The cell Dr.Ola Tork
Introduction The smallest functional unit of the body. Grouped together to form tissues, each of which has a specialized function e.g. blood, muscle, bone… Different tissues are grouped together to form organs e.g heart, stomach, brain …… Organs are grouped together to form systems,e.g. digestive system, respiratory system
The Cell Structure and function A cell consists of plasma membrane inside which a number of organells in a watery fluid called cytoplasm They are: 1. Nucleus 2. Mitochondria 3. Ribosomes 4. Endoplasmic reticulum 5. Golgi appararus 6. Lysosomes 7. Cytoskeleton
1 Nucleus 2 Nuclear pore NucleusNuclear pore 3 Rough endoplasmic reticulum (RER) 4 Smooth endoplasmic reticulum (SER) 5 Ribosome on the rough ER Ribosome 6 Proteins that are transported Proteins 7 Transport vesicle vesicle 8 Golgi apparatus Golgi apparatus 9 Cis face of the Golgi apparatus 10 Trans face of the Golgi apparatus 11 Cisternae of the Golgi apparatus
Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. Numerous circular vesicles can be seen in proximity to the organelle
Plasma membrane Two layers of phospholipids with protein and sugar molecules embedded in them Phospholipid molecules have a head and tail The head is electrically charged ( hydrophilic) The tail is not charged ( hydrophobic) The phospholipid layer is arranged like a sandwich The heads aligned on the outer surface. The tails form the central layer
The membrane proteins functions Immunological identity ( branched carbohydrate chain) Specific Receptors for hormones Enzymes Transport across the membrane
Nucleus In every cell in the body, Except ? No. ? It is the largest organelle It contains the body genetic material Functions: 1. Direct all metabolic activities of the cell 2. Control reproduction of the cell
Mitochondia Sausage- shaped Power house Involved in aerobic respiration Synthesis of ATP No of mitochondria ?
Ribosomes Tiny granules Composed of RNA and proteins Synthesis of proteins Free ribosomes
Endoplasmic reticulum Series of interconnecting membranous canals In the cytoplasm Types: 1. Smooth ER : synthesizes lipids and steroid hormones 2. Rough ER: synthesizes proteins which are exported out side from cells
Golgi apparatus Stacks of closely folde flattened membranous sacs It is larger in cells that synthesize and export proteins Package proteins into membrane bound vesicles (secretory granules).
Lysosomes It is a type of secretory granules Breaking down fragments of organells and large molecules inside the cells In WBC they digest microbs
Cytoskeleton Types: 1. Microfilaments 2. Microtubules 3. Centrosome 4. Cell extensions
Microfilaments Smallest fibers Functions: 1. Provide support 2. Maintain shape of the cell 3. Permit contraction ( muscle cells)
Microtubules larger contractile proteins Involved in movement of : 1. Organelles within the cell 2. Chromosomes during cell devision 3. Cell extensions
Centrosome Direct organisation of microtubules within the cell Consists of a pair of centrioles Play important role during cell division
Cell extensions They project from plasma membrane Consists of microtubules Types: 1. Cilia: small hair –like 2. Flagella: single long whip –like projection