Karyotype_cell biology_undergraduate .pptx

Karyotype_cell biology_undergraduate

1. Karyotype

2. Karyotype is a profile of organism's chromosomes which are organized by their size, pattern and location of centromere. The order of chromosomes is done according to the size as it´s easier for specialists to find some disorders. Karyology: The study of whole sets of chromosomes is sometimes known as karyology. Karyogram : The chromosomes are depicted in a standard format known as a karyogram or ideogram . What is Karyotype?

3. Karyotype Characteristics Most of the chromosomes are paired (same length, centromere location, and banding pattern). These chromosomes are called autosomes. Humans has 22 pairs of autosomal chromosomes (numbered 1 to 22) and 1 pair of sex chromosomes (X, Y). Sex chromosomes, the X and the Y do not look alike. The karyotypes for female contains two X chromosomes and are denoted as XX. The karyotypes for male contains both X and Y chromosomes and are denoted as XY. Any variation from the standard karyotype may lead to developmental abnormalities.

4. Abnormal Human Karyotype Normal karyotype of human is 46 but various types of chromosomal abnormalities either in their number or morphology have been observed. These chromosomal abnormalities are expressed in a defective phenotype i.e. various defects in the morphology and physiology. The chromosomal abnormalities can be studied majorly in two types- Autosomal Abnormalities Sex Chromosome Abnormalities

5. Autosomal Abnormalities

6. Sex Chromosome Abnormalities

7. Detection of chromosomal abnormalities Genetic disorders Gender identification Identify loss and addition of chromosome Pre-birth diagnosis of genetic diseases Identification of chromosomal numbers in different organism Identification of proper position of genes in chromosomes Advantages of Karyotype

8. Disadvantages of Karyotype Very small abnormality cannot be shown by karyotyping. Technique only allows for diagnosis and not a cure The test like amniocentesis and chorionic villus sampling ( CVS) are both risky and stressful for mother Time consuming process A minor mistake in a process will change all the result.

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10. Polyploidy vs Aneuploidy Aneuploidy is a chromosomal mutation in which there is one or more extra chromosomes, or one or more fewer chromosomes. In humans, the genetic disorders Down syndrome and Turner's syndrome are examples of aneuploidy. Individuals with Down syndrome have three copies of chromosome 21, so their genomes contain 47 chromosomes rather than the usual 46. Individuals with Turner syndrome have only one sex chromosome, which is the X-chromosome, so their genomes contain 45 chromosomes. Polyploidy is a chromosomal mutation in which a cell has entire extra sets of chromosomes. Instead of being diploid, in which the cell contains two sets of chromosomes, it may be triploid (three sets of chromosomes), or tetraploid (four sets of chromosomes). Polyploidy is common in plants, and plant growers may exploit this fact to produce plants with flowers having double petals. Polyploidy is generally lethal in animals.

11. Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21. Symptoms include a varying degree of mental retardation, growth failure, muscular hypotoicity , flay occiput, large tongue, slanting eyes, simian palmar crease, intestinal and heart problems, and acute leukaemia . Older survivors often develop Alzheimer's disease in their fourth or fifth decade. The syndrome is associated with advanced maternal age.

12. Klinefelter syndrome Klinefelter syndrome is a chromosomal condition in boys and men that can affect physical and intellectual development. Most commonly, affected individuals are taller than average and infertile; however the signs and symptoms of Klinefelter syndrome vary among boys and men with this condition. In some cases, the features of the condition are so mild that the condition is not diagnosed until puberty or adulthood, and researchers believe that up to 75 percent of affected men and boys are never diagnosed. Boys and men with Klinefelter syndrome typically have small testes that produce a reduced amount of testosterone (primary testicular insufficiency). Testosterone is the hormone that directs male sexual development before birth and during puberty. Without treatment, the shortage of testosterone can lead to delayed or incomplete puberty, breast enlargement (gynecomastia), decreased muscle mass, decreased bone density, and a reduced amount of facial and body hair.

13. Other differences can include abnormal fusion of certain bones in the forearm (radioulnar synostosis), curved pinky fingers (fifth finger clinodactyly), and flat feet. Children with Klinefelter syndrome may have low muscle tone (hypotonia) and problems with coordination that may delay the development of motor skills, such as sitting, standing, and walking. Affected boys often have learning disabilities, resulting in mild delays in speech and language development and problems with reading. Boys and men with Klinefelter syndrome tend to have better receptive language skills (the ability to understand speech) than expressive language skills (vocabulary and the production of speech) and may have difficulty communicating and expressing themselves. Individuals with Klinefelter syndrome tend to have anxiety, depression, impaired social skills, behavioral problems such as emotional immaturity and impulsivity, attention-deficit/hyperactivity disorder (ADHD), and limited problem-solving skills (executive functioning). About 10 percent of boys and men with Klinefelter syndrome have autism spectrum disorder. Nearly half of all men with Klinefelter syndrome develop metabolic syndrome, which is a group of conditions that include type 2 diabetes, high blood pressure (hypertension), increased belly fat, high levels of fats (lipids) such as cholesterol and triglycerides in the blood.

14. Turner syndrome Turner syndrome is a chromosomal condition that affects development in females. The most common feature of Turner syndrome is short stature, which becomes evident by about age 5. An early loss of ovarian function (ovarian hypofunction or premature ovarian failure) is also very common. The ovaries develop normally at first, but egg cells (oocytes) usually die prematurely and most ovarian tissue degenerates before birth. Many affected girls do not undergo puberty unless they receive hormone therapy, and most are unable to conceive (infertile). A small percentage of females with Turner syndrome retain normal ovarian function through young adulthood.

15. About 30 percent of females with Turner syndrome have extra folds of skin on the neck (webbed neck), a low hairline at the back of the neck, puffiness or swelling (lymphedema) of the hands and feet, skeletal abnormalities, or kidney problems. One third to one half of individuals with Turner syndrome are born with a heart defect, such as a narrowing of the large artery leaving the heart (coarctation of the aorta) or abnormalities of the valve that connects the aorta with the heart (the aortic valve). Complications associated with these heart defects can be life-threatening. Most girls and women with Turner syndrome have normal intelligence. Developmental delays, nonverbal learning disabilities, and behavioral problems are possible, although these characteristics vary among affected individuals.