The answer should be altitude
Answer:
Channel proteins and Carrier proteins
Explanation:
These are type of membrane proteins that transcend the entire length of phosphoslipid bi- layer in the plasma membrane.They facilitate the movement of ions and molecules across the walls of the plasma membranes.
Generally, substances like glucose, amino acids, are too large to pass through the phopholipid bilayers. Likewise ions of potassium, sodium calcium, because of their polarities can not pass through either. They are ferried across the phospholipid by group of protein structures called channel proteins. Some are also transported across by carrier proteins. The process by which these protein structures aided the diffusion of substances across the phospholipid bilayer is called Facilitated diffusion.
Channel proteins are pores, that are filled with water molecules with the entrance well gated. That is the entrance is controlled by part in the inner structure of the protein which can open or close the pores like a gate to control the movement of ions across it. e.g Sodium channels are gated for movement of sodium ions by voltage or ligands(chemicals) during nervous transmission to elicits action potential. Like wise Potassium channels allow diffusion of potassium ions across the phospholipid bilayers. it gates are shut when sodium channels are open; this regulate ion exchange.
Their structures are well fixed in shape , specific to the substance or ions being transported;and the rate of diffusion depends on the like hood of opening of the gate or closure.
Carrier molecules also in the membranes do not have a fixed shape, and their transport direction is determined by the direction of concentration gradients. Thus they can flip on either sides of the membranes to aid diffusion across. Their movement can be both passive and active, and the rates of diffusion depends on the number of available carrier proteins in the membrane. They are also specific to the ions they transport.And are not gated,
Therefore these two membrane integral proteins facilitate movements of substances across the phospholipild bilayers
To choose the strand the promoter acts to aim the RNA polymerase.
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What does RNA polymerase do?</h3>
RNA polymerase synthesizes RNA by following a strand of DNA. The primary transcription enzyme is RNA polymerase. When RNA polymerase connects to a promoter sequence near the start of a gene, transcription starts (directly or through helper proteins). To create a fresh, complementary RNA molecule, RNA polymerase employs one of the DNA strands (the template strand) as a template.
Three distinct RNA polymerases (RNAPs), which transcribe various kinds of genes, are present in all eukaryotes. RNA polymerase I transcribe rRNA genes, RNA polymerase II transcribes mRNA, miRNA, snRNA, and snoRNA genes, and RNA polymerase III transcribes tRNA and 5S rRNA genes.
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