Question

How is cell organized ? answer for std 9 student

Answer 1

• Cells are divided into several compartments, each with a characteristic structure, biochemical composition, and function.

• These compartments are called organelles. They are delimited by membranes composed of phospholipid bilayers and a number of proteins specialized for each type of organelle.

• All eukaryotic cells have a nucleus surrounded by a nuclear envelope, and a plasma membrane that borders the whole cell.

• Most eukaryotic cells also have endoplasmic reticulum, a Golgi apparatus, lysosomes, mitochondria, and peroxisomes.

• Plant cells have chloroplasts for photosynthesis in addition to the organelles that both they and animal cells possess.

• These organelles are suspended in a gellike cytoplasmic matrix composed of three types of protein polymers called actin filaments, microtubules, and intermediate filaments.

• In addition to holding the cell together, the actin filaments and microtubules act as tracks for several different types of motor proteins that are responsible for cell motility and organelle movements within the cytoplasm.

• The cell must possess enough information to specify which molecules are to be associated in a specific compartment, to route the appropriate groups of molecules to their compartments, and then to position each type of component appropriately in the cell.

• As a result of intense research on each of these topics, a number of specific chemical reactions that contribute to organizing cells are now recognized, but even more important, a small number of general principles that explain these complex processes of life can be appreciated.