Biology: Genetics: Hardy-weinberg + restriction enzyme

• Biology
• foxyfresh
In summary, the conversation discusses various homework problems related to genetics, specifically the Hardy-Weinberg principle, genetic cloning, and restriction enzymes. The main confusion revolves around understanding the reasoning behind the book's answers. The summary provides brief explanations for each problem, including the relationship between genotype and allele frequencies, the use of probability in calculating DNA fragments, and the impact of somatic cell nuclear transfer on the physical characteristics of a cloned animal.
foxyfresh
Hi, everyone, I was hoping if you can clear up some confusion for me.
I have the questions and book answer to these homework problem. The hard part for me is understanding WHY these answer turn out to be the way it is.

1: Hardy-weinberg:

Homework Statement

14.4 Consider a population that, for unknown reasons, is not in Hardy-Weingberg equilibrium for some gene.
(a) can you calculate the genotype frequencies if you know the allele frequencies?
(b) can you calculate the allele frequencies if you know the genotype frequencies?
(A) No.
(B) Yes.

Homework Equations

So.. why is does it come out like this? Can you explain to me why these two answer are correct?

The Attempt at a Solution

Because, I thought if H-W doesn’t applied, you cannot calculate either of this answer..right?

------
Question 2:
1: Genetic Cloning/restriction enzyme

Homework Statement

10.13: A haploid genome size of about 100 Mb. If this genome is digested with NotI (an eight-baed cutter), approximately how many DNA fragments would be produced? Assume equal and random frequencies of the four nucleotides.

So, every 65,526 based, the enzyme makes a cut. Thus, 100,000,000 bp / 65,526 bp = 1527 fragments.

Homework Equations

so, why did you take the 4^8? how do you know to put "4" and put it to the 8th power? where is this formula even coming from?

The Attempt at a Solution

I, actually, have no idea..

Because, I thought if H-W doesn’t applied, you cannot calculate either of this answer..right?

--------
Question 3:

Homework Statement

10.6: You decide to clone your pet dog, which is brown with black spots. You take a few somatic cells from your dog and perform a somatic cell nuclear transfer procedure using an egg from a female dog that is black. In this procedure, the egg nucleus is removed and replaced with that from a somatic cell. What color fur will the puppy clone of your dog have?

Homework Equations

so, why does the book answer come out to be this way? Also, is the oocyte a fertilized or unfertilized egg, right? Since, this procedure could only work with an unfertilized egg?

The Attempt at a Solution

So.. my logic behind is this... So, is it b/c you have replaced the inner nucleus of the oocyte and replaced it with a somatic cell; thus, in turn, the oocyte will only expressed the somatic cell genotype ..which lead to the phenotype of brown with black spots. .. .
--------

foxyfresh said:
Hi, everyone, I was hoping if you can clear up some confusion for me.
I have the questions and book answer to these homework problem. The hard part for me is understanding WHY these answer turn out to be the way it is.

1: Hardy-weinberg:

Homework Statement

14.4 Consider a population that, for unknown reasons, is not in Hardy-Weingberg equilibrium for some gene.
(a) can you calculate the genotype frequencies if you know the allele frequencies?
(b) can you calculate the allele frequencies if you know the genotype frequencies?
(A) No.
(B) Yes.

Homework Equations

So.. why is does it come out like this? Can you explain to me why these two answer are correct?

The Attempt at a Solution

Because, I thought if H-W doesn’t applied, you cannot calculate either of this answer..right?

The genotype frequencies will always tell you the allele frequencies. For example, if you have 20 individuals who are AA, 10 individuals who are Aa, and 5 individuals who are aa, it's easy to count the number of A alleles (20*2 + 10) and the number of a alleles (10+ 5*2), and calculate the allele frequencies.

Question 2:
1: Genetic Cloning/restriction enzyme

Homework Statement

10.13: A haploid genome size of about 100 Mb. If this genome is digested with NotI (an eight-baed cutter), approximately how many DNA fragments would be produced? Assume equal and random frequencies of the four nucleotides.

So, every 65,526 based, the enzyme makes a cut. Thus, 100,000,000 bp / 65,526 bp = 1527 fragments.

Homework Equations

so, why did you take the 4^8? how do you know to put "4" and put it to the 8th power? where is this formula even coming from?

The Attempt at a Solution

I, actually, have no idea..

Here's a related problem that might get you thinking in the correct direction: If you throw a six-sided dice four times in a row, what is the probability of rolling a 1, then a 2, then a 3 then a 4?

Question 3:

Homework Statement

10.6: You decide to clone your pet dog, which is brown with black spots. You take a few somatic cells from your dog and perform a somatic cell nuclear transfer procedure using an egg from a female dog that is black. In this procedure, the egg nucleus is removed and replaced with that from a somatic cell. What color fur will the puppy clone of your dog have?

Homework Equations

so, why does the book answer come out to be this way? Also, is the oocyte a fertilized or unfertilized egg, right? Since, this procedure could only work with an unfertilized egg?

The Attempt at a Solution

So.. my logic behind is this... So, is it b/c you have replaced the inner nucleus of the oocyte and replaced it with a somatic cell; thus, in turn, the oocyte will only expressed the somatic cell genotype ..which lead to the phenotype of brown with black spots. .. .

You basically have the correct answer. The dog's traits are encoded in its DNA. Removing the nucleus from the oocyte remove's the oocyte's original DNA, including any DNA that would cause the dog to have black hair. Therefore, because the clone contains only DNA from your pet dog, its physical characteristics (at least those dependent on genes) will come from only your pet dog and not from the egg donor dog.

An oocyte is an unfertilized egg. I think somatic cell nuclear transfer only works with unfertilized eggs although I am not 100% sure that this is true.

Ygggdrasil said:
The genotype frequencies will always tell you the allele frequencies. For example, if you have 20 individuals who are AA, 10 individuals who are Aa, and 5 individuals who are aa, it's easy to count the number of A alleles (20*2 + 10) and the number of a alleles (10+ 5*2), and calculate the allele frequencies.

Here's a related problem that might get you thinking in the correct direction: If you throw a six-sided dice four times in a row, what is the probability of rolling a 1, then a 2, then a 3 then a 4?

You basically have the correct answer. The dog's traits are encoded in its DNA. Removing the nucleus from the oocyte remove's the oocyte's original DNA, including any DNA that would cause the dog to have black hair. Therefore, because the clone contains only DNA from your pet dog, its physical characteristics (at least those dependent on genes) will come from only your pet dog and not from the egg donor dog.

An oocyte is an unfertilized egg. I think somatic cell nuclear transfer only works with unfertilized eggs although I am not 100% sure that this is true.

Can you explain further why can't you do the opposite by "calculate the genotype frequencies if you know the allele frequencies"?

Well, let's say you have 10 A alleles and 10 a alleles. You can put these alleles together in many different ways to get different combinations of genotypes. For example, you could put them together as 5 AA individuals and 5 aa individuals. Or you could put them together as 5 Aa individuals. Or you could have 1 AA individual, 3 Aa individuals, and 1 aa individual. etc.

Because there are many different ways of combining the alleles to get different genotypes, you cannot determine genotype frequencies from allele frequencies.

Ygggdrasil said:
Well, let's say you have 10 A alleles and 10 a alleles. You can put these alleles together in many different ways to get different combinations of genotypes. For example, you could put them together as 5 AA individuals and 5 aa individuals. Or you could put them together as 5 Aa individuals. Or you could have 1 AA individual, 3 Aa individuals, and 1 aa individual. etc.

Because there are many different ways of combining the alleles to get different genotypes, you cannot determine genotype frequencies from allele frequencies.

Thank you SO MUCH! I LOVE YOU! :D

1. What is the Hardy-Weinberg principle in genetics?

The Hardy-Weinberg principle is a mathematical equation that explains the relationship between allele and genotype frequencies in a population. It states that in a large, randomly mating population without outside forces (such as natural selection or genetic drift), allele and genotype frequencies will remain constant from generation to generation.

2. How is the Hardy-Weinberg principle used in genetics research?

The Hardy-Weinberg principle is used as a null hypothesis to determine if a population is evolving. By comparing the observed allele and genotype frequencies to the expected frequencies calculated using the Hardy-Weinberg equation, researchers can determine if there are any evolutionary forces at work in a population.

3. What is the role of restriction enzymes in genetics?

Restriction enzymes are enzymes that cut DNA at specific recognition sites. They are commonly used in genetics research to cut DNA into smaller fragments, which can then be analyzed and manipulated for various purposes, such as gene cloning or DNA sequencing.

4. How are restriction enzymes named?

Restriction enzymes are named after the bacteria from which they were originally isolated. The first letter of the name represents the genus of the bacteria, while the second and third letters represent the species. For example, the restriction enzyme EcoRI was isolated from the bacteria Escherichia coli RY13.

5. Can the Hardy-Weinberg principle be applied to all populations?

No, the Hardy-Weinberg principle is based on several assumptions, including random mating, no outside evolutionary forces, and a large population size. In reality, these conditions are rarely met in natural populations, so the Hardy-Weinberg principle is mainly used as a theoretical model and may not accurately represent all populations.

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