4A Flashcards
what is the ultrastructure cell wall
-cell wall is made up of cellulose, which will allow more substances to pass through
- middle lamella is the first layer of cell wall which mostly made up of pectin that sticks cells together
- plasmodesmata is narrow threads of cytoplasm which connects cells
- pits are very thin region of the cell wall
what is the ultrastructure of chloroplast
- they have double membrane
- within chloroplast there are thylakoids that stack up to form grana, they are joined together by lamella
- cicular DNA of the chloroplast
what is the ultrastructure of amyloplast
- small, membrane bound organelle contains starch granule
what is the ultrastructure of tonoplast and vacuole
vacuole is a sac in plant cell surrounded by tonoplast, a mixture of enzymes, water, mineral and waste
what is the function of each organelle in plant cell
- cell wall: the cellulose component provides structural support
- plasmodesmata: allows cell communication
- middle lamella: provides stability to the plant by ensuring that adjacent plant cells are adhered together
- pits: allows transport of substances between cells
- chloroplast: site of photosynthesis - amyloplast: stores starch vacuole and tonoplast: keep the cell turgid, store various substances, break down and isolate unwanted chemicals and tonoplast controls substances that enter
what is the structure of starch
starch is a large that consists of two polysaccharides:
- amylose is unbranched helix-shaped chain with 1,4 glycosidic bonds between α glucose molecules
- amylopectin is a branched molecule, that has 1,4 and 1,6 between α-glucose molecules
what is the structure of cellulose
it consists of long chains of β-glucose joined together by1,4
glycosidic bonds, β-glucose molecules must be rotated 180° to each other in order to form the 1,4 glycosidic bonds, due to the inversion of β-glucose molecules many hydrogen bonds form between the long chains, giving cellulose it’s great strength
what is the function of starch
- its a storage polysaccharide because it is compact and insoluble which will prevent water to move into cells
what is the function of cellulose
- its the main structural component of cell wall due to its strength from the hydrogen bonds found between the chains of microfibrils, cellulose allows the plant to have high tensile strength and provides support to the plant
how do plant fibers have great strength
- the arrangement of cellulose microfibrils in a mesh-like pattern
- secondary thickening which results in a thick secondary cell wall and they can be exploited by humans in ropes and other materials
what are the three different tissues in the plant stem
- xylem, phloem and Sclerenchyma xylem and phloem are responsible for transporting various substances around the plant while sclerenchyma provide additional support to the plant
what is the structure and function of sclerenchyma
- they provide support and consist of bundles of dead cells which form long, hollow tubes, but they do have end walls present, they have lignin on cell wall but do not have pits, they more cellulose
what is the structure and function of xylem vessels
- they transport dissolved minerals and water also support
- their cell walls contain lignin which enables the vessel to withstand pressure
- xylem vessels form long hollow structure formed by dead cell
- there are regions that do not contain lignin known as pits and no end plates
what is the structure and function of phloem
- transport organic compounds up and down this is known as translocation
- phloem is made up of sieve tube elements which are the main conducting cells and companion and also include parenchyma, they also contain living cells
- companion cells control the metabolism
what does sustainability mean
refers to the use of resources in such a way that the requirments of the current generations and are met without depleting these resources for future generations, this requires renewable
