Teratogens and Their Effects on Pre-Natal Development

Topics: Pregnancy, Down syndrome, Embryo Pages: 8 (2550 words) Published: April 25, 2013
Teratogens and their effects on pre-natal development

In this essay we will look into what teratogens are. The different types of teratogens, and how much of a role they play on the pre-natal development, and the foetus. Also how the teratogens that impacts us in the womb, can also affect our bodies and our minds for the rest of our natural lives. We shall also discuss all the different stages of pre-natal development, from the conception, to the birth, and all the different factors in the growth rate of the foetus. We will also clear up the confusion that comes from people when it comes to teratogens and genetic disorders. One common misconception is that someone who drinks and smokes during pregnancy will have more of a chance of having a person develop Down syndrome. I even thought this. But in my studies on this subject i found that, to my surprise, it is a genetic disorder. My cousin who had had Down syndrome had it because it was a chromosomal disorder. Not an environmental or self-medicated teratogen played a part on him developing trisomy 21(Down syndrome). On the other hand, environmental and self-medicated teratogens played a huge part on his foetal development and his growth rate. His mam was in her late forties when she conceived and was a heavy smoker and drinker throughout the term of her pregnancy. He died pretty young from a weak heart; this was probably due to the smoking and drinking during pregnancy.

Long before a woman goes into the process of giving birth, and even longer before the conception has happened our chromosomes and genes (DNA) have already mapped out our hereditary details in the man’s sperm and the women’s egg. Our genes are like an instruction manual for our bodies. They affect our look, our health, and how our minds work. A zygote is women’s eggs that have been fertilized by the man’s sperm. The zygote consists of 23 pairs of chromosomes: 23 singles chromosomes from the man’s sperm and 23 from the women’s egg (46 in total) each pair of chromosomes contains one chromosome from each parent. The final chromosome from each parent determines the sex of your child.O’ Brien. E.(2008).

* The males 23rd pair consists of an x and a y chromosome * The female 23rd consists of an x chromosome

Genetic conditions:
We’ve seen that each human has 23 pairs of chromosomes and at conception we inherit one chromosome from our father and one from our mother making up one pair. Genes are segments in the chromosome and are your bodies’ instruction manual. Some genes are dominant and some are recessive. The major difference between dominant and recessive gene inheritance is as follows. O’Brien,E (2008)

Recessive: for the child to inherit the condition it must inherit both variant (affected) genes from both parents. Thus a child has one in four chance of inheriting the condition, a one in two chance of becoming a healthier carrier, and one in four chance of not inheriting the infected gene what so ever. Examples of recessive patterns of inheritance are: Cystic Fibrosis, sickle cell disease, Tay Sachs, and Phenylketonuria (PKU).O’Brien, E (2008).

Dominant: one parent is affected and one is healthy. At conception if the variant gene of the effected parentis transferred the child will inherit the condition. It does not matter if the other parent’s genes are healthy. Thus with dominant conditions such as Huntington’s disease, the child has a one in two chance of inheriting the condition.O’Brien.E (2008)

Down syndrome is slightly different in that it’s a chromosomal disorder. The most common form of Down syndrome is known as Trisomy 21, a condition where individuals have 47 chromosomes in each cell instead of 46. This is caused by an error in cell division called nondisjunction, which leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception. Trisomy 21 accounts for 95% of Down syndrome cases, with 88% originating from nondisjunction of the...
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