<span>There are three basic chemical components of DNA - 1. Four "Nucleic acids", 2. Deoxyribose sugar, and 3. Phosphate backbone. The overall shape of the molecule is a double-stranded, double helix. It looks a bit like a spiral staircase wrapped around a spiral staircase. Phosphate groups outside, nucleic acids inside the helix,</span>
To only allow through certain items, and block the rest.
Testosterone helps RNA polymerase transcribe certain genes. It is a steroid hormone.
<h3>Testosterone and gene expression</h3>
Testosterone is a steroid hormone produced in the gonads and secreted by the Leydig cells.
During gene expression, testosterone helps to RNA polymerase, which is a key enzyme that acts during transcription.
During transcription, RNA polymerase sequentially adds nucleotides in order to form a single strand RNA.
Learn more about transcription here:
brainly.com/question/1048150
Answer:
D. Mass extinction events separate the three eras from each other
Explanation:
The Phanerozoic is an eon, thus it is representative of the largest unit of geological time. It is further divided into three eras. The three eras of the Phanerozoic are the Paleozoic, Mesozoic, and Cenozoic. These three eras have been divided on the basis of mass extinction events. The Paleozoic ends with the mass extinction at the end of the Permian period, which is also the largest mass extinction ever, and it also marks the beginning of the Mesozoic. The Mesozoic ends with the mass extinction at the end of the Cretaceous period, occurring because of a large meteorite or comet impact, marking the beginning of the Cenozoic era. The Cenozoic era is still going, and even though there have been extinction throughout it, none of them has been of a scale big enough to be considered as a mass extinction, so until something like that happens, this era will continue to exist.
Answer:
The cell membrane controls what goes in and out by having protein channels that act like funnels in some cases and pumps in other cases. Passive transport does not require energy molecules and happens when a funnel opens in the membrane, letting molecules flow through.
