Test: Cytoplasm - NEET MCQ

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 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.

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'.

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'.

• The nuclear matrix or the nucleoplasm contains the nucleolus and chromatin.
• The nucleoli are spherical structures present in the nucleoplasm and the chromatin is present along with it.

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.

• Structure and Function: Mitochondria are membrane-bound organelles found in the cytoplasm of eukaryotic cells. They are often referred to as the powerhouse of the cell because they are responsible for producing the majority of the cell's ATP, which is the main source of energy for cellular activities.



• ATP Production: Mitochondria carry out aerobic respiration, a process that uses oxygen to convert nutrients such as glucose into ATP through a series of complex biochemical reactions. This ATP is then used by the cell to fuel various processes including growth, repair, and movement.



• Role in Cell Metabolism: In addition to ATP production, mitochondria also play a role in other metabolic processes such as the synthesis of certain molecules and the regulation of calcium levels within the cell. They are also involved in cell signaling and apoptosis (programmed cell death).



• Number and Distribution: The number of mitochondria in a cell can vary depending on the energy requirements of that cell. Cells with high energy demands, such as muscle cells, may have thousands of mitochondria, while cells with lower energy needs may have fewer. Mitochondria are distributed throughout the cell to ensure that energy is readily available wherever it is needed.



• Importance: The proper functioning of mitochondria is essential for the overall health and survival of the cell. Any dysfunction in these organelles can lead to a variety of disorders and diseases, including metabolic disorders, neurodegenerative diseases, and aging-related conditions.

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.

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.