Table of Contents
How are nucleoli formed?
The formation of nucleoli requires the transcription of 45S pre-rRNA, which appears to lead to the fusion of small prenucleolar bodies that contain processing factors and other components of the nucleolus. In most cells, the initially separate nucleoli then fuse to form a single nucleolus.
Which structure plays a role in the synthesis of steroid based hormones and proteins?
The proteins made by the rough endoplasmic reticulum are for use outside of the cell. Functions of the smooth endoplasmic reticulum include synthesis of carbohydrates, lipids, and steroid hormones; detoxification of medications and poisons; and storage of calcium ions.
Why is the nucleolus dense?
The bulk of the nucleolus is the granular component (GC), where rRNA and proteins assemble to the ribosomal subunit (Fig. The nucleolus is typically visible as a dark region of low DNA density by DAPI DNA stain, due to the abundance of ribosomal RNA and proteins assembling throughout most of the nucleolus.
What are hollow cytoskeletal elements that act as organizers for the cytoskeleton?
Microtubules. As their name implies, microtubules are small hollow tubes. Microtubules, along with microfilaments and intermediate filaments, come under the class of organelles known as the cytoskeleton.
What is the dense fibrillar component?
A structure found in the nucleolus, which contains newly synthesized preribosomal RNA (pre-rRNA) and a collection of proteins. [
What is steroid synthesis?
Steroid biosynthesis is an anabolic pathway which produces steroids from simple precursors. A unique biosynthetic pathway is followed in animals (compared to many other organisms), making the pathway a common target for antibiotics and other anti-infection drugs.
Which organelle are steroid hormones synthesized?
STEROID-SECRETING CELLS are characterized by abundant smooth endoplasmic reticulum (SER). These cells synthesize cholesterol as a precursor for steroid hormones or take up this substrate from plasma lipoproteins.
What is the site of synthesis of ribosomal RNA?
the nucleolus
Molecules of rRNA are synthesized in a specialized region of the cell nucleus called the nucleolus, which appears as a dense area within the nucleus and contains the genes that encode rRNA.
Does the nucleolus make RNA?
The nucleolus is a round body located inside the nucleus of a eukaryotic cell. It is not surrounded by a membrane but sits in the nucleus. The nucleolus makes ribosomal subunits from proteins and ribosomal RNA, also known as rRNA.
What is the function of the cytoskeleton in eukaryotic cells?
The cytoskeleton of eukaryotic cells is made of filamentous proteins, and it provides mechanical support to the cell and its cytoplasmic constituents. All cytoskeletons consist of three major classes of elements that differ in size and in protein composition.