Answer:
A. The complementary shapes of an enzyme and a substrate
Explanation:
The Lock-and-Key model was made to show how an enzyme's active zone fits a substrate and how they bond together. It correlates just like a lock and a key; you have to have the correct-shaped key in order to open a lock. Same process of thought with the enzymes; you must have the same shape for both in order to bind together,
Glucose level increase, insulin is secreted.
glucose level decrease, glucagon is secreted
Hearing.
The process of hearing starts by pressure waves that are captured by our ears and taken inside the ear by the ear canal reaching firstly the ear drum. The ear drum then vibrates according to the pressure waves that were captured making the acicular (a set of 3 little bones) enter in motion. This vibrations then move from the acicular to the inner ear. Within the inner ear we can find the cochlea which is where this mechanical waves are converted into electrical signals and then passed to the brain. The auditory cortex of the brain then interprets this signals as sounds and gives them meaning.
The nucleus is the part which controls the cell and is semipermeable
DNA is condensed by a certain amount just on its own, just by its own interactions within the DNA molecule,..but whne proteins get involved it gets condensed 30000 fold
<span>what happens is that proteins called histones are like hockey pucks, and DNA wraps around it 1.5 times and then goes to another histone and wraps around that so that it looks like beads on a string (i hope that makes sense, its the only way to describe it) </span>
<span>these histones condense this DNA a lot, and when the histones get methylated then the DNA packs together even closer to get heterochromatin (VERY densely packed DNA)...the theory here is that DNA has a net negative charge due to the phosphate groups in the DNA backbone and doesnt allow the DNA to come together as closely as it could (like charges repel like charges), but when histones are methylated, the negative charge on the DNA is masked by the methyl groups and DNA can come together closer </span>
