Plant Cell Structure

     You pass by a flower shop, or see pretty flowers planted in a yard, or meadow. The flowers you see, and all the plants you get your vegetables from all have a "heart". Every plant is broken down, and all start with  a plant cell. Plant cells are important to cells because they are the basic units of life. There are many parts involved in a cell. All of them are important too, but there is one place where everything starts. The nucleus. The nucleus is en closed in a double membrane and communicates with the surrounding cytosol in numerous nuclear pores. In the nucleus is the DNA,which is responsible for providing the cell with its one of a kind characteristics. The DNA is similar in every of every body, but depending on the cell type, some genes may be turned on and off. This is why a liver cell is different from a muscle cell (giving an example). when a cell divides, the nuclear chromatin condenses into chromosomes that can be seen easily by a microscope.

     The Nucleolus. The Nucleolus is the first thing you notice in the nucleus, it is the most obvious structure. The nucleolus produces ribosomes, which move out of the nucleus and position themselves on the rough endoplasmic reticulum where they are very important in protein synthesis.
     The Cytosol. The Cytosol is what they call the "soup" where all the other cells organelles reside and where most of the metabolism occurs. Mostly through water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors.

     The Cytoplasm. The Cytoplasm is just a collective term for the cytosol, plus the organelles suspended within the cytosol.

     The Centrosome. The centrosome of MTOC (Microtubule Organizing Center) is the area in the cell where microtubules are produced. Plant and animal cell centrosomes play similar roles in the division of cells. Both of them include collections of microtubules, but the plant cell centrsome is simpler and does not have centrioles. 

     The Golgi. The Golgi is a membrane-bound structure with a single membrane. It is actually a stack of membrane-bound vesicles important in packaging macromolecules for transport somewhere else in the cell. The stack of larger vesicles is surrounded by many smaller vesicles having those packaged macromolecules. The enzymatic or hormonal contents of lysosomes, peroxisomes and secretory vesicles are packaged in membrane-bound vesicles at the periphery of the Golgi. 

     The Lysosome. Lysosomes contain hydrolytic enzymes that are necessary for intracellular digestion. They are mostly seen in animal cells, but sometimes in plant cells. Hydrolytic enzymes of plant cells are usually found in the Vacuole. 

     The Peroxisome. Peroxisomes are membrane-bound packets of oxidative enzymes. With plant cells, they play  many roles like converting fatty acids to sugar and guiding chloroplasts in photorespiratioin. Oxidative enzymes in peroxisomes break down hydrogen peroxide into oxygen and water.

     Secretory Vesicle are cell secretions of e.g. hormones, neurotransmitters secured in secretory vesicles in the Golgi. The secretory vesicles are then transported to the cell surface for release.

     The Cell Membrane. All cells are enclosed in a membrane, a double layer of phospholipids. The exposed heads of hte bilayer are hydrophillic, which means that they are compatible with water both in they cytosol and outside of the cell. But the tails of the phospholipids are hydrophibic, so the cell membrane acts as a protective barrier to the flow of water that is uncontrolled. The membrane is more complex by the presence of many protiens that are very important to the activity of the cell. These protiens include receptors for odors, tastes and hormones, and pores responsibole for controlled enter and exit of ions like sodium, potassium, calcium, and chloride.

      The Mitochondria. Mitochondria provide energy a cell needs to move, divide, make secretory products contract- in short, these are the power centers of the cell. They are small, like the size of bacteria, but can have different shapes depending on the cell type. They are membrane-bound orangelles, and have a double membrane, like the nucleus. The outter membrane is smooth. But the inner membrane is highly convoluted. The cristae increase the inner membrane's surface area. It's on these cristae that food is combined with oxygen to produce ATP, which is the primary energy source for the cell.  

    The Vacuole. A vacuole is a membrane-bound sac that plays roles in intracellular digestion and the output of cellular waste. Vacuoles play a big part in plant cells. They play several roles like storing nutrients and waste products, helping increase cell size during the growth process. They even act like lysosomes in animal cells. It also regulates tug or pressure on the cell. Water collects in cell molecules, pressing out against the cell wall producing rigidity in the plant. Without sufficient water, turgor pressure drops and the plant will wilt.

     The Cell wall. The cell is in plant cells only. Plant cells have a rigid, protective cell wall made of polysaccharides. In bigger planet cells, the polysaccharide is mostly cellulose.  The cell wall provides and helps keep the shape of the cells and serves as a protective barrier. Fluid collects in the the vacuole and pushes out against the cell wall. This turgor pressure is responsible for the fresh vegetables crispness. 

     The Chloroplast. Chloroplast is in plant cells only also. Chloroplasts are organelles found in all higher plant cells. These organelles contain the plant cell's chlorophyll which makes the plants green like they are. Chloroplasts have a double outer membrane. In the stroma are other membrane structures like thylakoids. Thylakoids show up in stacks called grand. 

     The Smooth Endoplasmic Reticulum. Throughout the eukaryotic cell, especially those responsible for the production of hormones and other secretory products, is a large network of membrane-bound vesicles and tubules called the Endoplasmic reticulum. The ER is a continuation of the outer nuclear membrane and its functions vary and suggest the complexity of the eukaryotic cell. The Smooth ER has its name because it is shown as smooth by electron microscopy. The Smooth ER plays different functions depending on the specific cell type.

     Rough Endoplasmic Reticulum. The Rough ER shows to be pebbled by electron microscopy due to the presence of many ribosomes on its surface. Proteins synthesized on these ribosomes collect in the ER for transport throughout the cell. 

     Ribosomes. Ribosomes are packets of RNA and protein that play a very important role in both prokaryotic and eukaryotic cells. They are the site of protein synthesis. Each ribosome comprises two parts, a large submit and a small submit. Messenger RNA from the nucleus is moved along the ribosome where transfer RNA adds individual amino acid molecules to the protein chain.

    The Cytoskeleton. The cytoskeleton helps maintain the cells shape. The importance of the cytoskeleton is cell motility. The internal movement of the organelles, as well as the cell locomotion could not take place without the cytoskeleton. The cytoskeleton is an organized network of three primary protein filaments such as microtubules, actin filaments, and intermediate fibers.