The electron transport chain (ETC) is the final step of cellular respiration and takes place in the mitochondrion.
- The final step in cellular respiration is the electron transport chain. This is sometimes abbreviated as ETC. ETC needs oxygen, which means aerobic process. It occurs at the edges of the inner lining of mitochondria. These handles are called cristae.
<span>They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins.</span>
Answer:
According to the diagram, cell growth and preparation occur in steps 2 and 4, corresponding to phases G₁ and G₂ of cell cycle.
Explanation:
G₁ phase consists of the beginning of the cell cycle, following the process of previous division, and occurs in a cell that prepares for a next division. In this phase growth depends on the proliferation of mRNA to increase protein synthesis.
G₂ phase —third phase of the cycle— is the continuation of the process of cell growth induced by protein synthesis. Changes occur at the level of cellular components, as preparation of the cell prior to division.
Complete question:
In a separate study, 68 rock pocket mice were collected from four different, widely separated areas of dark lava rock. One collecting site was in Sonora, Mexico. The other three were in Chihuahua, Mexico. Dr. Nachman and colleagues observed no significant differences in the color of the rocks in the four locations sampled. However, the dark-colored mice from the three Chihuahua locations were slightly darker than the dark-colored mice from the Sonora population. The entire Mc1r gene was sequenced in all 68 of the mice collected. The mutations responsible for the dark fur color in the Sonora mice were absent from the three different populations of Chihuahua mice. No Mc1r mutations were associated with dark fur color in the Chihuahua populations. These findings suggest that adaptive dark coloration has occurred at least twice in the rock pocket mouse and that these similar phenotypic changes have different genetic bases.
How does this study support the concept that natural selection is not random?
Answer:
The study supports the concept that natural selection is not random because in different areas with the same or very similar environmental characteristics, the same phenotype was produced by different types of mutations.
Explanation:
All of the sampled animals are inhabiting dark substrate. Probably animals needed to camouflage to survive. Natural selection must have driven them to produce dark color, similar to the substrate color. So animals from the different regions suffered different mutations that drove them to have almost the same dark fur color. The environmental condition is favoring the same phenotype.
