BRAINCAKECell Division
Revision notes for Cell Division in OCR Biology A (H020). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- The Cell CycleCells undergo a regular cycle of growth and division.
- InterphaseDuring interphase, the cell grows and carries out various metabolic processes.
- MitosisMitosis is important in growth, repair and asexual reproduction.
- Control of the Cell CycleThe cell can divide only if DNA replication is free of errors or has been repaired, if the cells have grown to the right size, if the chromosomes…
- CancerCancer is a group of diseases caused by uncontrolled mitosis.
- ChromosomesChromosomes are made of long thin molecules of DNA coiled around packaging proteins called histones.
- Prophase1.
- MetaphaseThe spindle fibres move chromosomes to the metaphase plate at the centre of the cell and hold them in position.
- TelophaseTelophase is the last stage of nuclear division in mitosis.
- CytokinesisCytokinesis begins during telophase.
- MeiosisMeiosis is a type of nuclear division that halves the number of chromosomes during the formation of gametes and recombines genetic material from…
- Homologous ChromosomesMany species such as humans maintain diploid cells but produce haploid gametes.
- The Stages of MeiosisGenetic recombination happens at the start of meiosis, making each chromatid different.
- Prophase 1During prophase 1, chromosomes supercoil and condense.
- Metaphase 1Homologous pairs of chromosomes assemble along the metaphase plate.
- Anaphase 1The homologous chromosomes are pulled by the shortening of the nuclear spindles to either pole centromeres first.
- Telophase 1Telophase 1 is the same as telophase in mitosis.
- Meiosis 2Meiosis 2 begins after a short interphase during which there is no DNA replication, only decondensation and synthesis of RNA and histones.
- Specialised Cells and TissuesMany organisms are multicellular, with cells that carry out different roles.
- Epithelial CellsEpithelial cells are adapted to cover internal and external body surfaces.
- Specialised Plant CellsSpecialised plant cells include palisade cells and guard cells in the leaves, root hair cells that help the plant absorb water and minerals from the…
- Organs and Organ SystemsAn organ is a collection of tissues adapted and working together to perform a particular function.
- Stem CellsStem cells are undifferentiated cells.
- Stem Cell PotencyTotipotent stem cells can differentiate into any type of cells.
- DifferentiationIn multicellular organisms unspecialised cells differentiate to become cells of many shapes, sizes and functions.
- Replacement of Red and White Blood CellsIn humans, the bone marrow contains haematopoetic stem cells which divide by mitosis and differentiate into a number of different types of blood…
- Sources of Animal Stem CellsThere are two sources of stem cells in animals: embryonic stem cells and adult stem cells.
- Sources of Plant Stem CellsPlant stem cells are present in the meristematic tissue (meristems) of plants.
- Uses of Stem CellsHeart disease - there has been some success in using stem cells to replace heart muscle tissue which has been damaged in a heart attack.
- EthicsBone marrow transplants have been successfully carried out for a number of years with little objection about the ethics of the procedure.
- Anaphase1.