Cell - The Unit of Life Test - 8

A eukaryotic cell has DNA in nucleus as well as cell organelles like mitochondria and chloroplasts. The DNA in cell organelles resembles prokaryotic DNA. These organelles (mitochondria and chloroplasts) not only have DNA but also their own protein synthesis machinery. These organelles are double membrane bound and can divide through fission independent of nuclear division. Thus these cell organelles are semi-autonomous.

Golgi body is a cellular organelle that is part of the cytoplasmic membrane system; it is composed of regions of stacked cisternae and it functions in secretory processes. Prokaryotes, mature mammalian RBCs and the akaryotes (cells without the nucleus) lack the Golgi bodies.

Chloroplasts are the site of photosynthesis.So, the end product of photosynthesis involves releasing of oxygen. As chloroplast is the site so oxygen is released from there.

Friedrich Meves, in 1904, made the first recorded observation of mitochondria in plants (Nymphaea alba) and in 1908, along with Claudius Regaud, suggested that they contain proteins and lipids. Hofmeister and Kollik discoveries were not related to mitochondria in plants.

Lomasomes are present outside the plasma membrane but inside the cell-wall. They are membranous structure, often containing internal membranes, located between the plasma membrane and cell wall of plant cells. Lomasomes, appear to be accumulations of ejected material between the plasmalemma and cell wall that have become sequestered by the deposition of wall material. Thus, the correct answer is option C.

Lysosome containing bone cells are called as osteoclasts. It is involved in maintenance and repair, and remodeling of bones of the vertebral skeleton. This process is known as bone resorption.

Endoplasmic reticulum are made up of three kinds of structure, cisternae, tubules and vesicles.
Cisternae are found in cells actively involved in protein synthesis.Tubules are common in cells involved in lipid and sterol syntheis.Vesicles are found in pancreatic cells and spermatocytes.
Smooth endoplasmic reticulum when observed under a microscope give the apperance of smooth tubular structure.Smooth ER are function in the synthesis of lipids and steriods.

Eukaryotic cells are more complex than prokaryotic cells and are found in a great many different forms. The nucleus contains most of the genetic material (DNA) of the cell. Additional DNA is in the mitochondria and (if present) chloroplasts.

Option (c)  E. R is the correct answer. 

Explanation:-

Endoplasmic reticulum ( ER) is a system of membrane - lined channels found in all eukaryotic cells except mature     erythrocytes. It constitutes more than  30-60 percent of total cell membranes. It provides protein and lipid to form the structure of cell membrane.

Golgi bodies are mostly found in eukaryotic cells. It was identified in 1897 by the Italian physician Camillo Golgi and named after him in 1898. There were many other names suggested for this cell organelle. After first observing it under his microscope, he termed the structure as the internal reticular apparatus. Some of the cell biologists opposed the discovery at first, arguing that the appearance of the structure was merely an optical illusion created by the observation technique used by Golgi. With the development of modern microscopes, the discovery was confirmed. Early references to the Golgi referred to it by various names including the "Golgi-Holmgren apparatus", "Golgi-Holmgren ducts", and "Golgi-Kopsch apparatus. The term "Lipido chondria" was also suggested for Golgi apparatus.

Golgi components are bound by a single unit membrane and its series forms Golgi apparatus. The Golgi apparatus is involved in proteins secretion, the formation of the lysosome, synthesis of cellulose and hemicellulose etc.

Lysosomes contain acid hydrolase enzymes that break down waste materials and cellular debris. They can be described as the stomach of the cell. Lysosomes digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. The membrane around a lysosome allows the digestive enzymes to work at the pH they require. At pH 5, the lysosomal enzymes remain active and this pH is best suited for enzyme.

Golgi body is the series of flattened stacks which has two faces cis face towards the ER side and trans face opposite of ER. The main function of Golgi complex is the packaging of materials for secretion. The Golgi apparatus is a major collection and dispatch station of protein products received from the endoplasmic reticulum (ER). The Golgi apparatus is also involved in lipid transport and lysosome formation. It also involved in the synthesis of cellulose and hemicellulose.

SDH or Succinate dehydrogenase or respiratory complex 2 is an enzyme complex found in many bacterial cells and in the inner mitochondrial membrane of the eukaryotic cells. It is the only enzyme which participates in both the citric acid cycle and the electron transport chain.

So, the correct answer is " inner membrane ".

Packaging of materials for secretion
The main function of the Golgi apparatus is to modify, sort and package the macromolecules that are synthesized by the cells for secretion purposes or for use within the cell. 

Lysosomes are known as polymorphic cell organelles. Actually polymorphism is the occurrence in several different shapes particularly in reference to species or genetic variation. Lysosomes occur in more then one forms inside the cell.

The polymorphism of lysosomes can be explained on the basis of the types of lysosomes:

1.Primary lysosomes: They are small, newly formed structures formed in golgi apparatus, and they contain inactive enzymes.

2.Secondary lysosomes: They are formed when phagosomes fuse with already present primary lysosomes. Unlike primary lysosomes, they have enzymes against the material which is to be digested, and this is the function of lysosome.

3.Residual bodies:They are formed from digestive and autophagic vacuoles and contains undigested materials

4.Autophagic vacuoles:They are formed by union of primary lysosome around dead/dead organelles. and digest them by autodigestion.

The main source of cellular membranes is the endoplasmic reticulum. Smooth endoplasmic reticulum is located towards the cell membrane produces and transports lipid molecule and the cell membrane is made up of phospholipid bilayer structure. Thus E.R. provides a backbone to the cell membrane.

Lysosomal membranes are sensitive to many labilizers and stabilizers.  Vitamins like A, B, K and hormones like progesterone, B-esterdiol and some metal ions like Ag2+, Hg2 +, Cu2 labilize the membranes and allow the enzymes to diffuse out.  But cholesterol, cortisones, etc stabilize the membranes. 
so option C

The nuclear membrane originates from  Endoplasmic Reticulum.
It is formed by the fusion of ER elements during the telophase of cell division.
The nuclear membrane envelops the nucleoplasm of the cell and acts as a barrier between the nuclear DNA and the cytoplasm. The composition of the nuclear membrane network is complex and incompletely understood, but it provides a structural framework to support and protect the nucleus.