Need help with homework

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Need help with homework

Post by sillygrandma » Sat Nov 11, 2006 9:13 pm

Help! I signed up for a 4-wk. intensive in Genetics to fullfill my science requirement in order to graduate with my Bachelor's in May. I'm an A student who normally can read through something twice and get the gist of what I'm reading.

We have no text. My professor gives us his lecture notes from week to week and, so far, they are least to me. My husband, who loves science, hasn't been that much help as I'm not sure he understands either.

Would somebody out there who understands genetics please help me with my homework for the next 3 weeks? I got the 1st week done by myself.

Here's a couple of the questions:

1. The lack of pigmentation called albinism is the result of a recessive allele and normal pigmentation is the result of its dominant allele (A). Two normal parents have an albino child. Determine the probability that the next child is albino. Please show how you got this answer.

2. The gene for albinism is recessive to the gene for pigmented skin. An albino man married a normally pigmented woman who had an albino mother. Show the types of children this couple may expect and the proportion of each. Show how you got the answer.

I would not ask for help with my homework if I were not desperate; I normally try to do my own homework for myself, but I am lost. I have 2 regular homework essays to write this week, plus a chapter on my thesis, plus the readings for the week, plus the homework for this class. If someone will help me on these 2 questions, I'll post some more. I will be everlastingly grateful. I'm almost 60 years old and I want to be the first in my family to graduate college.

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Post by druid » Sat Nov 11, 2006 9:53 pm


Because Father and Mother are both normally pigmented and have a albino child they're both heterozygous:
A/a X A/a => 1/4 A/A + 1/2 A/a + 1/4 a/a
Thus, the next child will ba albino with probability of 25%.


Normally pigmented woman can be either homozygote A/A or heterozygote A/a. Because she has albino mother ( which must be a/a ), she carries a allele, she's heterozygous A/a.

a/a X A/a => 1/2 A/a + 1/2 a/a

By the way, about what science is your bachelore?

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Post by sillygrandma » Sun Nov 12, 2006 12:40 am

By the way, about what science is your bachelore?[/quote]

My bachelor's degree will be in Family Life Education-Psychology, but this was the only science that was available online from the college I attend. I'm in Texas and they are on the west coast. I'm extremely rural, so I needed an online college to attend. Had I known that this was going to be this hard, I would have tried to CLEP out on, say, Biology or something a bit easier to understand. It's too late now, though, so I've got to make the best of a bad situation.

My husband tried to help but gave up, so I am slogging through this alone for the next 3 weeks. I've spent the last 6 hours trying to get my homework done and am not much further along than when I started. This part is the lab. For the regular homework, he gave us links that don't work to find information and I'm using Wikipedia instead. I just want to sit down and cry, but I don't have time.

Thanks for the help. Here's some more questions:

1. The ability to taste a bitter chemical, phenylcarbamide (PTC) is due to a dominant gene. A man who is a taster marries a woman who is a nontaster, and they have a child who is a nontaster. What would you know about the father's genotype. Explain your answer using a Punnett square.

2. Suppose you are a marriage counselor and a young woman comes to you for advice. She tells you that her brother has hemophilia, but both her parents are normal. She wishes to marry a man who had an uncle with hemophilia and wants to know the probability of children she may have of acquiring the disease. What would you tell her, and how would you explain your conclusions? (The gene for hemophilia is a sex-linked gene (X linked) and it is recessive to the gene for normal blood.)

3. Draw 2 sets of pictures that illustrate how trisomy-21 occurs. One set of pictures should illustrate how it occurs from non-disjunction during anaphase I and the 2nd set of drawings should illustrate how it arises during anaphase II. You will need to unite the abnormal gamete with a normal gamete in order to produce a zygote with trisomy-21.

4. Draw 2 sets of pictures that illustrate how a Turner Syndrome child is produced.

Any help you can give would be so appreciated. I have a 3.86 grade point and am afraid it is going to plummet because of this class. I am so close to the end and had so much hope to graduate with honors. I've worked so hard for it to be taken away now.

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Post by LilKim » Sun Nov 12, 2006 5:24 pm

hey there!

I don't want to give you the answers cuz that won't help you to understand what you're doing... and that's not beneficial to either you or me.... because you'll never be able to complete your assignments independantly.

I STRONGLY suggest that you try... and even if you're COMPLETELY wrong... we'll be able to see where you're going wrong and help you to figure-out correct answers.

Additionally, If you have access to a scanner... try to figure out your answers on paper and then upload them on here or send me a PM and i'll give you my e-mail address... and i'll go over your work with you via e-mail or .. whatever.

But to be honest with you Genetics can be quite tricky.. and it only gets worse... so you need to try to understand the basics that you can understand the more complicated stuff (it doesn't get any easier!!).

If you are serious... i will help you (and 99.99999% of the people on this site will help you) earn an "A" .. that's not a problem.

buena suerte!

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