How would you explain sexlinking to a 14 year old audience?!

[magicpigeon]

Long story short it's a biology lecturette thing - 5 minutes long and I've been "invited" to a local school with a few of my chickens

Given that I only really know the basics of sexlinking et cetera and I'm such a terrible public speaker would anyone have any words of wisdom for me?

thanks ..... i am really nervous

 

[Mac in Wisco]

The males have certain traits and the female have other traits. Knowing this we can tell the males from the females when they are chicks, which is otherwise a difficult process...

From there just discuss the different traits.

 

[Mac in Wisco]

If you want to get in depth you can talk about genes carried on the X and Y chromosomes, but 14 year olds will tune out that discussion.

 

[Mia_]

Roosters have the XX chromosome, hens have XY. The gene for color is on these chromosomes. It is called sex-linked, because the color gene is attached to the chromosome that determines the sex of the bird.

 

[thekid]

Well I would want to hear what makes them different. Like boy from girl. And how?

 

[ivan3]

Like Mac said, keep it simple (don't want to have to have the class go all `MEGO' on you as you explain Z's and W's...).

Provide this link for those who want to do further reading (good bibliography), maybe one or two will pick up on it... well, hope doesn't spring - but it still manages to crawl.

http://people.eku.edu/ritchisong/avianreproduction.html

 

[mom'sfolly]

Any fourteen year old should have had enough basic biology to know that some traits are sex-linked. In the case of chickens, it has been used for easy sex identification of young birds. The reasons why this is developed might be more interesting than the fact that it exists. Red-green colorblindness and male pattern baldness are two of the most common sex-linked traits in humans. Male pattern baldness is only expressed after puberty, but red-green colorblindness shows up before.

 

[Sonoran Silkies]

Quote:
ARRRGH!!! NO!!!

MAMMALS have X & Y chromosomes; males are XY, females XX.

BIRDS have Z & W chromosomes; males are ZZ, females ZW.

The Y and W chromosomes are shorter than their counterpart, and thus do not have all the genes contained on the counterpart. Thus, the gender with unmatched chromosomes (male mammals, female birds) have only one of certain genes, not a pair. When producing offspring, they always give that single gene to the opposite gender. Their offspring of the same gender, they give their LACK of a gene.

For a trait to be used for sex-linking, it must be obvious at hatching or very early in life. Traits that do not show up for months are not good sex-linking genes. For example, at least one of the genes that determines egg colour is sex-linked, but that is obviously not useful in determining the gender of a chick; the bird must be old enough to lay before the egg colour would determine gender, and the egg laying itself makes the determination; not to mention the many other traits that will show gender before then.

The most common genes used for sex-linked chickens are barring for black sex-links, and silver for red sex-links. The mother carries a single copy of the dominant allele (variation of the gene). The male must carry two copies of the recessive allele. Female offspring will carry one copy of the recessive allele, and males will have one copy of the dominant and one of the recessive.

 

[deerman]

Ok with out going to deep in gentics......birds and mammal are different....sex chromosomes males have two in birds , female only have one so a color or pattern that is carried on the sex chromosome, if recessive, males will not show it unless both parents carried carry one sex chromosomes with that color.

Like Albino is carry on sex choromsomes...so with birds if the male is showing albino, then both his sex chromosome carry albino, mated with a hen non-albino. male young will get a sex chromosome from each parent, albino is recessive so reason all males will be non-albino, female will only get one chormosome from father, and so each female will be albino.

Birds the father can carried albino hidden on one of the sex chormosomes, passing it to some daughters

Mammals , Like humans the mother can carry albino hidden on one her sex chormosomes , passing it to some sons

 

[Sonoran Silkies]

Quote:
Except that albino in birds (or at least chickens) is not a sex-linked gene. It's a recessive allele (actually a couple of different ones) of recessive white.

My suggestion is to read the sex-link stickey at the top of the Breeds and Genetics section. The author is (or was; I think he retired) a high school biology teacher, and is very good at giving explanations.