This is known as active transport. This is usually used for cells to gain something that they already have a lot of, like glucose.
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Are a special type of interaction between species
Answer
3,1,2,4
Explanation:
Through the mechanism of RNA interference (RNAi), short RNAs can inhibit gene expression. RNAi can function at transcriptional level, translational level, and mRNA stability.
RNAi mechanism has numerous biological functions; it can affect development, for instance in the worm C. elegans, or it can be utilized by plants to evade viral infection.
These short RNAs (abt 23 bp long) also known as siRNAs (short interfering RNAs) are products of long dsRNAs which are cleaved by nuclease Dicer. The siRNAs regulate a nuclease complex called RISC (RN-induced silencing complex) leading to repression of gene expression via three distinct ways;
a) Destroy mRNAs that have complementary sequence with the siRNA
.
b) Inhibit translation of mRNAs that have complementary sequence with the siRNA.
c) Induce chromatin modification within the promoter of these homologous (complementary) genes, thus silencing them.
Answer:
- Cortisol passes through the plasma membrane into the cytoplasm.
- Cortisol- receptor complex forms in the cytoplasm.
- Cortisol- receptor complex enters the nucleus where it binds to genes.
- Cortisol- receptor complex acts as a transcription factor.
- The transcripted mRNA is translated into a specific protein.
Explanation:
<em>Cortisol is a small, hydrophobic steroid hormone that can pass through the plasma membrane cells. In target cells, cortisol binds to the intracelullar receptor protein in the cytoplasm, forming a hormone- receptor complex. The hormone- receptor complex then moves into the nucleus and acts as a transcription factor, binding to specific genes and activating their transcription into mRNA.</em>
<em>The mRNA that is produced is eventually translated into specific proteins.</em>
<em>Proteins are produced in response to the cortisol signal function in the stress response. For example, some of these proteins aid in elevating glucose levels in the blood, helping an animal to meet the demands of starvation or intense physical activity.</em>