Question

1. Describe in detail the functions of the following organelles: Ribosomes, endoplasmic reticulum (rough and smooth), golgi complex, lysosomes, peroxisomes, mitochondria, and chloroplasts.

Answer 1

Ribosomes: ribosomes are granular structure first observed under electron microscope as dense particle by George palade . They are composed of ribonucleic acid and proteins and are not surrounded by any membrane. day function for the synthesis of protein which is necessary for translational process. Best synthesis proteins from amino acid during translational process.they are found in both eukaryote and prokaryote cell in prokaryotes cell the ribosome is 70s with smaller subunit 30s and larger subunit 50s. In eukaryote 80s with smaller subunit 40s and larger subunit 60s.

Endoplasmic recticulum: there are network for recticulum of tiny tubular structures scattered in the cytoplasm which is called endoplasmic reticulum. ER divides the intracellular space into two distinct compartments luminal and extraluminal . The ER often show ribosomes attached to their surface the endoplasmic reticulum bearing ribosome on their surface is called a rough endoplasmic reticulum in the absence of ribosome they appear smooth and are called smooth endoplasmic. reticulum of endoplasmic reticulum is frequently observed in cells actively involved in protein synthesis and secretion they are extensive and continuous with the outer membrane of nucleus the smooth endoplasmic reticulum is major site for lipids synthesis. They also play major role in synthesis of steroid hormones. the protein which synthesis is directed to the Golgi apparatus by the endoplasmic reticulum. in the absence of transport signal the protein will be stored in the endoplasmic reticulum. The lumen of endoplasmic reticulum serve as a site of modification, assembly and folding of protein.

Golgi apparatus :They are flatshaped, disc shaped sacs or cisternae. These are stacked parallel to each other. The Golgi cisternae are concentrically arranged nearthe nucleus With distinct convex sis or the forming face and concave trans or the maturing face. Though the sis and trans faces of the organelle are entirely different but they are interconnected . The Golgi apparatus principally perform the function of packaging materials to be delivered either to the intracellular targets are secreted outside the cells . Materials to be packaged in the form of basic words from the fuse with this is face of the Golgi apparatus and move towards the maturing face, this explains why the Golgi apparatus remains in close association with the endoplasmic reticulum in number of proteins synthesized by ribosome or endoplasmic reticulum is modified in the cisternae of the Golgi apparatus before they are released from the trans face . Golgi apparatus is the important site of formation of glycoproteins and glycolipids.

lysosomes: These are vesicular structures formed by process of packaging in the Golgi apparatus. The isolated lysosomal vesicles have been found to be very rich in almost all type of hydrolytic enzymes . These enzymes are capable of digesting carbohydrates , proteins, lipids and nucleic acids. They are non as suicidal bags. They are involved in waste removal and digestion of unwanted materials such as antigen antibody complex, phagocytosis cells etc.

peroxisome: peroxisomesperoxisomes are membrane bound minute vesicles called microbody that contain various enzymes.peroxisomes are found in both plants and animals in plants they break down fatty acids in order to convert into sugar and help in photo respiration. In animal cells the peroxisome helps in breaking down of hydrogen peroxide that is it perform oxidation. They also perform function for synthesis of membrane lipids such as plasmogen.

mitochondria:mitochondria is a double membrane bound structure with the outer membrane and inner membrane dividing its lumen distinctly into two equations compartment that is out and compartment and inter compartment . The inner compartment is matrix outer membrane forms the continuous limiting boundary of the organelle.The inner membrane forms a number of infoldings called the Cristae towards the matrix. The Cristae increases the surface area the two membrane have their own specific enzyme associated with the mitochondria function . mitochondria are sites of aerobic respiration that produce seller energy in the form of ATP hence they are called powerhouse of the cell The Matrix also process single circular DNA molecule if you are in a molecule and the components required for the synthesis of protein. mitochondria also play a role in storage of calcium, in apoptosis and also in heat production through non shivering thermogenesis.

chloroplast: chloroplast chloroplast are also double membrane bound organelles. Dekh contain enzymes required for the synthesis of carbohydrates and proteins required for their function. The main functions of chloroplast is photosynthesis that is production of energy and the the storage of energy.