Cell Division-Cycle

• Cells aggregate to form the four basic tissue types: Connective tissues, Epithelium, Muscle, Nervous
• Organelles carry out the activities of life in the cell
• Nucleus - contains DNA, nuclear envelope, nuclear pores, nucleolus, nucleoplasm
• Cytoplasm - remainder of the cell between the nucleus and the cell membrane, cytosol
• Exosomes - vesicles that bud from one cell and merge with other cells
• Eukaryotic cell - has nucleus + organelles
• Somatic cell - have two copies of the genome and are diploid (2n)
• Stem cells - give rise to differentiated cells and to other stem cells (self-renewal)
• Basic functional unit of life
• Three domains of life: Archaea, Bacteria, Eukarya
• Prokaryotic cell - has no nucleus
• Germ cells - have one copy of the genome and are haploid (1n or n)
• Carbohydrates, lipids, proteins, and nucleic acids are the chemical constituents of cells
• There are two major stages of the cell cycle: interphase and mitosis.
• Interphase includes G1 phase, S phase, and G2 phase.
• Mitosis consists of four stages: prophase, metaphase, anaphase, and telophase.
• The cell cycle is controlled and regulated by checkpoints, including DNA damage checkpoints, apoptosis checkpoint, and spindle assembly checkpoint.
• Telomeres, which are chromosome tips, limit the number of cell divisions. Some cells have telomerase that keeps chromosome tips long.
• Kinases and cyclins activate genes for mitosis in cells.
• Apoptosis is a continuous process triggered by signals in the extracellular environment. It involves the activation of caspases to cut cell parts, wrapping them in membrane, and dismantling by phagocytes.
• Disruption of the balance between cell division and cell death can lead to cancer.
• Necrosis is a form of cell death associated with inflammation and damage.
• Meiosis is a type of cell division that forms gametes from germline cells. Gametes are haploid, while somatic cells are diploid.
• Meiosis I halves the chromosome number through synapsis, crossing over, and independent assortment.
• Meiosis II divides the cells from meiosis I, resulting in four haploid cells.
• Crossing over during prophase I and independent assortment during metaphase I generate genetic diversity.
• Endoplasmic Reticulum (ER) - rough ER (protein synthesis), smooth ER (lipid synthesis)
• Golgi apparatus - protein folding, sugar synthesis
• Vesicles - lipid-made, membrane-bound, saclike organelles for transport of substances within the cell
• Peroxisomes - sacs with enzymes for lipid breakdown and detoxification
• Lysosomes - membrane-bound sacs containing enzymes for degradation
• Mitochondrion - provides energy through breaking chemical bonds in food, contains ATP