<h2>Lac operon </h2>
Explanation:
Lac operon present in prokaryotic chromosomes whose product involves in transportation and catabolism of lactose
- Lac operon consists of three structural genes called Lac Z,Lac Y and Lac A and a regulatory element(promoter and operator)
- Lac I gene is present outside the Lac operon,act as regulatory gene and control the expression of Lac operon genes
- Lac Z codes for β galactosidase which converts lactose into allolactose
- Lac Y codes for Lac permease which act as a membrane transporter and transport lactose into the cells
- Lac A codes for transacetylase which neutralize the toxic effects of lactose
Lac operon in absence of lactose
- In absence of lactose Lac operon exists in switch off state
- Lac I gene produces Lac repressor which binds to operator region and prevent binding of RNA Polymerase thus blocks transcription
Lac operon in presence of lactose
- In presence of lactose Lac operon exists in switch on state
- In presence of lactose few molecules of Lac operon enzyme catalyse conversion of lactose to allolactose
- Allolactose act as an inducer,binds to the Lac repressor and induce conformational changes causing dissociation of Lac repressor from operator
- In absence of Lac repressor RNA Polymerase binds to the promoter and starts transcription of genes which catabolize lactose
Lac promoter is a weak promoter and direct transcription of Lac operon genes in very low level in presence of lactose
- For higher level expression of Lac operon genes,operon system require conversion of weak promoter to strong promoter which is always mediated by catabolite protein-cAMP complex(CAP-cAMP complex)
- CAP cAMP complex binds to the upstream of promoter called CAP binding site and stimulate expression of Lac operon genes by facilitating binding of RNA Polymerase
- Catabolite activator protein(CAP) or cAMP receptor protein(CRP) activate when cAMP binds
- cAMP is a secondary messenger synthesized from ATP and act as co-activator of CRP
- With respect to CAP cAMP complex Lac operon system is positively controlled
- In prokaryotic cell cAMP is very low when glucose concentration is relatively high and vice versa
- At high concentration of glucose the growth rate is maximum and lactose catabolism is repressed called catabolite repression
Answer:
Explanation:
Paleontologists are scientists that study the history/existence of past lives by collecting and examining fossils. They use these fossils to determine the history and age an organism has existed. Fossils are remains of dead organisms (plants and animals) which serve as evidence of past lives that have existed on earth in the past. They could include bone remains or footprint of this animals.
Fossils (from bones) are however mostly incomplete because they decompose before they are "stored naturally" by sediments which covers them. When scientists discover this incomplete fossils, they are compared (if there has been similar fossils discovered before then) and are stored and transferred to the lab for examination. This examination includes anatomical comparison (to determine relatedness with other fossils/organisms), carbon dating (to determine age) and data comparison (which includes location and type of soil and habitat).
I think the proper wording would be veef.... get it... cause their vegan.... I'm gonna go now
Answer:
The correct answer are option A. "A microbiologist with the U.S. Geological Survey grew crescent-shaped fungal spores in a lab on refrigerated plates" and option C. "A specialist with the New York State Health Department detected crescent-shaped fungal spores when examining a sample swabbed directly from a living bat with a white nose".
Explanation:
Doctor Blehert and Doctor Behr are two scientists that are studying the relationship between fungal disease and the development of the bat white nose syndrome. In order to prove that bat white nose syndrome is caused by a fungal disease Blehert and Behr first took samples in the field and later analyzed the samples in the laboratory. First, a specialist with the New York State Health Department detected crescent-shaped fungal spores when examining a sample swabbed directly from a living bat with a white nose. Later, the samples taken from the shaped fungal spores were grew in the laboratory on refrigerated plates by a microbiologist with the U.S. Geological Survey. After analyzing the samples, the scientists conclude that the bat white nose syndrome is caused by a fungal disease.
The time when you can't see any of the moon at all is called "New Moon".
14.77 days later, the phase is "Full Moon".
