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unit 1 bio revision - Coggle Diagram

- - - - Plant cells
      - Animal cells
      - Eukaryote
      - Organelles
        
        cytoskeleton
        
        nucleus
        
        nucleolus
        
        rough ER
        
        smooth ER
        
        ribosomes
        
        golgi body/ apparatus
        
        mitochondria
        
        cytoplasm
        
        plasma membrane
        
        the plasma membrane is the semi-permeable outer layer of a cell
        
        formation
        
        phospholipids
        
        phospholipids are the primary structure of the plasma membrane.
        
        phospholipids have a non polar, hydrophobic tail and a polar head that is hydrophilic
        
        lysosome
        
        centriole
        
        cilium
        
        flagellum
        
        peroxisome
        
        vacuole
        
        chlorophyll
        
        chloroplasts
        
        DNA/genes
        
        microtubule
  - - - Interphase
        
        Interphase takes up majority of the cell cycle. Involves 3 stages
        
        G1 (growth 1)
        
        First stage of the cell cycle after cytokinesis
        
        Includes the creation of new organelles, cytosol and proteins
        
        G2 (growth 2)
        
        Last stage of interphase
        
        Further growth to the cell and more protein synthesis. Cell should have doubled in size by the end of G2
        
        S (synthesis)
        
        Second stage of interphase
        
        Cell replicates it's DNA
        
        Checkpoints
        
        Checkpoints check for the size, nutrients, growth factors, DNA damage and DNA replication during interphase
        
        First checkpoint
        
        During G1
        
        Checks for damage to the DNA before replication, as well as cell size, nutrients and growth factors
        
        Second checkpoint
        
        During G2
        
        Before mitosis begins, the DNA and size of cell is checked
        
        G0 phase
        
        G0 phase is a phase in the cells life where growth is paused and cell does not enter mitosis. It may be temporary or permenant
        
        A cell will enter G0 phase if damage is detected during checkpoints.
      - Mitosis
        
        Mitosis is the stage in the cell cycle where a cell splits into two daughter cells. There is 5 stages.
        
        Prophase
        
        First stage of mitosis
        
        Chromosomes condense, nuclear membrane starts to break down, centrioles begin to move apart, spindles begin to form and attach to chromosomes.
        
        Metaphase
        
        Second stage of mitosis
        
        Chromosomes begin to line up along the middle of the cell, centrioles are at opposite ends of the cell
        
        Anaphase
        
        Third phase of mitosis
        
        Chromosomes are pulled apart by spindles shortening. They are split into two chromatids
        
        Cytokinesis
        
        Last stage of mitosis
        
        The cell is split into two daughter cells. In animal cells, a contracting ring of microfilaments squeezes the cell in two, in plant cells a cell plate from between the groups and creates a new cell wall
        
        Telophase
        
        Fourth phase of mitosis
        
        Nuclear membranes begin to form around the two groups of chromosomes/chromatids, chromosomes begin to condense, and spindles begin to dissolve
      - Cell Death
        
        Apoptosis
        
        Programmed cell death that occurs if a cell is damaged, infected or old.
        
        Initiated by one of two pathways
        
        Intrinsic pathway (aka mitochondrial pathway)
        
        Internal components are damaged > Specific proteins activate mitochondrial pathway > mitochondria release cytochrome c into cytosol > begins a cascade that results in caspace enzyme activation
        
        Extrinsic pathway (aka death receptor pathway)
        
        Extracellular (outside the cell) signals are recognised by death receptor cells on the cell membrane > cascade begins which results in caspase enzyme release
        
        Execution
        
        After apoptosis is initiated, caspase enzymes are activated in the cell and travel around the cell digesting proteins > cascade of reactions result in digestion of organelles and cell contents > cell and nucleus shrink and membrane warps because of cytoskeleton breakage/digestion > membrane detaches from cell and forms apoptotic bodies > chemicals are released that attract phagocytes, which consume the apoptotic bodies
        
        Malfunctions in apoptosis
        
        Malfunctions in apoptosis can result in disease.
        
        Too much apoptosis can lead to diseases like alzheimers
        
        Too little apoptosis can result in unwanted growths and mutated cells
        
        Necrosis
        
        Cell death caused by disease or injury to the cell
      - Cell Cycle controls
        
        Contact inhibition
        
        Stops cells from growing and replicating when the cell is surounded/ crowded
        
        Without contact inhibition, cells can replicate uncontrollably and form unwanted growths
        
        Mitogens
        
        Mitogens are peptides or small proteins that induce a cell to begin cell division eg. Hormones
        
        Telomeres
        
        Repetitive nucleotide sequences at the end of each chromosome. They shorten each time a cell divides and once the telomeres have reached the end, the cell will stop dividing.
        
        Genes
        
        Proto-onco genes
        
        Regulate processes such as cell division and apoptosis. If mutated, they can become oncogenes, which cause cancer.
        
        Tumor Suppressor genes
        
        Suppress tumor growth and make sure growth is in control, and promotes apoptosis. Mutated tumor suppressor genes mean your more more likely to get cancer, and the mutation can be passed down.
    - - Binary fission
        
        How prokaryotic cells replicate
        
        Can happen in 20 minutes if conditions are suitable
        
        The cell replicates its DNA > The plasma membrane grows inwards, dividing the cell in two > the cell was reforms > results in two identical cells