The Karyotype - Life Science Textbook PDF

Life Science The Karyotype Chapter 2 – Activity 1 sic nd ba a e ife ad -L gr ook b...

Life Science The Karyotype Chapter 2 – Activity 1 sic nd ba a e ife ad -L gr ook b Grade : Secondary Education – - 9 xt es te th io nc al Second Year at ie on uc sc ati ed rth - N n ea DP Section : Sciences CR Part : 1 Topics 1 Karyotype Definition. 2 Steps of Karyotyping. 3 Male and Female Somatic Karyotype. 4 Sex Chromosomes for Sex Determination. 5 Chromosome Number in Some Species. Cell renewal in living things is achieved through specialized cells that are capable of division and differentiation while keeping their genetic characteristics because of chromosomes present in each cell. What is the technique for viewing and studying chromosomes? https://www.researchgate.net/figure/Images-from-chromosomes-in-the- metaphase-stage_fig1_344213885 Grade : Second Secondary Year/ Part 1/ Section: Sciences  DEFINITION OF KARYOTYPE Document 1 represents the karyotype of a human individual. The karyotype is a representation of all of the chromosomes in a cell classified according to well-defined criteria. The karyotype can be used to study the number and structure of chromosomes, to identify chromosomal abnormalities and to differentiate chromosomes of different species. Karyotyping procedure is a process of preparing, arranging and categorizing chromosomes of a cell. This technique requires the observation of chromosomes during a well-defined period of cell Document 1 http://www.jpb-imagine.com/Sharjah/ 3_C4_2016/32genevol/doc32/Chap1/ division. Chap114.html What are the steps to prepare a human karyotype? Grade : Second Secondary Year/ Part 1/ Section: Sciences  STEPS OF KARYOTYPING PROCEDURE Step 2 Step 1 Step 3 Step 4 Step 9 Step 5 What is the purpose of each step? Step 8 Step 6 CRDP- National Textbook-Life Science- Second secondary year—Sciences section. Step 7 Grade : Second Secondary Year/ Part 1/ Section: Sciences STEPS OF KARYOTYPING PROCEDURE Step 1 Cell Collection A blood sample is collected to obtain nucleated cells, white blood cells. Nucleated cells can be taken from different tissues including bone marrow, amniotic fluid, or placenta. 1- Justify why human red blood cells are not suitable for karyotyping. Human red blood cells are not suitable for karyotyping since they are not nucleated, so they don’t have chromosomes. Grade : Second Secondary Year/ Part 1/ Section: Sciences STEPS OF KARYOTYPING PROCEDURE Step 2 Cell Culture The sample of cells removed from the blood is placed in a convenient culture medium in which white blood cells will grow and multiply. Step 3 Metaphase Blocking Grade : Second Secondary Year/ Part 1/ Section: Sciences  STEPS OF KARYOTYPING PROCEDURE Step 4 Hypotonic Solution The cells blocked at metaphase are put in a hypotonic solution to ensure the swelling and bursting of the cells and consequently their chromosomes spread out. Step 5 Spreading the Chromosomes Cellular constituents are spread on a slide to obtain clusters of chromosomes Grade : Second Secondary Year/ Part 1/ Section: Sciences STEPS OF KARYOTYPING PROCEDURE Step 6 Staining Fix the preparation and stain it to visualize the bands of chromosomes. Step 7 Microscopic Observation The preparation is observed under a microscope equipped with a camera. Nowadays, the observation is done directly on a computer screen. Grade : Second Secondary Year/ Part 1/ Section: Sciences STEPS OF KARYOTYPING PROCEDURE Step 8 Microphotograph y Take pictures of metaphase chromosomes. Step 9 Cutting Out and Arrangement The photograph of the chromosomes is cut up and arranged according to well-defined criteria. Grade : Second Secondary Year/ Part 1/ Section: Sciences  STEPS OF KARYOTYPING PROCEDURE 2- Draw out, based on the given in document 2, the criteria for the arrangement of chromosomes during the last step of karyotyping procedure. Chromosomes are arranged : in pairs of homologous chromosomes of the same size, same position of the centromere and same banding pattern. in a decreasing order of size. The 22 pairs of autosomes (non-sex chromosomes) are numbered from 1 to 22 and the 23rd pair of the sex http://www.jpb-imagine.com/Sharjah/ chromosomes or gonosomes are set Document 2 3_C4_2016/32genevol/doc32/Chap1/ Chap114.html aside the autosomes. Grade : Second Secondary Year/ Part 1/ Section: Sciences  SEX CHROMOSOMES DETERMINE THE SEX Document 3 represents the karyotype of skin cells for two individuals A and 3- B. Compare the karyotypes of both individuals. Both karyotypes contain the same A number of chromosomes (46 or 23 pairs of chromosomes), of autosomes (44 or 22 pairs of homologous CRDP- National textbook- Life autosomes) and of sex chromosomes and earth sciences- 9 th grade basic (2Specify 4- or 1 pair theof Homologous sex of each of (A) the non education homologous individuals(B) A chromosomes). and B. Individual A is female because the sex chromosomes present in her karyotype B are XX, and B is male since his karyotype reveals the presence of the sex chromosome Y. Document 3 Grade : Second Secondary Year/ Part 1/ Section: Sciences  CHROMOSOME NUMBER IN SOME SPECIES The number of chromosomes is generally characteristic of the Animals Number of Plants Number of species. Some species may have chromosomes chromosome s the same number of chromosomes, Mouse 40 Pea 14 but they are different (document Rat 42 onion 16 4). 5- Formulate a hypothesis that Rhesus monkey 42 corn 20 explains the difference Man 46 Tomato 24 between species that have Chimpanzee 48 Rice 24 the same number of Dog 78 Tobacco 48 chromosomes. Hen 78 Potato 48 Hypothesis: the genetic Document 4 information carried by the chromosomes is not the same in species that have the same number of chromosomes. Grade : Second Secondary Year/ Part 1/ Section: Sciences  ? End of Lesson Questions 1 During the 16th week of pregnancy, Mrs. X was subjected to an ultrasound. The gynecologist has detected that the thickness of the neck of her fetus is not normal. Faced with this problem, he prescribed an amniocentesis to perform the karyotype of the fetus. The steps of this Document 1 S. Gaujean -CC-NC-SA 2.0, ressource technique are shown in éduthèque & V. Guili http://www2.ac- lyon.fr document 1.  ? End of Lesson Questions 1 Document 1 shows the steps of karyotype preparation. 1.List the missing steps - Cells blocked at metaphase are put in hypotonic solution. - Chromosomes are stained with a dye. Document 1 Grade : Second Secondary Year/ Part 1/ Section: Sciences  ? End of Lesson Questions 1 Document 2 represents the karyotype of the fetus of Mrs. X : 2. Specify the sex of the fetus. The fetus is male since his karyotype reveals the presence of the gonosome Y. 3. Verify if the karyotype of the fetus is normal or not. The karyotype of the fetus is not normal because it shows the presence of 47 Document 2 httpmedgen.unige.chc chromosomes instead of 46 including one extra ytogeneticsphotosresu ltats5.jpg chromosome no21 ( three chromosomes 21 4. instead of two). Draw out the importance of performing a karyotype. In addition to its role in the identification and differentiation of chromosomes in different species, the karyotype can detect chromosomal abnormalities, especially during prenatal Grade : Second Secondary Year/ Part 1/ Section: Sciences References D DD D D https://www.researchgate.net/figure/Images-from-chromosomes-in-the-metaph ase-stage_fig1_344213885. http://www.jpb-imagine.com/Sharjah/3_C4_2016/32genevol/doc32/Chap1/Chap 114.html https://www2.ac-lyon.fr CRDP- National Textbook- Life Sciences-Second Secondary Year-Science Section. CRDP- National Textbook-Life and earth Sciences-9th Grade Basic Education. Our team Coordinator: Rana Abdallah Author: Rafah AL Sabbagh Reviewer: Mirna Mhana Language Editor: Mariam Hankir Translator: Sahar Ibrahim Thank You!