<span>A. chromosomes
Chromosomes is where the DNA is structurally formed and determined.
Almost all organisms have a chromosome which is a significant unit in a cell of every living thing. In most prokaryotic organisms these chromosomes are just plastered in its cytoplasm without a fully developed nucleus contrary to the eukaryotes.</span>
<h2>b) option is correct </h2>
Explanation:
- Some bacterial toxins cause disease by altering the activity of G protein, cholera toxin is one of them
- Cholera toxin catalyse ADP ribosylation of Gs and blocks GTPase activity thus Gs GTP become permanently active
- Constitutive activation of Gs protein continuously induce adenylyl cyclase, cytosolic cAMP level rises that leads to activation of protein kinase A (pKA)
- Activated pKA catalyse phosphorylation of two transmembrane proteins of intestinal epithelial cells:
- CFTR cause excessive outflow of Cl- ion and Na+ H+ exchange cause efflux of Na+ ion, both enters in gut and form Na+ Cl-
- Na+Cl- leads to outflow of water from the gut, resulting in diarrhea and dehydration and this condition may cause death of organisms due to loss of water and ions
Asymmetry is the lack of symmetry.
Answer:
The colonies are carrying the resistance genes from plasmids
Explanation:
Bacteria can acquire beneficial characteristics that they didn’t have. One way for these is through plasmids, which ones are little fragments of DNA that usually contains resistance genes (for antibiotics, disinfectants, heavy metals, etc.) or other capacities, like the ability to use some substances (for example sugars).
In this specific situation, we already know that the plasmid carrying genes for tetracycline resistance and the <em>lacZ</em> gene.
A little explanation:
Tetracycline is an antibiotic that inhibits bacterial growth and kills the bacteria. The bacteria can “fight” to this antibiotic if it has a resistant gene, the result is that the antibiotic can’t affect the bacteria and survive. An analogy is like a Police Officer (bacteria) that have a bulletproof vest (tetracycline-resistant gene) so the bullets (tetracycline) didn’t affect the police.
In the case of X-gal, is a compound consisting primarily in one sugar called galactose. Not all bacteria can eat galactose, they need an enzyme called β- galactosidase (comes from <em>lacZ</em> gene) that helps the bacteria “eat” the sugar (cuts the sugar in little pieces so the bacteria can eat).
Then, as the bacterial colonies can grow in the medium with tetracycline and X-gal, we know that those bacteria are carrying the resistance genes for tetracycline (does not affect the bacteria) and the <em>lacZ</em> gene (bacteria produce β- galactosidase that cuts galactose). These genes are coming from the plasmids because we already know that the plasmid carries these genes and not from the exogenous DNA.
Answer:
The correct option is the number 2. Cystic fibrosis
Explanation:
Cystic fibrosis is a hereditary disease that affects the glands that produce mucus, sweat and digestive juices, this genetic disorder makes the secretions more sticky and thick, they accumulate and produces blockage in the tubes, ducts and passages, in particular in the lungs and pancreas.
The mucus block the ducts that carry digestive enzymes from the pancreas to the small intestine. Without these digestive enzymes, the intestines are not able to completely absorb nutrients in the food. The result is often, little increase in weight and growth, intestinal obstruction, particularly in newborns (ìleo meconium), among others.
Cystic fibrosis also affects the epithelial cells of the sweat glands, children suffering from this disorder may have a kind of salt layer on the skin. They can also lose abnormally high amounts of salt when they sweat on hot days.
