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CELL structure & function. The cell theory is a fundamental concept in biology. It states: All living things are composed of cells. The cell is the basic structural unit of all living things. All cells arise from pre-existing cells. CELL THEORY . PROKARYOTIC Lack a “true” nucleus
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The cell theory is a fundamental concept in biology. It states: • All living things are composed of cells. • The cell is the basic structural unit of all living things. • All cells arise from pre-existing cells. CELL THEORY
PROKARYOTIC • Lack a “true” nucleus • Do not have organelles • Bacteria is the most common example • EUKARYOTIC • Have a nucleus • Contain organelles separated by membranes • Much larger than prokaryotic cells Two types of cells
Two Types of Eukaryotic Cells Animal Cells Plant Cells
1. CELL MEMBRANE • The “skin” of the cell; it holds everything inside. • It is SEMIPERMEABLE which means it allows certain things to go through it. 2. NUCLEUS • The “control centre” or “brain” of the cell. • Usually the largest organelle. • Where DNA is stored. DNA contains the chromosomes which is where all genetic information is found. COMMON ORGANELLES
3. CYTOPLASM • A “jelly-like” substance composed of mostly water that surrounds and protects the organelles. 4. VACUOLES • “Sac-like” containers made from pieces of cells membrane.
5. RIBOSOMES • The “builders” of protein. • They are dark looking dense granules that can be free floating in the cytoplasm or attached to the endoplasmic reticulum. • Composed of RNA and PROTEIN. 6. ENDOPLASMIC RETICULUM • A series of “canals” or small tubules that branch out from the nucleus. • ROUGH ER has ribosomes attached. • SMOOTH ER has no ribosomes.
7. GOLGI APPARATUS • Looks like a flattened stack of pancakes. • Where protein is stored until needed. • If the protein is needed outside of the cell, the GA packages it into a vacuole and sends it to the cells membrane for transport. 8. MITOCHONDRIA • The “powerhouse” of the cell. • The site of CELLULAR RESPIRATION in cells which use glucose and oxygen to make carbon dioxide, water and ATP (energy).
9. LYSOSOMES • Membrane bound sacs that aid in digestion. • Certain types of human white blood cells use lysosomes to destroy invading bacteria. For this reason they have the nickname “SUICIDE CELLS”. • They also function in breaking down damaged organelles in a cell.
Despite the fact that plant and animal cells contain the above 9 organelles in common they have some significant difference as well. DIFFERENCES
CELL WALL • Made from a rigid material called CELLULOSE. • They provide plants with structural support and allow them to grow tall without falling over. • CHLOROPLASTS • These organelles capture energy from the sun and convert it into chemical energy in a process called PHOTOSYNTHESIS. • They are composed of a double membrane and an internal membrane system that contains CHLOROPHYLL which is a light capturing molecule.
CENTRIOLES • Centrioles organize the spindle apparatus on which the chromosomes move during mitosis. • They are critical to cell division.