pottsy1000
New Member
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- Jun 2, 2005
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do u have to explain why the pedigree is used? do u have to make up 1 on ur family or just get any 1... confused
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HELP!!! please pedigrees (1 Viewer)
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danieljarvis
Member
you can say why a pedigree is used, like how gene therapists can tell you the odds of your child having whatever disease or characteristic according to you and your spouse....
but what you'll most likely get asked is to maybe cross two parents to produce an f1 generation, or cross an f1 generation to get an f2 generation.. and if they ask for your knowledge you'll need to discuss the factors of inheritance such as dominant and recessive traits, ratios of offspring and DRAW PUNNET SQUARES (grids if u may)
i think that's what you wanted to know.. so in short, YES you can quite likely be asked to write up a pedigree chart, and im not sure if you'll need to state WHY they are used.
but what you'll most likely get asked is to maybe cross two parents to produce an f1 generation, or cross an f1 generation to get an f2 generation.. and if they ask for your knowledge you'll need to discuss the factors of inheritance such as dominant and recessive traits, ratios of offspring and DRAW PUNNET SQUARES (grids if u may)
i think that's what you wanted to know.. so in short, YES you can quite likely be asked to write up a pedigree chart, and im not sure if you'll need to state WHY they are used.
pottsy1000
New Member
- Joined
- Jun 2, 2005
- Messages
- 16
thanks heaps that makes so much more sense now...
danieljarvis
Member
yeah or if it is recessive or dominant.
sory, shit ok ill try say all of the things to do with pedigrees.
they can ask if a trait is Dominant, Recessive, Co-dominant, Incomplete or Sex-Linked. By drawing a punnet square and giving you the infromation..
ways to tell if something is:
Dominant - If one parent displays the trait and all children display it. Means one parent was homozygous dominant ( RR ) and the other (homozygous , rr ) recessive.
Recessive - Both parents don't display the trait, and no children do either.
some info on:
Co-Dominant - Two parents showing different phenotypes have offspring displaying a mix of both phenotypes. E.g. Rhoan ( R1, R2 ) red and white hairs combined, colour in cows, one parent red ( R1, R1 ) , one parent white ( R2, R2 ).
Incomplete Dominance - Two parents displaying different phenotypes create offspring showing a mix of the two phenotypes. White and Red snapdragons produce pink offspring.
Sex-Linked - Trait carried on the y chromosome, 90% of cases only shows on the male offspring. Thomas Hunt Morgan (T.H.Morgan) created this theory from working with Fruit Flies ( Drosophila melanogaster ), bred them till he got a mutation ( white eyed male, instead of red eyes ) and bred this white eyed male with virgin sisters. Trait didnt show in the F1 generation, Bred this generation together and White eyes reccured in the F2 generation, only on males.
sory, shit ok ill try say all of the things to do with pedigrees.
they can ask if a trait is Dominant, Recessive, Co-dominant, Incomplete or Sex-Linked. By drawing a punnet square and giving you the infromation..
ways to tell if something is:
Dominant - If one parent displays the trait and all children display it. Means one parent was homozygous dominant ( RR ) and the other (homozygous , rr ) recessive.
Recessive - Both parents don't display the trait, and no children do either.
some info on:
Co-Dominant - Two parents showing different phenotypes have offspring displaying a mix of both phenotypes. E.g. Rhoan ( R1, R2 ) red and white hairs combined, colour in cows, one parent red ( R1, R1 ) , one parent white ( R2, R2 ).
Incomplete Dominance - Two parents displaying different phenotypes create offspring showing a mix of the two phenotypes. White and Red snapdragons produce pink offspring.
Sex-Linked - Trait carried on the y chromosome, 90% of cases only shows on the male offspring. Thomas Hunt Morgan (T.H.Morgan) created this theory from working with Fruit Flies ( Drosophila melanogaster ), bred them till he got a mutation ( white eyed male, instead of red eyes ) and bred this white eyed male with virgin sisters. Trait didnt show in the F1 generation, Bred this generation together and White eyes reccured in the F2 generation, only on males.
Sex linked inheritance is a bit confusing, but you have almost got it.
the gene/trait is carried on the X chromosome, NOT THE Y CHROMOSOME and there is no corresponding gene on the Y chromosome.
Therefore, since males have only one X chromosome (XY), the require only on allele, while females (XX) require two... (although you can have "females" with XY chromosomes) This is why more males have sex-linked characteristics such as colour blindness.
what morgan did was not breed until he got a mutation (the white eye/ red eye isnt mutation, it is just variation.. like red hair and black hair sort of) but looked at crosses between red eyed and white eyed flies and found that the results could not be accounted for by simple mendelian crosses. so he proposed sex linkage, that is some genes are carried on X chromosome.
i hope that helps!!!
good luck everyone!!
peace
the gene/trait is carried on the X chromosome, NOT THE Y CHROMOSOME and there is no corresponding gene on the Y chromosome.
Therefore, since males have only one X chromosome (XY), the require only on allele, while females (XX) require two... (although you can have "females" with XY chromosomes) This is why more males have sex-linked characteristics such as colour blindness.
what morgan did was not breed until he got a mutation (the white eye/ red eye isnt mutation, it is just variation.. like red hair and black hair sort of) but looked at crosses between red eyed and white eyed flies and found that the results could not be accounted for by simple mendelian crosses. so he proposed sex linkage, that is some genes are carried on X chromosome.
i hope that helps!!!
good luck everyone!!
peace
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danieljarvis
Member
sry x chromosome.. moment of stupidity.
and we were taught this year that he bred until he found a mutation. and our teach said that the white eyes were a mutation?
he did this expirement over 4 years i think, so i believe that white eyes is a mutation rather than just a simple variation.. and researhcing internet sites says they are red eyed, i also cant picture it taking 4 years to find a simple variation change, especialy when Drosophila melanogastor can breed every two weeks with 400 or so offspring.
and we were taught this year that he bred until he found a mutation. and our teach said that the white eyes were a mutation?
he did this expirement over 4 years i think, so i believe that white eyes is a mutation rather than just a simple variation.. and researhcing internet sites says they are red eyed, i also cant picture it taking 4 years to find a simple variation change, especialy when Drosophila melanogastor can breed every two weeks with 400 or so offspring.
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