Changes in the dna are called mutations. They can occur spontaneously. Mutations can only be passed down in gametes--sperm and egg cells. with Darwins theory at mind a mutation needs to pass the test of natural selection to remain in the gene pool. So purposly making mutation or altercations may end in diseases/illnesses or in some cases death because they body can not take it.....hope this helps if it doesnt im sorry!
Answer:
There are many points at which eukaryotic gene expression can be controlled, through pretranscriptional control, transcriptional control, and posttranscriptional control
Explanation:
The pretranscriptional control determines the accessibility of chromatin to the transcription machinery. It is affected by supercoiling and methylation. It is also known as epigenetic regulation, and it does not depend on the sequence but on the conformation of the DNA.
While transcriptional control determines the frequency and / or speed of transcription initiation through the accessibility of the start sites, the availability of transcription factors and the effectiveness of promoters.
The post-transcriptional control is the one that is exercised once the transcript has finished synthesizing. It can be of several types:
• Maturation control: As the RNA adjustment can be made.
• Transport control: Most RNA has to go out to the cytoplasm to perform its function. For this they have to cross the pores of the nuclear membrane, where you can select the RNAs that will be transported and those that will not.
• Stability control: The half-life of RNA can be regulated by the expression of RNAs or mRNA stabilizing proteins in the cytoplasm.
• Translational control: It is exercised on the frequency with which the mRNAs begin to be translated. It can also affect the frequency with which proteins mature and the availability of enzymatic effectors.
Answer:
B- Most of the glucose 6-phosphate enters the pentose phosphate pathway.
Explanation:
Since the cell requires much more ribose 5- phosphate than NADPH, then it would lead the glucose 6-phosphate down the oxidative phosphate pathway to create ribulose 5-phosphate, which can be isomerized to ribose 5-phosphate depending on the cell state.
