Mitosis and meiosis Flashcards
2 types of cells
Somatic cells
Germ cells
Function of mitosis
Grow and repair tissues
How many stages during mitosis?
4 actives stages followed by interphase:
Prophase, Metaphase, Anaphase and Telophase
Prophase
Nuclear membrane breaks down
Chromosomes condense
Chromosomes still together and are called the chromatids (held by centromere)
Centrioles at either end of cell + spindle starts to form
Metaphase
Chromosomes line up in middle of cell
Chromatids draw apart at centromere
Anaphase
Chromosomes attach to spindle fibres and chromatids pull apart on opposite site poles of cell
Telophase
Spindle fibres break down
Nuclear membrane reforms on each side
Cell starts to constrict in middle until divided in 2
Each new daughter cell is identical
Cytokinesis
Splits the cytoplasm
What happens during meiosis?
Germ cells divide (ovary and testis)
Each daughter cells has half of the information of the mother cell
Phases of meiosis
Interphase as resting phase
Prophase I, Metaphase I, Anaphase I, Telophase I
Prophase II, Metaphase II, Anaphase II, Telophase II
Prophase I
Homologous chromosomes lie side by side & duplicate
Joined by centromere
Crossing over of chromosomes - influence on characteristics
Metaphase I
Homologous chromosomes lie along line of equator
Fibrous spindle starts to form
Anaphase I
Pairs separate
Chromatids migrate along spindle fibres towards poles of cell
Telophase I
Cytoplasm begins to divide
Nuclear membrane does not reform
Prophase II
Transitory phase - no need to replicate chromosomes
