38 through 40 need help

Biology

1 answer:

harkovskaia [24]4 years ago

4 0

38. There are three main steps to DNA replication: initiation, elongation, and termination. In order to fit within a cell's nucleus, DNA is packed into tightly coiled structures called chromatin, which loosens prior to replication, allowing the cell replication machinery to access the DNA strands.

39. Cancer is primarily a disease of ageing epithelia, and of ageing individuals. We now possess detailed insights into the changes in cell regulatory genes and DNA repair systems which accumulate with time and which manifest in malignancy.

40. Proto-oncogene: A normal gene which, when altered by mutation, becomes an oncogene that can contribute to cancer. Proto-oncogenes may have many different functions in the cell. Some proto-oncogenes provide signals that lead to cell division. Other proto-oncogenes regulate programmed cell death (apoptosis). Proto-oncogenes (unmutated oncogenes) stimulate cell division in a regulated manner. Proto-oncogenes include growth factors, growth factor receptors, and cyclins. Oncogenes are mutated forms of these genes that result in unregulated stimulation of cell division. Tumor suppressor genes prevent cell division.

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14). During the early 1700’s, a small group of pacifist Protestants fled Germany to avoid religious persecution. This group, the

abruzzese [7]

A) In the Dunker population, the frequency of IB allele is 0.3 and the frequency of i allele is 0.4. In the general population, the frequency of IB allele is 0.1 and the frequency of i allele is 0.5.

If:
$I^{A}$ - the frequency of IA allele
 $I^{B}$ - the frequency of IB allele
 $i$ - the frequency of i allele

Then:
 $I^{A} I^{A}$ + $I^{A} i$ - the frequency of individuals with A blood type
 $I^{B} I^{B}$ + $I^{B} i$ - the frequency of individuals with B blood type
 $ii$ - the frequency of individuals with O blood type

Let's first take a look on the Dunker population:
$I^{A} = 0.3$
$ii=0.16
$

Since there is only one possible genotype for O individuals - ii - the frequency of the allele i is square root of the frequency of O individuals:
 $i= \sqrt{ii}$
⇒ $i = \sqrt{0.16}$
⇒ $i=0.4$

Now, we have the frequencies of two alleles ( $I^{A}$ and $i$ ). To calculate the frequency of $I^{B}$ allele, we will use the formula:
 $I^{A} + I^{B} + i = 1$
⇒ $I^{B} = 1- I^{A} - i$
⇒ $I^{B} = 1-0.3-0.4$
⇒ $I^{B} = 0.3$

Now, in the general population:
$I^{A} = 0.4$
$ii=0.25$

Similarly to the work for the Dunker population:
 $i= \sqrt{ii}$
⇒ $i = \sqrt{0.25}$
⇒ $i=0.5$

$I^{A} + I^{B} + i = 1$
⇒ $I^{B} = 1- I^{A} - i$
⇒ $I^{B} = 1-0.4-0.5$
⇒ $I^{B} = 0.1$


b) A founder effect is a result of geographical separation of a few individuals from the original population. Those founding individuals will form a new population. The Dunker population was not only geographically separated, but also genetically. The group interbreeding was present resulting in increasing those allele frequencies that were the most common in the founding population. In this case, the most individuals from the founding population had B blood type.

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