B) Nucleoli are large protein complexes that cross the nuclear envelope in eukaryotic cells.
C) Nucleoli are thin, dense meshworks of fibers lining the inner surfaces of the inner nuclear membranes of most eukaryotic cells.
D) Nucleoli are structures made of DNA, RNA, and protein that are present in the eukaryotic nucleus.
Answer:
Option-D
Explanation:
The nucleolus is a structure present in the nucleus of the cell which is important for the cell.
The nucleolus provides the site of transcription of the rRNA genes and the enzymes required for transcription. The nucleoli appear condensed structure as the rRNA genes, some portion of DNA and the proteins in the form of the enzymes like RNA polymerase I.Therefore, nucleoli are made of the DNA, RNA and the proteins.
Thus, Option-D is correct.
Answer: Option D
Explanation:
The nucleolus is the largest structure which is found in the nucleus of the eukaryotic cells. It is the main site for the ribosome biogenesis.
Nucleoli consists of DNA and RNA, proteins and it forms around the nucleolar organizing regions. it also help in cell signaling.
These are like envelops which bounds the nucleus inside it. In case of the treatment of cancer, the main target is nucleolus.
b. Scanning electron microscope
c. Compound light microscope
d. Dissecting microscope
Compound light microscope would be the best microscope to view living single-celled organisms in a sample of pond water
B. helped to spread the Renaissance to northern Europe
C. weakened the prestige of the popes
D. strengthened the overseas trade of Italy
Mitochondria and chloroplasts are organelles of a cell possess their own DNA. Thus, option (b) is correct.
In both plant and animal cells, mitochondria are membrane-bound organelles that are essential for producing the chemical energy required for the cell's metabolic processes.
On the other hand, chloroplasts, which are only present in plant cells, are in charge of photosynthesis. Both organelles are involved in protein synthesis and have their own genetic material.
As a result, the significance of the organelles of a cell possess their own DNA are the aforementioned. Therefore, option (b) is correct.
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Answer: D. They act to break down the protective barriers around the egg, allowing the sperm.
Explanation:
Acrosin and other protease enzymes functions by the catalyzing the proteolysis, that is the breakdown of proteins into small polypeptides by cleaving the peptide bonds within the proteins by the process of hydrolysis.
The acrosine and other protease enzymes are released by the acrosome cap of the spermatozoa. This process facilitates the enzymatic digestion of zona pellucida layer of the egg. This helps in the penetration of egg by the sperm.
Answer:
The scanning electron microscope allows the elaboration of an image in which the surface characteristics of the sample are reflected, thus providing sufficient information on the shapes, textures, and chemical composition of the constituents.
Explanation:
The scanning electron microscope uses electrons instead of light for imaging.
To achieve this, the team has a device that produces an electron beam that allows the entire sample to be illuminated and, through different detectors, the electrons that are produced from the interaction with the surface of the sample are later collected.