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THE CELL AND CELLULAR ENVRIONMENT Cell Basic structural unit of all plants and animals A membrane enclosing a thick fluid and a nucleus Specialized to carry out all the body’s basic functions Procaryot Single-cell organism Bacteria Structures Cell membrane Cytoplasmic matrix Nucleoid Cell wall Cell Membrane Absolute requirement for all living organisms Cells must interact in a selective fashion with their enviornment Cells must acquire nutrients, eliminate waste and maintain their internal environment based on external changes Encompasses the cytoplasm Cytoplasmic matrix Lacks organelles Subtance that lies between the plasma membrane and the nuceloid Largely water about 70% of bacterial mass is water Often packed with ribosomes made of protein and RNA protein synthesis {building of proteins} The nucleoid Where the DNA is located DNA is a single circle, double stranded Composed of 60% DNA, some RNA and a small amount of protein Cell Wall One of the most important parts of the procaryotic cell Gives shape Protects from osmotic lysis lysis; breaking down of a cell osmosis; movement of water Functions of Procaryotic Structures Plasma Membrane selectively permeable barrier mechanical boundary nutrient and waste transport location of many metabolic processes detection of cues for chemotaxis Chemotaxis Directed movements according to chemicals in their enviornment Finding of food Gas vacuole buoyancy Ribosomes protein synthesis Periplasmic space nutrient processing and uptake Cell wall shape protection from lysis Capsules and slime layers resistance to phagocytosis adherence to surfaces Phagocytosis Processing of engulfing or eating such as the immune system consuming or destroying pathogens Fimbriae and pili attachement to surfaces mating Flagella movement Endospore survival under harsh environmental conditions The Cell ..\Illustrations\cell.gif Eucaryotic Cell Structure Multi-cell organisms Structures, characteristics and functions Cytoplasmic Matrix Endoplasmic Reticulum Golgi Apparatus Lysosomes and endocytosis Ribosomes Mitochondria Chloroplasts Nucleus and cell division External cell coverings Cilia and flagella Eucaryotic cells contain organelles Organelle intracellular structures that perform specific functions Cytoplasmic matrix Featureless, homogenous substance One of the most important and complex parts of the cell The environment of the organelles Location of many important biochemical processes Several physical changes are due to matrix functions Several physical changes are due to matrix activity Water A eucaryotic cell is 70 to 85% water by weight Two forms bulk or free water bound water or water of hydration Bulk or free water Osmotically active water Bound water Bound to the surface of proteins Where water, nutrients and waste products can be stored Microfilaments Structure Movements Form the cytoskeleton Contain structures such as flagella, cilia and lamellipodia. Plays important roles in transport and division. Lamellipodia Propels the cell across a substrate Endoplasmic Reticulum Transport of materials Protein and lipid synthesis Golgi Apparatus Packaging and secretions of materials for use within the cell Lysosome formation Lysosomes Intracellular digestion Cells need to make proteins. Those proteins might be used as enzymes or as support for other cell functions. When you need to make proteins, you look for ribosomes. Ribosomes are the protein builders or the protein synthesizers of the cell. They are like construction guys who connect one amino acid at a time and build long chains. Ribosomes are found in many places around the cell. You might find them floating in the cytoplasm (cytosol). Those floating ribosomes make proteins that will be used inside of the cell. Other ribosomes are found on the endoplasmic reticulum. Endoplasmic reticulum with attached ribosomes is called rough. It looks bumpy under a microscope. Those attached ribosomes make proteins that will be used inside the cell and proteins made for export out of the cell. Intracellular digestion Breaking down of large molecules into smaller ones Mitochondria “powerhouse” of the cell Energy production Chloroplasts Photosynthesis Nucleus Ribosomal RNA synthesis Ribosome construction