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level: The cell cycle and Mitosis

Questions and Answers List

level questions: The cell cycle and Mitosis

QuestionAnswer
Define cell cycleThe process that all body cells in multicellular organisms use to grow and divide
Explain the cell cycle processInterphase, subdivided into 3 growth stages: - gap phase 1 (G1) = cell grows and new organelles and proteins are made - synthesis (S) = cell replicates its DNA ready to divide by mitosis - gap phase 2 (G2) = cell keeps growing and proteins needed for cell division are made - M phase = mitosis and cytokinesis
How is the cell cycle regulated- G1 checkpoint = the cell checks that the chemicals needed for the replication are present and for any damage to the DNA before entering the S-phase - G2 checkpoint = the cell checks whether all the DNA has been replicated without and damage. If it has, the cell can't enter mitosis -Metaphase checkpoint = the cell checks that all the chromosomes are attached to the spindle before mitosis can continue
What are the main stages of mitosisInterphase, prophase, metaphase, anaphase and telophase
Describe interphase- Cell carries out normal function, but also prepares to divide. - The cell's DNA is unravelled and replicated, to double it's genetic content - organelles also replicate - ATP content increases
Describe prophase- chromosomes condense - tiny bundles of protein called centrioles start moving to opposite ends of the cell, forming a network of protein fibres across it called the spindle - the nuclear envelope breaks down and chromosomes lie free in the cytoplasm
Describe metaphase- the chromosomes line up along the equator of the cell and become attached to the spindle by their centromere - at the metaphase checkpoint, the cell checks that all the chromosomes are attached to the spindle before mitosis can continue
Describe anaphase- the centromeres divide, separating each pair of sister chromatid - the spindles contract, pulling chromatids to opposite poles of the cell
Describe telophase- the chromatids reach the opposite poles of the spindle - they uncoil and become long and thin and are called chromosomes again - a nucleus envelope forms around each group of chromosomes, so there are now 2 nuclei - 2 genetically identical cells are produced