Cell - The Unit of Life Test - 5

Cytoplasmic matrix is often differentiated into outer gel part called as ectoplasm and inner sol part called as endoplasm. In a living cell, the endoplasm is usually in perpetual motion called as cyclosis or cytoplasmic or protoplasmic streaming. 

Mitochondria is also called chondriosome. This is the scientific name for a cell organelle. It is responsible for cell respiration (a process which produces energy). That's why, it is also called as “Power house of the cell”.

RNA occurs in the nucleus as well as in the cytoplasm of the eukaryotic cells and in prokaryotic cell, it is found in the cytoplasm. DNA is found in the nucleus, mitochondria and chloroplast. Chloroplast and sphaerosomes are found only in cytoplasm.

Mitochondria is the site for aerobic respiration in cell and produces energy in the form of ATP. For the formation of energy different pathways like electron transport chain, kreb's cycle are involved and operated by the different enzymes. Thus, the maximum number of enzymes are found in  mitochondria. 

Rough endoplasmic reticulum carry ribosomes on their surface. The ribosomes present on rough endoplasmic reticulum synthesize secretory proteins. The proteins required for internal use of cell are synthesized on cytoplasmic ribosomes.

Golgi apparatus is the membrane bound organelle which consists series of flattened stacks. It plays an important role in the storage, packaging and secretion of certain cell products. It is involved in the formation of lysosomes and other enzyme-containing cellular inclusions, and in the formation of secretory granules.

Thus, the correct answer is option A.

 The basic proteins associated with DNA are the well- known protamines and histones; traditionally these have been regarded as principal constituents of the cell nucleus because DNA was considered.
Nucleus histones are called histone proteins and the resulting DNA- protein complex is called chromatin. Chromosomes are composed of DNA tightly- wound around histones. Chromosomal DNA is packaged inside microscopic nuclei with the help of histones. 
Protamines are small, arginine- rich, nuclear proteins that replace histones late in the haploid phase of spermatogenesis.

TCA or Tricarboxylic Acid Cycle or Krebs cycle oxidizes the compounds like acetyl-CoA obtained from carbohydrates, fats and proteins and leads to the production of carbon dioxide and energy in form of ATP.

Mitochondria are cell organelles involved in aerobic respiration. Krebs cycle occurs in the mitochondrial matrix. Krebs cycle produces reduced coenzymes which are oxidized by electron carriers of Electron Transport System or ETS to produce ATP through oxidative phosphorylation. The electron carriers of ETS are located in the inner mitochondrial membrane in eukaryotes.

Smooth endoplasmic reticulum secretes zymogen. The smooth endoplasmic reticulum has functions in several metabolic processes. It synthesizes lipids, phospholipids, and steroids

In a eukaryotic cell, DNA is also present in organelles like mitochondria and chloroplasts in addition to the nucleus. The DNA present in organelles resembles prokaryotic DNA. It is circular and devoid of histone proteins unlike the DNA present in nucleus which is linear and is wound around histone protein core. The mitochondrial DNA is a double stranded molecule.
So, the correct answer is 'All of the above'.

Sphaerosomes are single half unit membrane covered small spherical organelles in plants which synthesize and store fats. They develop from endoplasmic reticulum. Smooth endoplasmic reticulum are devoid of ribosomes and carry out synthesis of lipids, detoxification, synthesis of steroids in animals.

In most eukaryotes, the Golgi apparatus is made up of a series of compartments and is a collection of fused, flattened membrane-enclosed disks known as cisternae (singular: cisterna, also called "dictyosomes"), originating from vesicular clusters that bud off the endoplasmic reticulum.

The first cell was observed and named by Robert Hooke in 1665. He described that it looked like cellula, small rooms which are inhabited by monks hence derived the name 'cell'. The cell he actually saw was the dead cell walls of the plant (cork) under a microscope. Hooke described the characteristics of a cell he observed in his book 'Micrographia'.

Excessive secretory granules of hormone in endocrine gland may be digested by lysosomes. This event is called crinophagy. Thyroglobulin stores in thyroid gland with its follicles and after crinophagy by proteases itproduces thyroxine.

Golgi apparatus produces materials for secretion, takes part in the transformation of membranes, the formation of a number of products from glycoproteins, e.g., mucin in goblet cells, complex heteropolysaccharides e.g., mucilage in root cap cells, hormones in plant cells as well as acrosome in sperms and lysosomal vesicles. Acrosome is a cap-like structure which contains digestive enzymes. The digestive enzymes in acrosome help in piercing the ovum.

The endoplasmic reticulum is the double membrane bound organelle. It is or two types on the basis of the presence of ribosomes. Endoplasmic reticulum which lacks ribosomes is called smooth endoplasmic reticulum (SER). The SER occurs in cells engaged in producing a lot of lipids. SER takes part in the synthesis of vitamins, carbohydrates, and detoxification. SER is also involved in a number of other reactions like the synthesis of bile, precursors of steroid hormones from cholesterol. Endoplasmic reticulum which possesses ribosome called as rough endoplasmic reticulum which involved in the formation and transportation of proteins.

Ribosomes are cell organelles which carry out protein synthesis. Prokaryotes have 70S ribosomes and eukaryotes have 80S ribosomes. Ribosomes are found freely in cytoplasm as wells in or attached to some organelles.
Mitochondria have 55S ribosome. They have small 28S and large 39S subunits which together form 55S mitoribosome (mitochondrial ribosome). 
So the correct answer is " 55S "

Phospholipid synthase enzyme occur in smooth endoplasmic reticulum. The smooth endoplasmic reticulum has functions in several metabolic processes. It synthesizes lipids, phospholipids, and steroids. Cells which secrete these products, such as those in the testes, ovaries, and skin oil glands have a great amount of smooth endoplasmic reticulum. It also carries out the metabolism of carbohydrates, drug detoxification, attachment of receptors on cell membrane proteins, and steroid metabolism.

Endoplasmic reticulum (ER), in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins . All eukaryotic cells contain an endoplasmic reticulum (ER). In animal cells, the ER usually constitutes more than half of the membranous content of the cell. Differences in certain physical and functional characteristics distinguish the two types of ER, known as rough ER and smooth ER.

Lysosomes are membrane-enclosed organelles and consist of hydrolytic enzymes which capable of breaking down all types of biological polymers (like proteins, nucleic acids, carbohydrates, and lipids). If lysosomes get ruptured in a cell, the cell dies due to release of hydrolytic enzymes which destroys the cells.

Mitochondria are eukaryotic cell organelles. Mitochondria synthesize ATP through the process of aerobic respiration. Hence, mitochondria are called powerhouse of the cell. Carbohydrates are the most common fuel used to derive energy in aerobic respiration. When carbohydrates are in short supply, fats and proteins can also be used in aerobic respiration as reduced substrates. Thus, the correct answer is option D.

F₁ particles are also known as oxysomes or elementary particles or F₁-F₀ particles. These particles are present in matrix side of mitochondrial inner membrane. In mitochondria, F₁ particles function in synthesizes ATP from ADP + Pi. F₁ particles comprise about 15% of the total inner membrane protein.

Like the conversion of pyruvate to acetyl CoA, The Citric Acid (Krebs) cycle takes place in the matrix of the mitochondria. Almost all of the enzymes of the citric acid cycle are soluble, with the single exception of the enzyme succinate dehydrogenase, which is embedded in the inner membrane of the mitochondrion.

The peptidyl transferase is an aminoacyltransferase, it performs the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis. Peptidyl transferase activity is carried out by the ribosome. Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme.

F₁ particle of the ATPase (or oxysome) is also called the head part.

During ATPase action, the PMF (Proton motive force) do not allow stay of protons in the perimitochondrial space, so they return to the matrix through the F₀ part selectively, thus breaking the potential.

This breaking of potential generates enough energy to make some conformational changes in the F₁ particle, which leads to conversion of ADP into ATP.

Dictyosomes are the set of flattened membranes in a Golgi body, resembling a stack of plates. Microtubules transport the cell wall material from dictyosome. Microtubules are very important in a number of cellular processes. They are involved in maintaining the structure of the cell and together with microfilaments and intermediate filaments, they form the cytoskeleton. Microtubule ends are often localized to particular structures which transport cell wall material.