[Music] hi and welcome back to three science lessons Cole you K by the end of this video you should be able to describe how you tear cells xylem cells and phloem cells are specialized to carry out their functions and these are all examples of plant cells in the last video we saw that cells can become specialized in other words they develop adaptations which have them to carry out the particular function when cells become specialized scientists call that process differentiation in this video we're looking at specialized plant cells we've already seen the structure of a general plant cell remember that three of the key structures on the plant cell are the chloroplasts the cellulose cell wall and the permanent vacuole so the first specialized plants are going to look at our cold and root hair cells I'm showing you a picture here of a root as you can see the roots covered with hairs these hairs increase the surface area of the root so it can absorb water and dissolve mint was more effectively now these has a formed on root hair cells and I'm showing you a drawing of a moon hair cell here so the first key feature of the root hair cell is the root hair but as we said these increase the surface area of the root the second key feature is that lute hair cells do not contain chloroplasts remember that chloroplasts contain chlorophyll and they're the sites of photosynthesis now photosynthesis requires energy from light Lootera cells cannot carry out photosynthesis because they're underground so they've got no need for chloroplasts okay ii plants are going to look at our xylem cells i'm showing you a drawing of xylem cells here now xylem are found in the plant stem and they form long tubes these tubes carry water and dissolved minerals from the roots of the plant to the leaves the first key point about xylem cells is that they've got very thick walls containing a chemical called lignin now this provides support to the plant however because the cell walls are sealed with lignin this actually causes the xylem cells to die the second thing to notice is that the end walls between the cells have completely broken down this means that the cells now form a long tube so water and dissolved minerals can flow easily xylem cells have got no nucleus cytoplasm vacuole or chloroplasts in fact sign themselves have got no internal structures at all again that makes it easier for water and minerals to flow okay the final plants are going to look out off phloem I'm showing you the structure of phloem cells here phloem tube's car we dissolved sugars up and down the plant now the first important point is at phloem consists of two different types of cells the first type are called phloem vessel cells these cells have no nucleus and only limited cytoplasm the end walls of the vessel cells have pores called sieve plates now both of these features allow dissolved sugars to move through the cell interior because phloem vessels cells have got very limited cytoplasm they haven't got many mitochondria so each flow vessel cell has a companion cell connected by claws mitochondria and the companion cell provide energy to the phloem vessel cell remember your fun plenty of questions on specialized plant cells in my vision workbook and you can get that by clicking on the link above okay so hopefully now you should be able to describe how loot hair cells xylem cells and phloem cells are specialized to carry out their functions [Music]