DNA strands are antiparallel because of phosphodiester bonds. These bonds occur when two strands of DNA join together.
DNA strands form when a phosphate group on one strand of DNA bonds with a hydroxyl group on the other strand of DNA. This type of bond is strong enough to hold the two strands together, yet weak enough to allow the strands to be separated. This allows for the strands of DNA to be pulled apart during replication. Additionally, hydrogen bonds between complementary bases on the two strands also help to keep the strands in their antiparallel orientation. Hydrogen bonds are weaker than phosphodiester bonds, but still, serve to help keep the strands in place. Together, these bonds help keep the strands of DNA antiparallel and help to ensure that DNA is properly replicated during cellular processes.
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the lipid-containing outer envelope surrounding the viral capsid of many animal viruses is derived from...
The outer envelope surrounding the viral capsid of many animal viruses is derived from the host cell's lipid bilayer.
This lipid bilayer is the same membrane that encloses the host cell. During the process of viral replication, the capsid and other components of the virus are assembled inside the host cell and a portion of the host cell's membrane is used to form the outer envelope of the virus.
This envelope, along with the capsid, helps to protect the genetic material of the virus, allowing it to be transported to another cell for infection. The envelope also contains viral proteins that aid in the attachment and fusion of the virus to the host cell.
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do not add any more lactose and watch what transpires. note what happens and why this occurs. how could you re-activate the lacz gene?
The lacZ gene is responsible for the enzyme β-galactosidase which breaks down lactose. When no more lactose is added, the lacZ gene is not activated and the β-galactosidase enzyme does not break down lactose. To re-activate the lacZ gene, you would need to add lactose back in so that the β-galactosidase enzyme is activated and lactose is broken down.
Lactose is a disaccharide sugar composed of glucose and galactose, which is found in milk. Lactose can be hydrolyzed into glucose and galactose through the catalytic action of lactase enzymes. This reaction occurs in the small intestine, and the glucose and galactose are then absorbed and used as energy by the body.
When lactose is present, the lac operon is activated, and the genes involved in lactose metabolism are transcribed into messenger RNA. When lactose is absent, the lac operon is turned off, and these genes are not expressed.
To re-activate the lacZ gene, it is necessary to add lactose or a lactose analog such as IPTG to the culture medium. IPTG is an inducer of the lac operon that does not bind to the repressor protein, allowing the genes involved in lactose metabolism to be expressed even in the absence of lactose.
When lactose is present, the lac operon is activated, and the genes involved in lactose metabolism are transcribed into messenger RNA. When lactose is absent, the lac operon is turned off, and these genes are not expressed.
Therefore, if no more lactose is added to the culture medium, the lac operon will turn off, and the genes involved in lactose metabolism will not be expressed. This occurs because the repressor protein binds to the operator site of the operon, preventing RNA polymerase from transcribing the genes involved in lactose metabolism.
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