Cell Division, Cell Diversity and Cellular Organisation

• Mitosis


  Nuclear Division. The division of a cell to produce two genetically identical daughter cells
• Meiosis


  A type of cell division used to produce gametes that produce four genetically different haploid daughter cells from one parent cell
• Interphase


  The first stage of the cell cycle, during which the cell grows and replicated its DNA. The largest part of the cell cycle where cells grown and prepare for mitosis
• Cytokinesis


  The division of the cytoplasm at the end of mitosis
• Diploid


  Pairs of chromosomes (two/ a pair of each type)
• Haploid


  Not paired (half the number of chromosomes), cells with only one copy of each chromosome
• Chiasmata


  The points of contact between two non-sister chromatids
• Centromere


  The structure in the chromosome between the two chromatids
• Crossing over


  The exchange of DNA between paired homologous chromosomes
• Independent Assortment


  The production of different combinations of alleles in daughter cells due to the random alignment of homologous pairs along the equator of the cell during Metaphase 1
• Reductive Division


  Only half the number of chromosomes
• Homologous Pairs


  Pairs of chromosomes containing the same genes but different alleles
• Totipotent


  A type of stem cell which has the ability to differentiate into any type of cell in the body or in the placenta
• Pluripotent


  A type of stem cell which has the ability to differentiate into any cell type in the body
• Stem Cell


  A cell that can divide
• Apoptosis


  Programmed Cell death
• Acrosome


  An organelle found in the head of the sperm cells which is specialised to digest the outer coating of an egg cell during fertilisation
• Asexual Reproduction


  The production of genetically identical offspring from one parent through the process of mitosis
• Organ


  A group of specialised tissues working together to carry out a specific function
• Organ System


  A group of specialised organs working together to carry out a specific function
• S (synthesis) phase


  The second phase in the cell cycle where the DNA in the cell is replicated
• G1 checkpoint


  The first checkpoint in the cell cycle which occurs just before the end of G1 phase and commits the cell to division under favourable conditions
• G1 phase


  The first growth phase in interphase where the cell synthesises proteins and RNA, duplicates its organelles and increases in size before DNA replication in S phase
• G2 checkpoint


  The second checkpoint in the cell cycle which occurs at the end of G2 phase and checks that the DNA was correctly replicated during S phase before the cell enters mitosis
• G2 phase


  The second growth phase of interphase where the cell continues to increase in size and synthesize biomolecules
• Prophase


  The first stage in mitosis where the nuclear envelope breaks down, the centrosomes move to opposite poles of the cell, the mitotic spindle begins to form and the chromosomes condense
• Metaphase


  The second stage in mitosis where the chromosomes attach to the spindle fibres and align along the equator of the cell
• Anaphase


  The third stage in mitosis where the chromosomes are pulled apart to the poles of the cell
• Telophase


  The final stage of mitosis where new nuclear envelopes begin to form around the separated sets of chromosomes
• Prophase 1


  The first stage of meiosis where the nuclear envelope breaks down, the spindle fibres form and the chromosomes condense. Crossing over occurs
• Metaphase 1


  The second stage of meiosis where the homologous chromosomes line up along the equator of the cell. Independent assortment occurs
• Anaphase 1


  The third stage of meiosis where the chromatids are pulled apart to the poles of the cell
• Telophase 1


  The fourth stage of meiosis where the nuclear envelopes reform around the separated chromosomes
• Prophase 2


  The fifth stage of meiosis where the nuclear envelope breaks down, the spindle fibres form and the chromosomes condense
• Metaphase 2


  The sixth stage of meiosis where the chromosomes align along the equator of the cell
• Anaphase 2


  The seventh stage of meiosis where the chromatids are pulled apart to the poles of the cell
• Telophase 2


  The final stage in meiosis where the nuclear envelopes reform around the separated chromatids