karyotypeee

[joelle]

Why would the chromosomes of a gamete not be used to produce a karyotype?

[ecoli]

Is this a homework question?

 

Think about what's different about the chromosomes in gametes and the chromosomes in somatic cells?

[joelle]

i wrote this..

Chromosomes of a gamete would not be used to produce a karyotype because they do not show homologus pairs which are needed to show different traits that an individual has. Examples of these traits include: eye colour, and height. They also do not show the sex of an individual (unless the chromosome shown is Y then it is a male) because one sex chromosome comes from the mother and one comes from the father. Somatic cells on the other hand show homologus pairs of chromosomes.

[ecoli]

You can't really see traits on the chromosomes... but you are essentially right. The purpose of the karyotype is to pair up homologous chromosomes that where obtained from each parent. In a gamete cell, meiosis only has half the number of chromosomes of a somatic cell, and therefore wouldn't be of much use in a karyotype. And yes, unless you had a y chromosome, the gender would not be known.

[Revenged]

heterogenity is the important point... for example if Mr X had was heterogenous and had Aa... you would either have 'A' or 'a' in a gamete cells... and so you wouldn't be able to tell traits from chromosomes of gamates...

 

another small point joelle... height is a bad example when talking about genetics... growth rate is basically endocrinology... growth hormone is mainly under the control of GHRH and somatostatin production from the hypothalamus... It's levels changes rapidly changes throughout the day and just about everything effects it's rate of production... Other hormones such as oestrogen have very important roles as it prevents growth of bones after purberty... Hormones produce hundreds of intracellular changes to cells, e.g. production of IGF-1 by the liver in responce to GH, which have multiple effects that lead to cellular growth, which causes an increase in height over a period of ~18 years... And of course growth rate is largely effected by nutrition and multiple other factors... All in all, you shouldn't consider growth as genetically determined... There is far more to it than tall people tend to have tall children therefore must have inherited 'tall' genes...

[joelle]

tru tru