It's over!

[fdsfsgdfgdf]

the question says the that patient X had a daughter what dyre would appear ... red or green or black?

[10weid]

Anyone care to give a rough outline of how this question went? I think people are confusing genetic pre-disposition to genetic causation.

it said that patient X suffers breats cancer, mutation on p53 allele, she has a single mutant allele and a sdingle normal allele.
asks if it would be expected that her daughter would present with a mutant allele of a normal allele.

logically, seemed like somatic mutation not germline so inferred duaghter would express normal allele onlyy?

I'm confused. Did she inherit this mutation on the p53 allele, or did it occur spontaneously? If she inherited it, there's a 50% chance her daughter will get it too. If she had it spontaneously, then it won't be passed on to her daughter.

haha dudee i was paraphrasing for ease of interpretation...asks essentially whether daughter would hav mutant allele or normal allele (determingin colour of dye schmuck)..
didnt mention whther muation was spontaneous, however strongly suggested that it was a subsitiution point mutation so i guess somaticc ?

[mandy]

I thought it wasnt too bad. Got it all done and I think only really made a few mistakes. Stupidly read the electrophoresis question wrong. Didnt realise that the band was above the well and so i wrote that the technician didnt use the restriction enzyme. But other than that I reckon that I got most questions alright without too many stupid mistakes

I also wrote that the technician forgot to use restriction enzymes.

For the qn where we had to draw a plasmid, I just drew a circle. Whats it really meant to look like?
And, for that cow qn, wheere we had to draw the band thing on the gel electrophoresis, where was it meant to go?

[shinny]

I STUFFED THAT QUESTION UP -- THE DAUGHTER CANNOT GET IT CUZ THE MUTATION WAS IN A SOMATIC CELL   :tickedoff:
i fuked up bio this year  ... i vow to get 50 in all my subjects next year (except for english lol)

gah, it said somatic cell? :[

Breast cancer is on the P53 gene though..?
So it is inherited?

Breast cancer is inherited anyway- we know this from real life...so surely its inherited

Cancer isn't quite that simple. There isn't a single mutation that can cause cancer. It requires around 3 to 4 'cancer genes' to be mutated before cancer actually begins. Most people who are said to have gotten their breast cancer genetically are only genetically pre-disposed to getting it, but there are environmental reasons too. The relatively well known BRCA 1 and 2 genes give around a 66% chance that the individual will get breast cancer, but it's not a certainty; that's why they aren't born with it. It requires these individuals to accumulate more mutations over the course of their life until they actually get cancer - it's just that they're already 1 strike down from a genetic perspective. The p53 gene that's being referred to here is even more complicated as it actually acts in a recessive manner, so in actual fact, it'd have little bearing on the mother's cancer status as she only has one copy.

[shea43]

I thought it wasnt too bad. Got it all done and I think only really made a few mistakes. Stupidly read the electrophoresis question wrong. Didnt realise that the band was above the well and so i wrote that the technician didnt use the restriction enzyme. But other than that I reckon that I got most questions alright without too many stupid mistakes

I also wrote that the technician forgot to use restriction enzymes.

For the qn where we had to draw a plasmid, I just drew a circle. Whats it really meant to look like?
And, for that cow qn, wheere we had to draw the band thing on the gel electrophoresis, where was it meant to go?

Yeah I just drew a circle and for the cow one I had one 105kb band and one 60kb band

[shinny]

Anyone care to give a rough outline of how this question went? I think people are confusing genetic pre-disposition to genetic causation.

it said that patient X suffers breats cancer, mutation on p53 allele, she has a single mutant allele and a sdingle normal allele.
asks if it would be expected that her daughter would present with a mutant allele of a normal allele.

logically, seemed like somatic mutation not germline so inferred duaghter would express normal allele onlyy?

I'm confused. Did she inherit this mutation on the p53 allele, or did it occur spontaneously? If she inherited it, there's a 50% chance her daughter will get it too. If she had it spontaneously, then it won't be passed on to her daughter.

haha dudee i was paraphrasing for ease of interpretation...asks essentially whether daughter would hav mutant allele or normal allele (determingin colour of dye schmuck)..
didnt mention whther muation was spontaneous, however strongly suggested that it was a subsitiution point mutation so i guess somaticc ?

If it says that there was a substitution in the mother, then I guess that's a somatic, hence it won't be passed on to the daughter. I guess you guys can work out what that means in terms of the dyes.

[cochra]

The breast cancer question didn't mention if the mutation was spontaneous or hereditary. However, since the micro-array only showed the red dye on one out of the four locations, i assumed that the mother had been homozygous for this mutation, indicating that it was probably a hereditary mutation.

[simpak]

It said that 60% of cancer cases involved people with this gene.
Which would, if I am not mistaken, infer genetic predisposition?
I don't remember reading that the mutation occured in a somatic cell anywhere in that text.
If they're going to assume everyone knew the mutation occured in the breast tissue in adulthood, then that's truly not very nice!

I said red or green, because the mother had both a mutant and a normal allele according to the results?  I was running out of time and relatively confused though.

[shinny]

The breast cancer question didn't mention if the mutation was spontaneous or hereditary.

Hmm that's strange. Could it have been inferred from anywhere? Would be useful if someone had the exam because whether it's spontaneous or hereditary pretty much solves the entire question =\

[10weid]

The breast cancer question didn't mention if the mutation was spontaneous or hereditary. However, since the micro-array only showed the red dye on one out of the four locations, i assumed that the mother had been homozygous for this mutation, indicating that it was probably a hereditary mutation.

hmmm except it showed that the mother hybridised to both green and red, meaning one copy of each allele hnce heterzyogous no?
and keep in mind that it asked wat kinda mutation it was, which was a point mutation.

[shea43]

I STUFFED THAT QUESTION UP -- THE DAUGHTER CANNOT GET IT CUZ THE MUTATION WAS IN A SOMATIC CELL   :tickedoff:
i fuked up bio this year  ... i vow to get 50 in all my subjects next year (except for english lol)

gah, it said somatic cell? :[

Breast cancer is on the P53 gene though..?
So it is inherited?

Breast cancer is inherited anyway- we know this from real life...so surely its inherited

Cancer isn't quite that simple. There isn't a single mutation that can cause cancer. It requires around 3 to 4 'cancer genes' to be mutated before cancer actually begins. Most people who are said to have gotten their breast cancer genetically are only genetically pre-disposed to getting it, but there are environmental reasons too. The relatively well known BRCA 1 and 2 genes give around a 66% chance that the individual will get breast cancer, but it's not a certainty; that's why they aren't born with it. It requires these individuals to accumulate more mutations over the course of their life until they actually get cancer - it's just that they're already 1 strike down from a genetic perspective. The p53 gene that's being referred to here is even more complicated as it actually acts in a recessive manner, so in actual fact, it'd have little bearing on the mother's cancer status as she only has one copy.

Ahk. In the question though it gave you a sequence of nucleotides and said that these were parts of alleles. Then it showed dyes if they had a correct sequence. There were 5 sequences that the mother had and one of them would show the green dye and one shows the red dye.

She had (like):
 GAACCTGA    GAACGTGA     GAACATGA     GAACTTGA

The first had the green and the second showed the red dye but these were all part of the same allele.
And then it said if the girl had like the first segment then what colour would the dye be

[physics]

I didn't finish i had 5 minutes to do question 6 and 7. cheer up people i didn't do muiltiple choice no time so i randomly circled.

[cochra]

The results didn't show that the mother had both a mutant and a normal allele. the green dye was from a normal example of that section of DNA. The red dye was her sample of that section. the fact that the green dye bound to the normal allele and the red one to the mutant allele probably meant that she had the same mutation in both copies of the gene. The green dye was just a sample of that gene, it had no connection to the mother.

[emkate]

it would be nice to actually read the question again..i wrote that it would have been green but  was running out of time so might have missed something. Does any one have a copy of the exam to post up?

[classy1112]

i have a copy of the exam