4. Describe the five cellular structures that are present in the plant cell but
ID: 212907 • Letter: 4
Question
4. Describe the five cellular structures that are present in the plant cell but not in the animal cell and major functions of each of those structures.5. Where is the insulin molecule produced in the cell? What organelles/structures it has to pass through before it is released to the outside of the cell and into the blood stream? 4. Describe the five cellular structures that are present in the plant cell but not in the animal cell and major functions of each of those structures.
5. Where is the insulin molecule produced in the cell? What organelles/structures it has to pass through before it is released to the outside of the cell and into the blood stream? 4. Describe the five cellular structures that are present in the plant cell but not in the animal cell and major functions of each of those structures.
5. Where is the insulin molecule produced in the cell? What organelles/structures it has to pass through before it is released to the outside of the cell and into the blood stream?
Explanation / Answer
Answer 4. The 5 cellular structures that are present in the plant cells but not in the animal cells are as follows:
1. Cell wall: Cell wall is a rigid layer found outside the cell membrane specifically in plant cells and not in animal cells. Cell wall contains cellulose, proteins and other polysaccharides. Function of cell wall is to provide structural support and protection from the harsh environment.
2. Chloroplast: Plant cells use sunlight as the energy source and they need chloroplast to carry out this process. Photosynthesis is carried out with the help of chloroplasts and it is not present in animal cells.
3. Central vacoule: Most plants have central vacoule that makes up about more than 30% of cell's volume. It is surrounded by a membrane called the tonoplast. Central vacoule has many functions such as storage and maintenance of turgor pressure. It also stores pigments that give color to flowers.
4. Chromoplasts: They produce and store pigments that give petals and fruits their orange and yellow colors.
5. Leucoplasts: These are located in the roots and do not contain pigments. These are known as the non photosynthetic tissues of plants. They are used for bulk storage of lipids, starch and proteins.
Answer 5. Beta cells in the islet of langerhans in pancreas are the specialized cells that produce, store and release the harmone called insulin. The insulin mRNA is translated as a single chain precursor called peproinsulin. A signal peptide attached to it guides it to endoplasmic reticulum and when this signal peptide is removed it generates proinsulin.
Proinsulin has 3 chains amino terminal B chain, carboxy terminal A chain and a connecting peptide known as C peptide. Digestion by endopeptidases in the endoplasmic reticulum excises C peptide and generates mature insulin. Insulin is then packaged in the Golgi which is furthur accumulated in the cytoplasm. When beta cells are stimulated insulin is secreted by the cells via exocytosis and diffuses into islet cappilary blood.
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