Answer:
4.5 billion years ago
Earth hasn't always been a blue and green oasis of life in an otherwise inhospitable solar system. During our planet's first 50 million years, around 4.5 billion years ago, its surface was a hellscape of magma oceans, bubbling and belching with heat from Earth's interior.
Explanation:
Hey there,
Homozygous- <span>When an individual has two of the same allele, whether dominant or recessive, they are </span>homozygous<span>.
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Answer:
(b) Voltage gated
Explanation:
The cell membrane acts as a barrier that separates two aqueous media of different composition, the extracellular and the intracellular, regulating its composition. Most of the liposoluble drugs and solutes, when not ionized, directly cross the cell membrane through a passive diffusion process, which facilitates the passage of the medium where it is more concentrated to the one that is more diluted. The difference in concentration between the two media is called the concentration gradient, and diffusion will continue until this gradient is eliminated. According to Fick's law, the speed of this process will be much faster the higher the concentration gradient and the liposolubility of the molecule and the smaller its size.
More hydrophilic molecules, such as ions, are immiscible in membrane lipids and pass through specific specific transport mechanisms. In some cases, ions pass through hydrophilic pores called ion channels, and in others a favor of their concentration gradient is transported by binding to the transporter or transporter proteins. Both transport systems are passive and therefore do not consume energy. The great advantage is that the ion channels allow the flow of ions through a much higher speed than that of any other biological system. The flow of ions through each channel can be measured as an electric current, which is capable of producing rapid changes in membrane potential.
Answer:
It decreases the levels of cAMP in the cell, repressing transcription from the lac operon.
Explanation:
When glucose is absent, cAMP serves as coactivator binds to CRP, the catabolite gene activator protein. The CRP-cAMP complex binds to the site near the lac promoter and stimulates the expression of the operon by RNA polymerase many folds.
Catabolite repression refers to inhibition of the synthesis of enzymes of lactose catabolism when glucose is present as an energy source. In the presence of glucose, synthesis of cAMP is inhibited resulting in its lower cellular concentration. The lower cAMP levels do not allow the binding of cAMP and CRP. The result is reduced expressed of lac operon.
Answer:
The strands of mRNA move through the ribosome from A site to the P site and exist at E site. The molecules of tRNA bind to the molecules of mRNA at the A site before moving P site where amino acids are attached to the end of the growing peptide chain.
Explanation:
