The Structure and Functions of Human Cell-2

Cytoplasm

Additionally known as protoplasm. The mineral-rich fluid is situated between the cell membrane and the nucleus. Except for the nucleus, all of the cellular components found within the plasma membrane are known as cytoplasm. It features two storage spaces:

1. The Cytosol (Intracellular Fluid)

About 55% of the total volume of the cell is made up of this fluid-filled region of the cytoplasm. Water makes between 75 to 90% of cytosol, however its composition and consistency differ from cell to cell. Glucose, proteins, fatty acids, lipids, amino acids, ATP, and waste products are among the additional dissolved and suspended substances that it includes. The inorganic components are soluble in water and hence exist as solutions. Colloids, on the other hand, are the most common kind of organic compounds. Colloids are particles that cling to the surface of the medium they are in. A large number of chemical processes necessary for a cell's survival take place in the cytosol.

2. Organelles:

Organelles are specialized intracellular parts of the cell that have a specific role in growth, maintenance, repair, and regulation. They have a distinctive shape. Some of the organelle structures include:

• Endoplasmic Reticulum:
  • The double membrane channel known as the endoplasmic reticulum, or ER. Along with the nuclear membrane, it is continuous. It entailed material exchange with the cytoplasm inside the cell. The endoplasmic reticulum carries different products from one area of the cell to another. As a result, it is regarded as intracellular transportation and serves as the cell's own little circulatory system. It also serves as a storage space for newly created molecules. It functions as a center for synthesis and packing along with the Golgi complex. Two types of endoplasmic reticulum exist. The two types are granular (rough) endoplasmic reticulum, which contains granule or ribosomes, and agranular (smooth), which lacks ribosomes.
  • Functions of Endoplasmic reticulum:
    •  Rough ER synthesizes glucoproteins and phospholipids.
    •  Smooth ER synthesizes fatty acids and steroids (estrogen and testosterone) and detoxifies drugs.

endoplasmic reticulum

• Golgi Complex:
  • This is made up of several compactly folded, flattened membrane sacs that are located close to the nucleus. It distributes protein to various cell components after processing, sorting, and packing it.
  • Functions of Golgi complex
    • It serves as a short-term protein storage solution.
    • It aids in polysaccharide synthesis.
    • It aids in the creation of proteins, enzymes, and hormones.

Golgi body

• Mitochondria:
  • Small, spherical, rod-shaped, or filamentous structures make up mitochondria. Through aerobic (oxygen-dependent) respiration, they produce energy. They are therefore referred to as the cell's "power house." Each mitochondria has two membranes: an upper, smooth membrane, and a lower membrane with cristae, which are a sequence of folds. The matrix is the inner membrane-enclosed central chamber of a mitochondria.
  • Functions of Mitochondria
    • In the presence of oxygen, it uses glucose to power cells.
    • It aids in finishing the process of cellular respiration.

Mitochondria

• Lysosomes :
• The Golgi complex produces lysosomes, which are membrane-enclosed vesicles with a single membrane. They include potent hydrolytic enzymes, which can hydrolyze a wide variety of compounds. The lysosomal enzyme is thought to be produced in the Golgi complex and granular endoplasmic reticulum.
  • Functions of Lysosomes:
    • It breaks down and digests substances that phagocytosis has carried into the cell.
    • Lysosomes serve as the cell's digestive system by aiding in the digestion of nutrients with the aid of several enzymes.
    • It is also referred to as a "suicide bag" because it can occasionally engulf the user and destroy the cell.
• Cytoskeleton:
  • The cytoskeleton, a collection of extremely tiny microfilaments, microtubules, and intermediate filaments, makes up the intricate internal structure of the cytoplasm.

• Centrosome:
  • It is a compact, spherical region of cytoplasm that is located A pair of centrioles and peri-centriolar material make up its two components. Additionally, it has DNA that manages their replication. Microtubules, which resemble drinking straws, make up centrosmes. They play a role in the chromosome's mobility during cell division.
• Cilia and Flagella:
  • They are microtubule-based extensions that resemble tread. When they beat, rhythmic movement results. They are present in the upper respiratory tract and female reproductive organ.
•  Ribosome:
  • Ribosomal RNA makes up these small granules. They are where proteins are made. There are two categories of ribosomes:
  • Connected ribosomes to the rough endoplasmic reticulum.
  • Cytoplasmic distribution of free ribosomes.
  • Function of Ribosomes:
    • Proteins used in the cytosol are created by ribosomes.

• Nucleus:
  • Because it houses 46 chromosomes, the nucleus is the largest and most important component in a cell. The hereditary component of the cell is located on these chromosomes. As a result, it controls cell structure and activity. The majority of cells have a single nucleus, however others, like mature RBC, do not. Muscle cells, however, have a number of nuclei. Nuclear membrane, a double membrane separating the nucleus from other cell structures (envelop). The double-layered nuclear membrane that surrounds the nucleus and has several pores that allow it to connect with the cytoplasm is located inside the cytoplasm. The genetic material known as chromosomes is found in the nucleus' karylymph (nucleoplasm), a jelly-like fluid that fills the nucleus. Nucleus also contains dark, somewhat spherical, non membrane bound mass called nucleolus.
  • A nucleolus is a tiny structure consisting of DNA, RNA, and protein that helps build ribosomes.
  • Functions of the Nucleus:
    • It regulates the division of cells.
    • Inside the cells, it regulates metabolic processes.
    • It produces RNA and protein.
    • Through the use of chromosomes, it inherits many traits.

Nucleus

• Deoxyribonucleic Acid (DNA):
  • Two polynucleotide chains that have been twisted together to create a double helix make up DNA. A nitrogenous base, a sugar molecule (deoxyribose), and a phosphate molecule make up each nucleotide. Adenine, Guanine, Cytosine, and Thymine are the nitrogenous bases found in DNA (pyrimidines). A pyrimidine on one chain and a purine on the other chain always pair together. Additionally, there are certain base pairings: guanine in one chain always forms a triple bond with cytosine in the other chain, and adenine in one chain always forms a double bond with thymine. The chromosome's nucleus is where DNA is primarily located. Genetic code or information is found in DNA. The DNA found in the chromosomes in the nucleus carries the genetic information. This information is transcribed into RNA in the nucleus, which serves as a messenger.
• Ribonucleic Acid (RNA):  
  • RNA is a considerably smaller molecule than DNA, and it is mostly present in the cytoplasm and nucleolus of cells. Adenine, guanine, and cytosine are all present in both RNA and DNA, but thymine is substituted by uracil in RNA, which also contains the sugar ribose.
  • RNA transports the genetic material found in DNA outside of the nucleus and from the nucleus to the cytoplasm. Messenger RNA (mRNA) migrates to the cytoplasm after copying DNA and joins the ribosome, which is where protein synthesis takes place. In the cytoplasm, transfer (tRNA) combines with complementary bases on the mRNA.
• Chromosome:
  • The somatic cells each have a nucleus that houses a set of 46 (23 pairs) chromosomes. The chromosome includes the fundamental genetic components that determine an individual's characteristics and attributes, such as eye and hair color. Two of the 46 chromosomes are sex chromosomes because they influence sexual behavior. Each man and female contributed one chromosome to the final product.
  • The X and Y chromosomes, which make up sex chromosomes, are the same size and shape for the female and male, respectively. In females, the sex chromosome makeup is XX, while in males, it is XY. Only females exhibit sex chromatin, often known as "X" chromatin or "Barr body." Thus if an 'X'- bearing spermatozoon fertilizes a female, If a'Y'-bearing spermatozoon fertilizes an ovum, the offspring will be male. Therefore, a male's sexchromosome determines the sex of his offspring, which is dependent on that offspring's sex.
  • The remaining 44 chromosomes, in addition to the sex chromosome, influence various traits and behaviors in children.