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Karyotyping

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Published in: Biology | Biomedical Science
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This presentation is about karyotyping and its applications which is an important method in genetics.

Shradha M / Dubai

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Qualification: Bachelors in Biotechnology

Teaches: Personality Development, Science Projects, Biology, Microbiology, Physiology, Biochemistry, Pharmacology, Molecular Biology, Operational Research, Pathology, NEET, Chemistry, Psychology, Science, Social Studies, Environmental Science, Exam Preparation

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  1. Ka ryotyping By Shradha Menon
  2. Objectives To understand what is a karyotype, its purpose and applications To understand how a karyotype is made To briefly look upon types and examples of karyotypes To understand the advantages and disadvantages of karyotyping
  3. What is a karyotype? "A set of photographed, banded chromosomes arranged in order from largest to smallest" OR "The entire set of chromosomes is called the karyotype, which is studied during cell division at the moment when DNA has been duplicated" OR "A laboratory-produced image of a person's chromosomes isolated from an individual cell and arranged in numerical order"
  4. Who discovered karyotyping? • Lev Delaunay in 1922 seems to have been the first person to define the karyotype as the phenotypic appearance of the somatic chromosomes, in contrast to their genic contents.
  5. What is the purpose of karyotype? A karyotype test looks at the size, shape, and number of your chromosomes. The size of the chromosomes, the position of the centromeres, and the pattern of the stained bands can be determined from a karyotype. A chromosomal karyotype is used to detect chromosomal abnormalities and thus used to diagnose genetic diseases, some birth defects, and certain disorders of the blood or lymphatic system.
  6. How is a karyotype made? To make a karyotype, scientists take a picture of the chromosome from one cell, cut them out, and arrange them using size, banding pattern, and centromere position as guides. https://learn-eenetics.b- cdn.net/basics/karvotvpe/karvotvpe paper.pdf A computer scans the ruptured cells in a drop of stain and selects one in which the chromosomes are the most visible and well-spread. Then image analysis software recognizes the band patterns of each stained chromosome pair, sorts the structures into a size-ordered chart, and prints the karyotype. • If the software recognizes an abnormal band pattern, a database pulls out identical or similar karyotypes from records of other patients.
  7. t. Viewing chromosomes, then and now: (a) The earliest drawings of chromosomes, by German biologist Walther Flemming, date from 1882. His depiction captures the random distribution of chromosomes as they splash down on a slide (top right ) (b) A micrograph of actual stained human chromosomes (bottom right)
  8. Steps during a karyotype test 2. 3. 4. 5. 6. Taking a sample of a person's cells, culturing them in nutrient-enriched media to promote cell division in Wtro. This is done in order to select a specific time during the cells' growth phase when the chromosomes are easiest to distinguish. Isolating the chromosomes from the nucleus of the cells, placing them on a slide, and treating them with a special stain. Taking microphotographs of the chromosomes. In jigsaw puzzle fashion, rearranging the pictures of the chromosomes to match up pairs and arrange them by size, from largest to smallest, numbers 1 to 22, followed by the sex chromosomes as the 23rd pair. The pictures also allow the chromosomes to be vertically oriented. Each chromosome looks like a striped straw. It has two arms that differ in length (a short arm (p) and a long arm (q)), a pinched-in area between the arms called a centromere, and a series of light and dark horizontal bands. The length of the arms and the location of the bands help determine top from bottom. Once the chromosome photo arrangement is completed, a laboratory specialist evaluates the chromosome pairs and identifies any abnormalities that may be present.
  9. BASIC STRUCTURE OF A CHROMOSOME Telomere Short arm Centromere Longer arm ister chromatid Chromosome
  10. Different types of chromosomes seen in a karyotype 4 types of chromosomes are: I. Acrocentric chrornosomes: These are chromosomes whose centromere present near the end of chromosomes. It forms a very short p arm and a very long q E.g. 13th, 14th, 15th, 21st, 22nd, and Y chromosomes are acrocentric in humans. 2. Sub metacentric chromosomes: These are chromosomes whose centromere is present near the middle and divides the chromosome into two unequal arms. It is an L•shaped chromosome. Most chromosomes in humans are submetacentric, E.g. 2nd, 4th to 12th, 17th, 18th and X chromosomes. 3. Metacentric chromosomes: These are chromosomes whose centromere separates the chromosome into two equally sized arms and is located in the center of each one. The metacentric chromosome is shaped like an X _ E.g. In, 3rd, 16th, and 20th are metacentric chromosomes in humans. 4. Telocentric chrornosomes: These are chromosomes that have centromeres present at the end of the chromosome. It is not observed in humans. The shorter p arm is barely visible. The shape of the chromosome at the anaphase is like the letter
  11. Secondary constriction Short arm Centromere Long arm Short arm Centromere Satellite Centromere Acrocentric Submetacentric Metacentric Telocentric Chromosome showing satellite region Types Of chromosomes
  12. Types of karyotypes 01 Symmetrical- The karyotype in which the size of chromosomes is approximately the same and has a centromere located at the center. 02 Asymmetrical- The karyotype represents different shapes of chromosomes. It is the most advanced Karyotype which shows few metacentric and more acrocentric chromosomes.
  13. General applications of karyotyping Karyotypes can be used for many purposes; such as to study chromosomal aberrations, cellular function, taxonomic relationships, medicine and to gather information about past evolutionary events (karyosystematics).
  14. Applications of karyotyping in human genetics A chromosomal karyotvpe is used to detect chromosome abnormalities and thus used to diagnose genetic diseases, some birth defects, and certain disorders of the blood or lymphatic system. It may be performed for: A fetus, using amniotic fluid or chorionic Villi (tissue from the placenta): If one or more of a woman's pregnancy screening tests, such as the first trimester Down syndrome screen or the second trimester maternal serum screening, are abnormal. If a pregnant woman is having amniotic fluid analysis performed because she is considered at higher than normal risk of having a baby with a birth defect. If fetal structural and/or developmental abnormalities are detected, such as during an ultrasound. If there is a known chromosomal abnormality in the family line. A woman or a couple, prior to pregnanc•,', to evaluate her or their chromosomes, especially if a woman has experienced previous miscarriages or infertility. Tissue from a miscarriage or stillbirth, to help determine if the cause was due to a chromosomal abnormality in the fetus. An infant who is born with congenital abnormalities, including physical birth defects, mental retardation, delayed growth and development, or signs of a specific genetic disorder. A person with infertility or one who shows signs of a genetic disorder. Family members, to detect specific chromosomal abnormalities when they have been detected in a child or another family member. A person who has been diagnosed with certain types of leukemia, lymphoma, refractory anemia, or cancer as these conditions can lead to acquired changes in chromosomes; this testing may be performed on blood or a bone marrow sample.
  15. Types of chromosomal abnormalities detected by karyotype analysis Trisomy Deletions Duplications Translocations Genetic Rearra ngement This is the presence of an extra chromosome, a third instead of a pair. Diseases associated with trisomies include Down syndrome (associated with a Trisomy Of chromosome 21), Patau syndrome (Trisomy 13), Edward syndrome (Trisomy 18), and Klinefelter syndrome (a male with an extra X chromosome - XXV instead of XY). This is the absence of one of the chromosomes. An example of monosomy is Turner syndrome (a female with a single X chromosome - X instead Of XX). Most Other monosomies are not compatible with life. These are missing pieces of chromosomes and/or genetic material. Some may be small and difficult to be detected. These represent extra genetic material and may be present on any chromosome, such as the presence Of two horizontal bands at a specific location instead of one. With translocations, pieces Of Chromosomes break Off and reattach to another Chromosome. If it is a one-to-one switch and all Of the genetic material is present (but in the wrong place), it is said to be a balanced translocation. If it is not, then it is called an unbalanced translocation. With this, genetic material is present on a chromosome but not in its usual location. A person could have both rearrangement and duplication or deletion. An almost infinite number of rearrangements are possible. Interpreting the affects of the changes can be challenging.
  16. Examples of karyotypes 1. Normal male (46, XY) if 15 10 16 11 17 12 18 19 14 20
  17. Examples of karyotypes 2. Normal female (46, XX) 14 19 Karyotgpe : 46 , 11 17 21
  18. Examples of karyotypes 3. Down's syndrome (47,XX/XY +21) Down Syndrome - Trisomy 21 47,xy..2t TRISCNY 2' (OOWuS SYNDROME) 2 8 19 20 21 22 XX xy
  19. Examples of karyotypes 4. Turner's syndrome (45, XO) Turner syndrome karyotype 10 16 17 11 18 12 19 14 20 15 21
  20. Limitations of karyotype testing 01 It's important to note that while karyotype testing can give a lot of information on chromosomes, this test cannot tell you whether specific gene mutations, such as those which cause cystic fibrosis, are present. 02 Also, at times karyotype testing may not be able to detect some chromosomal abnormalities, such as when placental mosaicism is present.
  21. REFERENCES 30 Seconds Genetics book by Jonathan and Matthew Weitzman 'What is a Chromosome draw a labeled diagram of the class 12 biology CBSE' (no date). Available at: httos: / ntu com/auestion-answer/a-chromosome-draw-a-labeled-diagram-of-the-cIa5s-12-bioIogy-cbse- Sfd8c6S8d7db7boggsd9763d. Karyotype. (2022, October 7). In Wikipedia. https://enwikipedia.org/wiki/karvotvpe 'What are the 4 types Of chromosomes?' (no date). Available at: https://byius.com/question-answer/what-are-the-a-types-of- chromosomes'. 'Karyotypes I Biology - Quizizz' (no date). Available at: htt05://auizizz.com/admin/auiz/5dagd5daaSOc8dOOIafa2d51/karvotypes. 'What are the two types Of karyotypes?' (no date). Available at: https://bvius.com/question-answer/what-are-the-two-tvpes-of- karvotvpes/. 'Chromosome Ana ys"s (Karyotyping) I Labcorp' (no date). Available at: httos://wwwlabcorp.com/help/oatient-test- info/chromosome-analysis-karyotyping 'The Purpose and Steps Involved in a Karyotype Test' (no date). Available at: https://wmv.vervwellhealth.com/how-to-how-is-a- karyotvpe-test-done-1120402.

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