The treatment for a nephrolith lodged in the ureter is called

Conventional wisdom holds that the development of separate species happens quickly, most often when populations become separated

Genrish500 [490]

Answer: D. allopatric; breakdown

Explanation:

Allopatric speciation is a type of speciation whereby individuals of the same biological population becomes separated up to the extent that there will no longer be gene flow between them.

3 0

3 years ago

A scientist has a very small sample of DNA. To analyze the DNA, which would be the MOST USEFUL first step for the scientist to f

UNO [17]

Pretty sure C
A. Doesn’t make sense bc restriction enzymes cleave dna into fragments
B. PCR is used to identify organisms that are difficult to culture
D. Once again restriction enzymes just cut the dna up

6 0

3 years ago

In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The al

Lerok [7]

Answer:

The parent's genotypes are:

Ddpp - tall, white parent

ddPp - dwarf, purple parent.

Explanation:

This question involves two different genes coding for height and flower color in pea plants. The alleles for tallness (D) and purple color (P) are dominant over the alleles for dwarfness (d) and white color (p) respectively.

According to this question, a tall plant with white flowers is crossed with a dwarf plant with purple flowers to produce the following proportion of offsprings: 1/4 tall purple, 1/4 tall white, 1/4 dwarf purple, and 1/4 dwarf white.

Since some of the offsprings contain recessive alleles for both or either genes, the dominant traits of the parent is controlled by an heterozygous genotype. This means that the tall plant with white flowers has a genotype: Ddpp while the dwarf plant with purple flowers has the genotype: ddPp. In a cross between Ddpp × ddPp, 1/4 of each combination of alleles is produced in the offsprings (see punnet square in the attachment).

3 0

3 years ago

The global human population was growing exponentially up until second and a half of the 20th century according to the ideas of T

Harrizon [31]

Answer: C

No, because the human population depends on limited resources, and may suffer from war, disease, and famine l.

4 0

4 years ago

A gene is involved in promoting limb development in humans. The gene is initially weakly activated during the limb induction pha

Anna [14]

Answer:

1. If the gene is weakly activated, it likely lacks repressive histone modifications, but may also lack the presence of histone marks associated with strong transcriptional activation such as acetylation.

When the gene is strongly activated, it likely lacks repressive marks (such as H3K9me2/3 and H3K27me3 - both examples of repressive histone methylation) and might possess some activating histone acetylation marks, such as H3K4ac, and active histone methylation such as H3K4me3

<em>An aside: The pattern and presence of different histone modifications would depend on the gene, but based on the fact that it is a developmental gene, I would assume that H3K27me3 and H3K4me3 are at play (these are part of the Polycomb/Trithorax system)</em>

<em />

After limb growth is complete, the gene is turned off. Repressive histone methylation marks would be associated with this state, such as the aforementioned H3K9me2/3 or H3K27me3.

2. Histone modifications are tightly linked to genome organisation. Histone methylation marks associated with repression such as H3K27me3 and H3K9me3 are associated with compact chromatin structures, which restrict the access of transcriptional machinery and other positive regulators. Conversely, histone marks associated with gene activation are associated with a more permissive chromatin environment that facilitates the binding of factors associated with gene expression. In the case of histone acetylation, the acetyl mark directly removes the positive charge of chromatin, relaxing its interaction with negatively charged DNA.

3. If the inappropriate activation of this gene caused a cancerous tumor, this gene would be referred to as an oncogene (or a proto-oncogene for the term before it is inappropriately activated).

Typically, there are two classes of genes that lead to cancer: tumor-suppressor genes and oncogenes. Tumor suppressor genes lead to cancer when their protective activity is reduced or demolished, leading to the production of cancer cells. Oncogenes lead to cancer when they become over active. Oncogenes are often genes associated positively with growth and proliferation, consistent with the gene in this example.

8 0

3 years ago