Still catching up! Days 26 - 28. See
Hope for Trisomy for more educational posts!
Day 26: Dicentric Chromosome
On our 26th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share about a STRUCTURAL ABNORMALITY that we have not mentioned before. A DICENTRIC CHROMOSOME is the result of a rearrangement that places two centromeres on the same chromosome. The interaction of radiation with these chromosomes causes the break and then it becomes unstable, which often involves a loss of some genetic material. The formation of a dicentric chromosome is highly specific to ionizing radiation and its frequency serves as a measure of radiation exposure received by a person. In the event of higher exposure to radiation, such breaks may occur in more than one chromosome. Share because you Care. ♥
Day 27: Metacentric, Submetacentric, Acrocentric, and Telocentric Centromere Positions
On our 27th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share about four types of chromosomes based on the position of the centromere. The four types are Metacentric, Submetacentric, Acrocentric, and Telocentric. Metacentric is a type of chromosome having two equal arms because the centromere is in the median position. Submetacentric is a type of chromosome where the centromere is slightly away from the centre and therefore chromatids of one side are a little longer than the other side. Acrocentric is a type of chromosome where the centromere is located closer to one end and therefore the chromatids on the opposite side are very long. The small round structure is referred to as a satellite, and the thin strands at the satellite region are termed the Nucleolar Organiser Region. Telocentric is a type of chromosome where the centromere is placed at one end of the chromatid, hence only one arm. The telocentric chromosomes are not seen in human cells. Share because you Care. ♥
Day 28: Autosomes and Allosomes
On our 28th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share about the chromosome types that are divided into two categories, those being the AUTOSOMES and ALLOSOMES. AUTOSOMES are the structures that contain the hereditary information. They do not contain the information related to reproduction and sex determination. Autosomes are identical in both male and females. The human body contains 22 pairs of autosomes. An ALLOSOME is a sex chromosome that differs from an ordinary autosome in form, size, or behavior. The X chromosomes are present in the ovum and either the X or Y chromosome can be present in the sperm. If the offspring receives one X chromosome from the mother as well as father, it results in a female child (XX). If the offspring receives one X chromosome from the mother and one Y chromosome from the father, it results in a male child (XY). It is the donation of the X or Y chromosome by the father that determines the sex of the offspring. Since only males have a Y chromosome, then there must be a gene that makes the individual a male. Scientists have identified and isolated this gene and have termed it the SRY gene. Interestingly enough, this gene does not activate until 6 weeks after conception. Once activated, female structures are destroyed and the individual develops as a male. Share because you Care. ♥
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