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Homeostasis
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set of conditions under which living things can successfully survive
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Negative feedback/feedback inhibition
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turning itself off using the end product of the pathway.
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positive feedback
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further stimulates the pathway, for example more and more X is made
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G0
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temporarily nondividing until they get a signal to reenter the normal cell cycle.
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Interphase (G1, S, G2)
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not yet started to divide, regular activities
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S phase: replicates its genetic material, single chromosome in the nucleus is duplicated. sister chromatids held by centromere.
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G1 and G2: growth, performs metabolic reactions and produces organelles, proteins, and enzymes.
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These three phases are highly regulated by checkpoints and special proteins called cyclins and cyclin-dependent kinases (CDKs). To induce cell cycle progression, an inactive CDK binds a regulatory cyclin, the complex is activated, the cell cycle continues. To inhibit cell cycle progression, CDKs and cyclins are kept separate.
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losing control of the cell cycle, such as mutation in a protein, may cause cancer. Mutated genes that induce cancer are called oncogenes.
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Tumor suppressor genes produce proteins that prevent the conversion of normal cells into cancer cells, also can trigger apoptosis.
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Mitosis
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cell divides into two genetically identical daughter cells + maintaining the proper number of chromosomes from generation to generation
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1. Prophase: chromatin condenses
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2. Metaphase: chromosomes align in the middle.
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3. Anaphase: chromatids are pulled apart.
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4. Telophase: the cell completes splitting in two. cytokinesis：split along a cleavage furrow（animal)/ cell plate (plant)
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* Mitosis is involved in growth, repair, and asexual reproduction, so not happen in sex cell.
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plants do not have a nervous system but can produce several proteins found in animal nervous systems, such as certain neurotransmitter receptors.
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response to environmental stimuli, link environmental cues to biological processes, communicate with nearby plants.
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
