Download Protoplast >composed of cell`s nucleus and surrounding

Protoplast
>composed of cell's nucleus and surrounding protoplasmic materials
>can be made by degrading cell walls with a mixture of the appropriate polysaccharidedegrading enzymes
> isotonic solution to prevent rupture of the plasma membrane.
Cytoplasm
>contains cytosol and the organelles
>complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills
much of the volume of a cell
>jelly-like material outside the nucleus
>most cellular activities occur|metabolic pathways
Nucleus
>spherical body containing many organelles, including nucleolus
>highly specialized
>multi-functional
>contains DNA
>surrounded by nuclear envelope
>separates contents of nucleus from cellular cytoplasm
>double-layered membrane
>has nuclear pores
>allows specific types and sizes of molecules to pass back and forth
between the nucleus and cytoplasm
>has protein lining called nuclear lamina
>binds to chromatin and other nuclear components
>disintegrates but reforms as the two cells complete their formation in mitosis
>contains nucleolus
>membrane-less organelle within the nucleus
>manufactures ribosomes
>contains ribosomes
>cell's protein-producing structures
functions:
>controls many functions of the cell|metabolic functions
>stores hereditary material
Plastids
>major organelles foind in cells of plants and algae
>manufacture and storage of important chemical compounds of the cell
>contains pigments used in photosynthesis
>responsible for photosynthesis
>present in meristematic regions of the plant
>chloroplast
>green plastids
>elongated or disc-shaped organelle containing chlorophyll
>enclosed in a double membrane called intermembrane space
>contains stroma
>semi-fluid material
>material inside chloroplasts
>contains one or more molecules of small circular DNA
>also contain ribosomes; however most of its proteins are encoded by
genes contained in the host cell nucleus
>contains thylakoid
>sub-organelle
>site of photosynthesis
>arranged in stacks called granum
>lumen
>each 0.01 μm thick.
>chromoplasts
>colored plastids
>for pigment and storage
>red, yellow or orange in colour and are found in petals of flowers and in fruit
> colour is due to two pigments, carotene and xanthophyll
>yellow-to-red colored chromoplasts manufacture carotenoids
function:
>attract agents of pollination
>attract agents of dispersal
>gerontoplasts
>control the dismantling of the photosynthetic apparatus during senescence
>leucoplast
>occur in plant cells not exposed to light
>colorless due to the absence of pigments
>colorless plastids
>involved in synthesis of starch, oils, and proteins
>amyloplast-starch storage and detecting gravity
>elaioplasts- storing fat
>proteinoiplast/aleuronoplast- storing and modifying protein
functions:
>different function for different kind of plastid
Mitochondrion
>spherical to rod-shaped organelles with a double membrane
>sizes range between 1 and 10 micrometers in length
>pccur in numbers that directly correlate with the cell's level of metabolic activity
>two specialized membranes encircle each mitochondrion present
>intermembrane space
>internal matrix
>outer membrane contains many channels formed by porin
>acts like a sieve
>inner membrane is infolded many times - cristae
>walls are the site of the cell's energy production
>more selective than outer membrane
functions:
>converts the energy stored in glucose into ATP for the cell
Cell wall
>Plant cell walls vary from 1/10 to several µm thick
>tough, flexible, rigid layer that surrounds some types of cells
>located outside the cell membrane
>composed of cellulose, hemicellulose, pectin
>cellulose microfibrils are linked via hemicellulosic tethers to form the cellulosehemicellulose network, which is embedded in the pectin matrix.
>xyloglucan-most common hemicellulose in the primary cell wall
>three layers:
>middle lamella
>rich in pectins
>consists of a complex set of polysaccharides
>important cell wall polysaccharide that allows primary cell wall
extension and plant growth
>broken down by pectinase and pectinesterase in ripening
>fruit becomes softer as the middle lamellae break down and
cells become separated from each other
>water soluble
>sticky
>used in food as gelling agent, specially in jams and jellies
>outermost layer
>contains magnesium, calcium pectates
>forms the interface between adjacent plant cells and glues them
together
>primary cell wall
>thin, flexible, extensible layer formed while the cell is growing
>secondary cell wall
>thick layer formed inside primary cell wall
>not found in all cell types
>contains lignin
>strengthens and waterproofs the wall
>derived from wood
>fills the spaces in the cell wall between cellulose,
hemicellulose, and pectin
>plays crucial part in conducting water in plant stems
>hydrophobic
>present in all vascular plants but not in bryophytes
>primary walls extend by acid growth.
>contains enzymes
>cork cells in the bark of trees are impregnated with suberin; forms the permeability barrier in
primary roots
>secondary walls may contain microscopic silica cyrstals
formation
>middle lamella is laid down first, formed from the cell plate during cytokinesis
>primary cell wall is deposited inside the middle lamella
>microfibrils are held together by hydrogen bonds; tensile strength
functions:
>protects cell from foreign objects
>takes in nutrients for the cell
>determines shape, strength
>support
>controls turgor pressure
>serves as a passage for substances
>signaling
>filters out large molecules but allows smaller proteins and nutrients(< 30 – 60 kDa) to
enter.
>acts as a pressure vessel, preventing over-expansion when water enters the cell
Vacoule
>water-filled shit
>membrane-bound organelle
>formed by fusion of multiple membrane vesicles
>no basic shape
>occupies 30-80% of cell's volume
>developing cells in meristems contain small provacoules
>cells of vascular cambium have many small vacuoles in the winter and one large one in the
summer.
>most plants store chemicals in vacuole that reacts with chemicals in cytosol
>if cell is broken, two chemicals react forming toxic chemicals
>surrounded by tonoplast
>controls movement of molecules between cytosol and sap
>separates vacoular content from cell's cytoplasm
>regulates movements of ions around the cell
>contains aquaporins
>control flow of water into and out of vacuole
functions:
>isolate materials that might be harmful to the cell
>waste products
>water in plant cells
>maintain internal hydrostatic pressure or turgor within cell
>maintain pH
>support structures such as leaves and flowers due to the pressure of central vacoule
>seeds: stored proteins are kept in "protein bodies"--modified vacoules
>helps maintain cell shape