Transcript Organelles In Plant Cell

Organelles
In Plant Cell
PLANT CELL STRUCTURE
Cell Wall
-a layer which only found in plant
-a dead layer
-the outermost layer of plant cell,
make up by cellulose which
forms very thin fibers
-strong and rigid
-gives shape to the cell
-protects and supports the
enclosed substances
(protoplasm)
-resists entry of excess water
into the cell
-large empty spaces present
between cellulose fibres
-freely permeable
Cell Membranes
-component of every biological cell
-selectively permeable cell membrane (or plasma membrane
or plasmalemma)
-Phospholipid bilayer was found, which is combine of two
opposite layer of phospholipid, each molecule contain
hydrophilic phosphate head and hydrophobic hydrocarbon
chain
-Cell surface membranes often contain receptor proteins and cell
adhesion proteins.
-One of the key roles of the membrane is to maintain the cell
potential.
- Some function of cell membrane:
-Isolates cytoplasm from external environment
-regulates flow or material into and out of the cell
-allows interaction with other cells
Cytoplasm
-homogeneous, generally clear jelly-like material that fills cells.
-consists of cytosol and the cellular organelles, except the
nucleus.
-made up of water, salts and organic molecules and many
enzymes
-plays an important role in a cell, serving as a "molecular soup"
-plays a mechanical role, i.e. to maintain the shape, the
consistency of the cell and to provide suspension to the
organelles.
-storage place for chemical substances indispensable to life.
-Vital metabolic reactions take place here, for example
anaerobic glycolysis and protein synthesis.
Nucleus
-contains most of the cell's genetic material
-two primary functions: to control chemical reactions within the
cytoplasm and to store information needed for cellular
division.
-Inside the nucleus is one or several nucleoli surrounded by a
matrix called the nucleoplasm. The nucleoplasm is a liquid
with a gel-like consistency (similar in this respect to the
cytoplasm), in which many substances are dissolved. These
substances include nucleotide triphospates, enzymes,
proteins, and transcription factors. There also exists a
network of fibers in the nucleoplasm known as the nuclear
matrix.
-Genetic material (DNA) is also present in the nucleus, the DNA
is present as a DNA-protein complex called chromatin,
present as a number of discrete units known as
chromosomes.
Vacuoles
-serve a variety of different functions:
-capturing food materials or unwanted structural debris
surrounding the cell, sequestering materials that might be
toxic to the cell, maintaining fluid balance (called turgor)
within the cell, exporting unwanted substances from the
cell, or even determining relative cell size.
-typically filled with a liquid called ‘cell sap’, principally water.
-Most mature plant cells have a central vacuole, takes up
more than 80% of the cell interior. -surrounded by a
single-layered membrane, called the tonoplast.
In a plant cell, we can find a lot of
organelles in cytoplasm:
- Chloroplast
- Mitochondria
- Golgi apparatus
- Endoplasmic Reticulum
Chloroplast
-Chloroplasts are organelles found in
plant cells and eukaryotic algae
-conduct photosynthesis.
-similar to mitochondria but are found
only in plants.
-surrounded by a double membrane
with an intermembrane space
-have their own DNA and are involved
in energy metabolism and both
have reticulations, or many foldings,
filling their inner spaces.
-Chloroplasts convert light energy
from the sun into ATP through a
process called photosynthesis.
Mitochondria
-Mitochondria as "cellular power
plants", their primary function
is to convert organic materials
into energy in the form of ATP.
-standard bean-shaped organelle,
ranging from 1 to 4 µm in
length
-living cells
-contains two functionally
distinct membranes: the outer
mitochondrial membrane and
the inner mitochondrial
membrane.
-cristae surface houses
needed for aerobic respiration
and ATP formation, it folded
to increases that capacity by
increasing the surface area
-one within the interior of the
mitochondrion, called the
matrix
-between the inner and outer
membranes, called the
intermembrane space.
Mitochondria
Chloroplast
Golgi apparatus
-primary function is to process proteins targeted to the
plasma membrane as a central delivery system for the cell.
-transport vesicles that leave the endoplasmic reticulum (ER),
specifically rough ER, are transported to the Golgi
apparatus,
-modified, sorted and shipped towards their final destination,
such as enzymes, being secreted.
-is "postal office" of the cell. It handles all incoming lipids,
proteins, etc., and controls their export as well.
-The transport mechanism itself is not yet clear
-As well as protein modification, Golgi apparatus is involved
in the transport of lipids around the cell as well creating
lysosomes -- organelles involved in digestion.
Endoplasmic reticulum
Rough ER
Smooth ER
-rough ER manufactures and
-The smooth ER has functions in
transports proteins destined for several metabolic processes
membranes and secretion.
-takes part in the synthesis of
-synthesizes membrane,
various lipids ,fatty acids and
organellar, and excreted
steroids (e.g., hormones),
proteins. Minutes after proteins
-plays an important role in
are synthesized most of them
carbohydrate metabolism,
leave to the Golgi apparatus
detoxification of the cell, and
within vesicles.
calcium storage.
-also modifies, folds, and
controls the quality of proteins -well developed in cells that
produce steroid hormones and in
liver cells.
Which is Rough ER and Smooth ER?
Rough ER
Smooth ER
Transportation between ER
and Golgi Apparatus
The transport vesicles from the ER fuse with the cis face of the
Golgi apparatus (to the cisternae) and empty their protein content
into the Golgi lumen. The proteins are then transported through
the medial region towards the trans face and are modified on their
way. The proteins are also labelled with a sequence of molecules
according to their final destination.
The transport mechanism itself is not yet clear; it could happen by
cisternae progression (the movement of the apparatus itself,
building new cisternae at the cis face and destroying them at the
trans face) or by vesicular transport. It is also proposed that the
cisternae are interconnected and the transport of cargo molecules
within the Golgi is due to diffusion, while the localisation of Golgiresident proteins is achieved by an unknown mechanism.
Reference source:
- http://www.yahoo.com.hk
- http://en.wikipedia.org/wiki/Main_Page
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