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Cellular Reproduction. How Do Cells Receive Nutrients?. Cell Membrane The membrane allows in: Food Water Oxygen. The Cell Membrane. Selectively permeable – allows only certain materials to pass through.
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How Do Cells Receive Nutrients? • Cell Membrane • The membrane allows in: • Food • Water • Oxygen
The Cell Membrane • Selectively permeable – allows only certain materials to pass through. • Diffusion – the movement of molecules from areas of higher concentration to areas of lower concentration • Osmosis – the movement of molecules from areas of higher to areas of lower concentration through the cell membrane.
The Cell Membrane • Three types of solution • Hypotonic • Note: = Water = Concentration
The Cell Membrane • Three types of solution • Isotonic • Note: = Water = Concentration
The Cell Membrane • Three types of solution • Hypertonic • Note: = Water = Concentration
The Cell Membrane • Three types of solutions • Hypotonic Isotonic Hypertonic • The concentration of water outside of the cell is: • Higher Same Lower
The Cell Membrane • Three types of solutions • Hypotonic Isotonic Hypertonic • The concentration of dissolved substance outside of the cell is: • Lower Same Higher
The Cell Membrane • Three types of solutions • Hypotonic Isotonic Hypertonic • The cell contents will: • Swell Stay the same Shrink
The Cell Membrane • The concentration (amount) of dissolved substance affects the movement of water into and out of the cell.
The Cell Membrane • Homeostasis – the ability of an organism to maintain a constant internal balance even when the conditions around it change. • Examples: • Turgor Pressure – the force of the cell contents pushing against the cell wall
The Cell Membrane • Passive Transport – the movement of substances through the cell membrane without using energy. • Active transport – the movement of molecules from areas of lower to higher concentration with the use of energy.
The Cell Membrane • Protein Molecules Lipid Molecules
Surface Area to Volume Ratio • Cell Diameter increases 10 times • Surface Area increases 100 times • Volume increases 1000 times
Surface Area to Volume Ratio • Double the cell size (2 times) • 8 times more nutrients required • 8 times more waste to excrete • Surface area increase only 4 times • Cell starve to death or be poisoned
Why is it important to have many small cells rather than one Larger cell? • Larger cell has: • Difficulty in receiving enough nutrients and oxygen • Difficulty in removing wastes • One copy of DNA
Cell Division Cell divides into two daughter cells
Mitosis • Process by which the nucleus of the cell is divided into two nuclei, each with the same number and kinds of chromosomes as the parent cell.
Interphase • G1 phase • Cellular Growth • Development • S phase • DNA Replication • Protein synthesis • G2 phase • Synthesis of organelles • Materials for cell division
Chromosomes • Contain the genetic information (DNA) that is passed from one generation of cells to the next.
Chromosomes • DNA • Proteins (histones)
Chromosome Structure Sister Chromatid Centromere DNA
Prophase Longest (50 - 60%) • Appearance of chromosomes • Nucleolus disappears • Nuclear membrane breaks down • Centrioles separate and migrate to opposite poles of cell • Spindle fibers from the centrioles attach to the centromeres • Chromatin coils up (shortens) into chromosomes
Metaphase • Chromosomes line up across center (equator) of cell • Spindle fibers from centromere to centrioles Shortest
Metaphase Chromosome Centriole Spindle Fiber
Anaphase • Sister Chromatids split at Centromere • Individual Chromosomes move toward poles • Chromatid pairs from each chromosome separate from each other • Chromatids are pulled apart by the shortening of the microtubules in the spindle fibers
Telophase Final Phase • Spindle fibers breakdown • Chromosomes uncoil into Chromatin • Nuclear envelope (membrane) reforms • Nucleolus becomes visible • Chromosome reach the ends of the cell • The centrioles double • The cytoplasm is divided
Cytokinesis • The process by which the cytoplasm divides, forming two new cells.
Cytokinesis • Animals • Cell membrane • pinches inward • Plants • Cell plate
Result of Mitosis Two cells that are identical to each other.
Cell Theory • Developed by Robert Hooke • Came up with the name cells • Encouraged other scientists to look for cells in their research • Cell theory is made up of three main ideas:
Cell Theory • All organisms are composed of one or more cells. • Most organisms are multicellular • Cells are the basic units of structure and function in organisms • All cell arise from existing cells • Cell theory states that a cell divides to form two identical cells