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Location of DNA in cells

1. Body cells: Human body cells contain chromosomes. DNA is located in chromosomes. Human cells have a diploid number of chromosomes.
2. Germ cells: Human germ cells contain haploid chromosomes. Haploid chromosomes contain DNA. Chromosomes in human reproductive cells are called sex chromosomes.
3. Blood: Blood is a liquid connective tissue. DNA test is done by blood test.
4. Semen: Semen of animals contains DNA. DNA is detected from semen.
5. Saliva: Human saliva contains DNA. DNA was identified from saliva.
6. Oral Fluid: Human sneezes, coughs and spit contain DNA. DNA is identified from these fluids.
7. Bone: Bone is a hard connective tissue. This connecting banana contains DNA.
8. Hair: DNA is detected from hair.
9. Fingernails: DNA is detected from fingernails and toenails.

Genome sequencing methods

Two methods of genome sequencing are – Chemical degradation method and Chain termination method. In 1976 A. Maxam I W. Gilbert Chemical degradation method and in 1977 F. Sanger I A.R. Coulsor invented the chain termination method. Genome sequencing process is described as-
1. DNA molecules are divided into 4 test tubes enriched with reagents.
2. Each of the four reactions is separated by gel electrophoresis.
3. Genome sequencing is determined from the location and size of radioactive bands.
4. The results of electrophoresis are analyzed and interpreted using a computer aided X-ray scanner.

Discovery of Genome Sequencing

The German botanist Hans Winkler (Hans Winkler, 1920) first used the term genome. The first complete genome sequencing of MS-2 virus was performed in 1976. In 1977, Dr. F. Sanger pioneered the sequencing of DNA and was the first organism to determine the genome sequence of bacteriophage. In 2020, French scientist Emmanuel Carpenter and American scientist Jennifer A. Doudana was awarded the Nobel Prize in Chemistry. Their technology is called Crisper Case Nile Genetic Scissors.

The specific order of nucleotides in a DNA molecule is called sequence. The process of determining the nucleotide or sequence of DNA is called genome sequencing. Bangladeshi scientist Dr. Maqsudul Alam and his collaborators have unraveled the genome sequencing of Tosha Pat. 12 crores of base pairs of jute. The genome of Paris japonica is the longest in the plant world. It consists of 150 billion base pairs. The genetic information of one of its cells is 328 feet long. Professor Dr. Muhammad Nurul Islam and his colleagues completed genome sequencing of mung bean yellow mosaic virus using RNAi method. The promoter of genome sequencing is Dr. Sanger (Dr. F. Sanger).

What is Genome Sequencing?

A set of chromosomes is called a genome. Human cells have a pair of genomes. Simply put, the collection of genes located in an organism is called the genome. The genome is called the master blue-print of the cell. All genes in the human genome contain about three million base pairs.

DNA Finger Print : Definition, discovery, method and importance

Fingerprints, marks or marks on human hands are called tip signatures or finger prints. Identification of specific bands from highly variable regions of DNA with radioactive probes is called DNA fingerprinting. The complex process by which an individual can be distinguished from other individuals in genetic information by determining the arrangement of deoxyribonucleotides in DNA is called DNA fingerprinting. Due to variations in DNA (ATGC), every person in the world has a different fingerprint. Fingerprints are required for land registry, marriage certificate registry, biometric seam registration, school attendance confirmation, office staff attendance confirmation, any contract etc.

Discovery of DNA finger print

In 1985 scientist Alec Jeffreys discovered the finger printing method. In 1986 this method was adopted separately.

Collection of samples for DNA fingerprinting

Blood cells (WBC), semen, bone marrow, hair follicles, skin, nails, sputum, saliva, body parts etc. are collected as samples. These cells act as a source of DNA fingerprinting. DNA finger printing requires 1 microgram of banana.

DNA finger print method

Making a photographic pattern of an organism’s DNA in the process of gel electrophoresis is called a DNA finger print or DNA profile. DNA is collected and fragments are cut by restriction enzymes. In the gel electrophoresis process, particles are run over a gel layer. The cysts become progressively smaller and accumulate as aligned bands. Photographic patterns or impressions are obtained from the bands. It is called DNA fingerprint.

Importance of DNA Finger Print

Any criminal can be reliably identified through DNA fingerprinting.
DNA finger printing is very effective in identifying murderers, rapists, robbers etc.
Paternity of the child is determined by DNA finger printing.
Relationships between close relatives are determined through DNA fingerprinting.
Genetic databanks and land registries are done with this method.

DNA fingerprinting is better than dermal fingerprinting

Individuals and criminals can be identified by cutaneous fingerprinting or dermatoglyphics. Skin fingerprinting can be changed through plastic surgery. So this method is systematic. But DNA fingerprinting cannot be changed in any way. The DNA fingerprint of any cell, organ or organ in a person’s body is always the same. So DNA finger printing is best in criminal identification.

(রাজশাহী বিশ্ববিদ্যালয়, বাংলাদেশ)

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Dr. Abu Bakkar Siddiq (Ph. D)

Dr. Md. Abu Bakkar Siddiq

BSc Honors (first class), MSc (first class), M. Phil, Ph. D

(Rajshahi University, Bangladesh)

Best Teacher and Gold Medalist-2011, 2012 and 2013

Writer, Researcher and Teacher

Birshrestha Munshi Abdur Rouf Public College

BGB Head Quater

Peelkhana

Dhaka

Bangladesh.

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