* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Cell characteristics
Survey
Document related concepts
Cell growth wikipedia , lookup
Tissue engineering wikipedia , lookup
Cell culture wikipedia , lookup
Cytokinesis wikipedia , lookup
Cellular differentiation wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cell membrane wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cell nucleus wikipedia , lookup
Signal transduction wikipedia , lookup
Transcript
•Cells •Cells basic unit of live come from other living cells •Body is made of 75 trillion cells •260 types of cells •Cells are differentiated –specific characteristics Cells vary in size. • Ovary cell- 140 micrometers • Blood cell 7.5 micrometers • Cell shape is determined b y function Neuron (nerve cells) have long axons for transmitting impulses Skin cells are thin and flattened because they reproduce constantly Three main parts • Nucleus: Stores DNA – control cell functions • Cytoplasm- Made of cytosol and organelles • Cell membrane- Separates the cell from environment, protects and communicate cells Made of a double layer of phospholipids It is the boundary of cell and perform some functions: • Communication among cells • Protect cell from the outside environment • Selectively Permeable- Allow s substances in and out of cell. • It allows receive messages from other cellssignal transduction - It is mainly composed of lipids and proteins, and some carbohydrates It is a double layer of phospholipids. • The phospholipids head is hydrophilic ( loves water) which are in the outside of the membrane and the tails are hydrophobic ( afraid of water) located inside of the membrane Interior is oily because made of fatty acids. - • Carbon dioxide, oxygen and steroid can pass through membrane easily. • The layer is impermeable to water molecules: proteins, amino acids… • Cholesterol molecules embedded in cell membrane make cell impermeable to some of these molecules and stabilize it. - Contains a few lipids but many proteins Proteins in the plasma membrane decide the functions of the membrane. Proteins are classified by shape, location and function within the phospholipids bilayer. Some are embedded in the plasma membrane and are compact and globular. They function as channels for small ions and molecules. Some proteins coil in the plasma membrane and extend outward, they function as receptors. Peripheral proteins are globular and function as enzymes and parts of signal transduction pathways. Other Peripheral proteins are cellular adhesion molecules that enable certain cells to bind. Carbohydrate groups associate with peripheral proteins form glycoproteins that help cells to recognize each other. This is important because cells group together to form tissues. Some cells are separated by intercalated spaces with fluid between. Other cells are tightly packed with structures called intercellular junctions that connect their cell membranes. Types of intercellular junctions: • Tight junction: area of fusion, surrounds cells like a belt. Example: digestive tract. • Desmosomes: adjacent skin cells, they reinforce structural unit. Example : skin cells. • Gap junctions: channels that allow ions to move between them. Example: heart. • Proteins called Cellular Adhesion Molecules (CAMs)guide cells to move. Example : white blood cells 1. Cytoskeleton 2. Endoplasmic Reticulum 3. Ribosomes 4. Golgi Apparatus 5. Mitochondria 6. Lysosomes 7. Peroxisomes 8. Centrosomes 9. Cilia and Flagella 10. Microfilaments an d tubules 11. Nucleus It is a group of protein rods and tubules that form a supportive system. Made of membraned-bound flattened sacs, elongated canals and fluid filled vesicles. It is widely distributed through the cytoplasm, and communicate with other organelles Function: Synthesis of protein and lipid molecules The outer membrane of ER is full of spherical, tiny structures called ribosomes. This is the appearance of Rough Endoplasmic Reticulum. The tubules of Endoplasmic Reticulum move to Golgi apparatus for further processing. Smooth Endoplasmic Reticulum lacks of ribosomes. It contains enzymes important in lipid synthesis. Smooth Endoplasmic Reticulum is found in cells in the digestive tract and it is important in the breakdown of drugs and alcohol. Some are found in Endoplasmic Reticulum and others are free in the cytoplasm. All ribosomes are composed of RNA and create a supportive enzyme activity for amino acids to form proteins. Ribosomes are the sites of protein synthesis. Composed of a tack of half a dozen of flattened membranous sacs called cisternae. The Golgi apparatus refines, packs and delivers protein synthesis. Proteins arrive at the Golgi apparatus enclosed in tiny vessicles from the Endoplasmic Reticulum and fuse with the innermost of the apparatus to receive proteins. As the glycoproteins pass from layer to layer through the Golgi stacks, they are modified chemically. The vessicles fuse and they are release outside (exocytosis) Movement of substances within cells by the way of vessicles is called vessicle trafficing. It is formed by elongated, fluid filled sacks about 2-5 micrometers. Contains a small amount of DNA that encodes information for making new kinds of proteins and specialized RNA. A mitochondrion has two layers : an outer membrane and an inner membrane The inner membrane is folded in to form of shelflike partitions called Cristae. Small enzymes are connected to cristae. The mitochondrion captures and releases energy into special chemical bonds of the molecule ATP. ( Adenosine Triphosphate) A typical cell contains about 1700 of them They are called garbage disposals They posses powerful enzymes that destroy bacteria. Human lysosomes contain 40 types of enzymes. Membranous sacks that resemble lysosomes in size and shape Most abundant in liver and kidneys Contain enzymes –peroxidases Functions: Breakdown lipids, bile acids, degrade chemicals and detoxifies alcohol It is located in the cytoplasm near the nucleus Consist in two hollow centrioles. During cell division, the centrioles move away from each side of nucleus. Motile extensions of cells They are structurally different and they differ in length and number present. Cilia are abundant on the free surface of certain epithelial cells. A cell usually only have one flagella, wavelike movement. - Threadlike structures Microfilaments are tiny protein rods. They cause movement, like in muscle fibers. Microtubules are long and slender, composed of protein tubulin, and help to maintain the rigid of the cell It is usually large, spherical and contains the genetic material (DNA) The DNA occurs as extremely long molecules complexed with proteins form chromatin fibers, which are visible in a microscope as chromosomes. The nucleus is double layered in a nucleus envelope, which contain pores. The nucleus pores are channels with different proteins. Nucleus contains a fluid (nucleoplasm) Nucleolus is inside nucleus and is a small dense body composed of DNA. It is the site of ribosomes production Chromatin is inside the nucleus and contain loosely coiled fibers in the nuclear fluid. Chromatin means colored When cell division begins , these fibers form chromosomes. Chromatin fibers contain DNA wrapped around proteins called histones.