A gene is the smallest physical and functional unit of heredity that can be observed. DNA is the building block of genes. Some genes serve as instructions for the production of the molecules known as proteins. Many genes, on the other hand, do not code for proteins. Genome size varies greatly amongst humans, from a few hundred DNA bases to more than 2 million DNA bases. It has been estimated that humans have between 20,000 and 25,000 genes, according to a collaborative multinational research effort known as the Human Genome Project, which aimed to discover the sequence of the human genome and identify genes that it contained.
Each and every person has two copies of each gene, one from each parent. Each person has two copies of each gene. There are only a few genes that aren’t the same in everyone. They make up less than 1% of the total, but they make people different. DNA bases that make up each allele are the same, but they have a very small difference in the order in which they are found in each of them. These small differences help make each person look unique.
The way that scientists keep track of genes is to give them names that are different from each other. People also give each gene a symbol that is made up of letters (and sometimes numbers) that represent an abbreviation of the gene name.
Structure of human gene
Except for some viruses, which have genes made of a closely related molecule called ribonucleic acid, genes are made of deoxyribonucleic acid (DNA) (RNA). A DNA molecule is made up of two nucleotide chains that spiral around each other to form a twisted ladder. The sides of the ladder are composed of sugars and phosphates, while the rungs are composed of bound pairs of nitrogenous bases. Adenine (A), guanine (G), cytosine (C), and thymine are the bases involved (T). An A on one chain bonds to a T on the other (creating an A–T ladder rung), while a C on one chain bonds to a G on the other. If the connections between the bases are broken, the two chains unwind and free nucleotides within the cell bind to the exposed bases of the now-separated chains. The free nucleotides align along each chain in accordance with the base-pairing rule: A binds to T, C bonds to G. This procedure produces two identical DNA molecules from a single original and is the technique through which hereditary information is transferred from one cell generation to the next.
Dystrophin
- Dystrophin is a rod-shaped cytoplasmic protein that is an essential component of a protein complex that connects a muscle fiber’s cytoskeleton to the surrounding extracellular matrix via the cell membrane. This complex is also known as the dystrophin-associated protein complex or the costamere complex (DAPC).
- At the costamere, many muscle proteins, including -dystrobrevin, syncoilin, synemin, sarcoglycan, dystroglycan, and sarcospan, colocalize with dystrophin. Its molecular weight is 427 kDa.
- Dystrophin is encoded by the DMD gene, which spans 2.4 megabases (0.08 percent of the human genome) and is located at locus Xp21. The main transcript in muscle is approximately 2,100 kilobases in length and takes 16 hours to transcribe; mature mRNA is 14.0 kilobases in length. A protein with 3685 amino acid residues is encoded by the 79-exon muscle transcript.
- Mutations in the dystrophin gene, whether spontaneous or hereditary, can result in various kinds of muscular dystrophy, a disease marked by progressive muscle wastage. Duchenne muscular dystrophy is the most frequent of these illnesses caused by hereditary dystrophin abnormalities.
Chromosome
- The microscopic threadlike structure of the cell that contains genetic information in the form of genes. A chromosome’s compactness is a defining characteristic. For example, the 46 chromosomes found in human cells have a total length of 200 nm (1 nm = 10 9 metre); if the chromosomes were unravelled, the genetic material contained therein would measure approximately 2 metres (about 6.5 feet).
- The compactness of chromosomes is critical for organising genetic material during cell division and allowing it to fit inside structures such as the nucleus of a cell, which has an average diameter of about 5 to 10 m (1 m = 0.001 mm, or 0.000039 inch), or the polygonal head of a virus particle, which may have a diameter of only 20 to 30 nm.
- The shape and placement of chromosomes distinguish viruses from prokaryotes and eukaryotes. Nonliving viruses have chromosomes made of either DNA (deoxyribonucleic acid) or RNA (ribonucleic acid); this material is packed extremely tightly inside the viral head.
- Chromosomes are fully composed of DNA in prokaryotic organisms (bacteria and blue-green algae). A prokaryotic cell’s single chromosome is not encased in a nuclear membrane.
- The chromosomes of eukaryotes are housed within a membrane-bound cell nucleus. A eukaryotic cell’s chromosomes are essentially composed of DNA coupled to a protein core. Additionally, they include RNA. This article will discuss eukaryotic chromosomes in further detail.
- Each eukaryotic species has a unique number of chromosomes (chromosome number). In asexually reproducing species, the chromosome number is identical in all of the organism’s cells.
- The number of chromosomes in the body (somatic) cells of sexually reproducing animals is diploid (2n; a pair of each chromosome), which is double the haploid (1n) number found in the sex cells, or gametes. Meiosis produces the haploid number. Two gametes join during fertilisation to form a zygote, a single cell with a diploid set of chromosomes.
- Somatic cells proliferate through a process known as mitosis. Between cell divisions, chromosomes are uncoiled, resulting in a dispersed mass of genetic material called chromatin. The uncoiling of the chromosomes initiates DNA synthesis. DNA repeats itself during this phase in preparation for cell division.
Conclusion
A gene is the smallest observable unit of heredity. Genes are built from DNA. Some genes direct the creation of proteins. However, many genes do not code for proteins. Human genome size ranges from a few hundred DNA bases to over 2 million DNA bases. The Human Genome Project, an international collaborative research effort to find the sequence of the human genome and identify genes, predicted that humans had between 20,000 and 25,000 genes. Chromosomes contain the fundamental genetic material DNA, which is responsible for conferring hereditary features and genetic information on numerous cells. Cellular activities are critical for living creatures’ growth and survival. When it comes to the chemical composition of chromosomes, they are protected from chemical enzymes and physical forces by histones and other proteins. This provides protection for DNA during cell division.