Answer:
<u>d. Transport proteins within the membrane serve as a tunnel for molecules to enter the cell.
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Explanation:
Solutes are typically moved across the cell through either passive or active transport. The cells, surrounded by a bilipid layer or plasma membrane is amphiphlic- its polar, hydrophilic lipid heads face outwards, while their non-polar hydrophobic lipid tails face inwards towards each other.
While lipid-soluble molecules move across the layer easily, it is also difficult for charged and also large molecules to move across its surface, into the cell. Transmembrane channels, <u>embedded within the membrane</u>, help to maintain selective permeability as transport proteins, pores and gated channels. Simple diffusion happens as a method of passive transport in cells through plasma membranes.
The solutes travel through the plasma membrane in the process of diffusion from regions of high concentration to regions of low concentration; this occurs without the use of energy. <u>Molecules moving against their concentration require active transport mechanism to cross the membrane</u>.
Abiotic: which are the non-living factors and chemicals in environments which can affect the ecosystem.
Answer:
The correct option is d. it causes exchange diffusion
Explanation:
Amphetamines are synthetic substances with a stimulating effect. Their action lies mainly in increasing synaptic levels of monoamines by various mechanisms, including diffusion exchange through membrane transporters. Amphetamine increases extracellular concentrations of serotonin by displacing the neurotransmitter from its specific presynaptic transporter. When amphetamine binds to serotonin transporters, on the one hand it prevents it from entering the terminal and on the other it reverses the recapture mechanism so that serotonin leaves the synaptic space.
Answer:
A. The tails do not interact with the DNA
Explanation:
The acetylation refers to the transfer of the acetyl group from Acetyl-CoA to the N-terminal of the histone protein.
Lysine residues (positively charged amino acid) are present at the end of the N-terminal of the histone protein which is neutralized by the acetyl group.
This loses the compaction between the positively charged histone and the negatively charged DNA and the DNA becomes more relaxed. This relaxed state allows the transcription factors to easily bind the DNA and therefore the DNA becomes transcriptionally active.
Thus, Option-A is correct
Answer:
The correct answer is ''Translocation.''
Explanation:
Translocation is a chromosomal abnormality that is due to a change in position of a chromosomal segment to another non-homologous chromosome of the same nucleus or to another part of it. It is produced by the exchange of segments between two chromosomes without loss of genetic material is called reciprocal or balanced translocation, when it gives rise to monocentric chromosomes.Translocations can be detected cytologically because the structural heterozygote forms a quadrivalent (4-chromosome association) in meiotic prophase. Sometimes they can also be detected by changes in the size of the chromosomes if the exchanged segments are of different lengths.
