to opposite poles, and spindle fibres form organised as a spindle apparatus
• Second phase of mitosis is metaphase: spindle fibres draw sister chromatids by their central centromere to the equator, spindle checkpoint occurs, ensuring all attached to 2 spindle fibres
• The third stage of mitosis is anaphase: sister chromatids separate from each other and pulled to the opposite poles by spindle fibres, this requires atp
• In anaphase any microtubules not attached to chromosome elongate and pull apart seperating the poles and making the cell longer
• The last stage of mitosis is telophase: spindles break down, new nuclei form, 1 for each set of chromosomes, chromosomes also begin to decondense and return to their stringy form
• Cytokinesis follows mitosis, it is contractile hence pinching the cell in 2, it can also start at early as anaphase
• In prophase chromates condense, they are visible as sister chromatids due to the replicated dna
• In metaphase chromosomes attach to spindle fibres by their centromere and align along the equator of the cell
• In anaphase the centromere divides and chromosomes are pulled to opposite poles randomly