Cell The Unit of Life Test - 14

The smooth endoplasmic reticulum packages proteins for transport, synthesizes membrane phosolipids, and releases calcium. Other functions of the smooth endoplasmic reticulum include transformation of bile pigments, glycogenolysis (the breakdown of glycogen), and detoxification of many drugs and chemical agents. The smooth endoplasmic reticulum is another organelle in eukaryotic cells that synthesizes lipids. This organelle is located near the rough endoplasmic reticulum, and it produces phospholipids and cholesterol that help stabilize the membranes of the entire cell. The ribosomes in the rough endoplasmic reticulum manufacture proteins. These proteins are manufactured from chains of amino acids. 

• A nuclear membrane, also known as the nuclear envelope, nucleolemma, or karyotheca, is the double lipid bilayer membrane that surrounds the genetic material and nucleolus in eukaryotic cells.
• The nuclear membrane consists of two lipid bilayers - the inner nuclear membrane, and the outer nuclear membrane. The space between the membranes is called the perinuclear space, a region contiguous with the lumen (inside) of the endoplasmic reticulum.
• The nuclear membrane has many small holes called nuclear pores that allow material to move in and out of the nucleus. Rough endoplasmic reticulum produces a nuclear envelope in telophase.

Rough endoplasmic reticulum (RER) are responsible for the assembly of proteins. A signal peptide is a short peptide that is present at the N-terminus of the newly synthesized proteins. It is cleaved by signal peptidase in RER and then enters the lumen of rough endoplasmic reticulum. Protein folding takes place in the lumen of the endoplasmic reticulum. Smooth endoplasmic reticulum (SER) is involved in the synthesis of phospholipid and cholesterol. Protein glycosylation takes place in the  lumen of the RER. Thus, the correct answer is option C.

Correct Option: B

Large clusters of 10 to 100 ribosomes, actively translating protein synthesis are called polysomes. The ribosomes in a polysome are connected by a single molecule of mRNA that is being translated simultaneously by many closely spaced ribosomes.
Polymers are large molecules composed of many monomer units.
Polypeptide is large linear polymer of amino acids bonded together by peptide linkage.
Okazaki fragments are small nucleic acid fragments formed by discontinuous replication of lagging strand during DNA replication and are later joined together by DNA ligase enzyme.
So, the correct answer is option A.

Nucleus is the double membrane bound organelle of eukaryotic cells that serve to house genetic material. The two membranes together makes the nuclear envelope.
Mitochondrion is double membrane bound organelle, wherein the inner membrane is present as infolding and forms cristae. Cristae have respiratory enzymes and serve as a site for cellular respiration.
Chloroplast is double membrane bound organelle in which the inner membrane surrounds the alkaline stroma and thylakoid system.
Lysosomes are bound by single layer of typical phospholipids.
So, the correct answer is option C.

• When ribosomes are present in the membrane of the endoplasmic reticulum it is called the rough endoplasmic reticulum. 
• RER is abundantly found in the cells that actively synthesize proteins. The synthesis of lipids takes place in the smooth endoplasmic reticulum.

Ribosomes are the protein factory of a cell. These are non-membranous organelle which attaches on endoplasmic reticulum by transcolon.

Metachromatic granules are the cell inclusions mostly found in the prokaryotic cell. It appears red, when stained with blue dyes in certain bacteria, yeasts, yeast like fungi, and protozoa. They are composed of complex polyphosphate, lipid, and nucleoprotein molecules (volutin) and serve as an intracellular phosphate reserve also called as Babes ernst body or granule.