Answer:
Cell theory is theory instead of law because cell theory doesn't have enough support to become a law
The synthesis of cholesterol is a process that involves over 30 different steps. Which step is the rate-determining step of cholesterol synthesis?1) The conversion of mevalonic acid to isopentenyl pyrophosphate2) The conversion of squalene into squalene 2,3-epoxide by squalene monooxygenase.3) The condensation of two acetyl-CoA molecules to acetoacetyl-CoA by thiolase.4) The conversion of HMG-CoA to mevalonate by HMG-CoA reductase.
Answer:
The conversion of HMG-CoA to mevalonate by HMG-CoA reductase
Explanation:
Cholesterol is one of the steroids found in the cell membranes of the eukaryotes, mainly in animal cells. It has a long fatty acid chain that is derived from the acetyl CoA. Biosynthesis of cholesterol includes four steps. The first step is the condensation reaction that forms mevalonate from the three acetate residues. The mevalonate is a six-carbon substance. It is followed by the formation of the isoprene units from the mevalonate.
The first step of the cholesterol biosynthesis that forms mevalonate from the acetate is a rate-limiting step. First, two molecules of acetyl CoA react to form acetoacetyl-CoA. It is followed by the joining of the third acetyl CoA to form HMG-CoA, a compound with six carbon atoms. The synthesis of the HMG-CoA from acetoacetyl-CoA is catalyzed by the HMG-CoA synthase. The HMG-CoA is then reduced into mevalonate, a reaction catalyzed by HMG-CoA reductase. Here, two molecules of NADPH serve as electron donors.
The pathway of cholesterol biosynthesis is regulated by the concentration of the cholesterol present in the cell and the pancreatic hormones. Accordingly, the expression of the gene encoding HMG-CoA reductase is regulated to determine the rate of the pathway, making this step a rate-determining step.
HMG-CoA reductase is present in two alternative forms: the phosphorylated form is the inactive form while the dephosphorylated form is the active form of the enzyme.
When the cholesterol levels are high, the hormone glucagon triggers the inactive of the enzyme by its phosphorylation. This covalent modification is reversible and the enzyme is dephosphorylated under the influence of hormone insulin when the intracellular cholesterol levels are low. In this way, covalent modification of the enzyme HMG-CoA reductase regulates the cholesterol biosynthesis.
What is it called when scientists carefully examine a new result by someone else in this field of study
its called peer review!
How does the following sentence contribute to the development of the main idea in the article?
This was strong evidence that the innate immune system is responsible for putting farm microbes to good use in the body.
A. It shows the connection between the Amish immune systems and their environment.
B. It develops the idea that the genes you are born with will determine if you get asthma or not.
C. It proves that the Amish are the healthiest group of Americans.
D. It gives an example of how farm microbes can hurt children.
Answer:
B
Explanation:
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If a person has a tidal volume of 550 ml and breathes at a rate of 14 times per minute, what is the minute ventilation rate?
Answer:
The minute ventilation rate = 7.7 Lpm
Explanation:
a) The tidal volume = 550 ml
Respiratory rate = 14 times per minute
Since minute ventilation (VE) is the total volume of gas entering (or leaving) the lung per minute, it is equal to the tidal volume (TV) multiplied by the respiratory rate (f).
This implies that Minute Ventilation = VE = TV x f
= 550 * 14
= 7,700 ml/min.
Therefore, the minute ventilation rate = 7.7 Lpm (7,700/1,000) or 7.7 liters per minute.
b) The ventilation rate is also known as the inhalation rate or breathing rate. It is the amount of air inhaled in a specified time period. Note that at rest, a normal person moves approximately 450 ml/breath * 10 breath/min or 4500 ml/min (4.5 Lpm).
A roller coaster containing four cars is accelerating at -15 m/s2 before it comes to an abrupt stop at the end of the ride. The mass of one car is 200 kg. How much force was exerted on the roller coaster to bring it to a stop
Answer:
F = -3000 N
Explanation:
Given that,
Mass of the car, m = 200 kg
A roller coaster containing four cars is accelerating at -15 m/s²
We need to find the force exerted on the roller coaster to bring it to a stop. Let F is the force.
F = ma
Putting all the values,
F = 200 kg × (-15 m/s²)
= -3000 N
So, the force us 3000 N and it act in opposite direction.
Hurricanes tend to disperse after making landfall because the land is much hotter than the ocean water.
Answer: False
Explanation:
For a Hurricane to keep going it needs to have hot air constantly going up and cold air coming down. When it gets to land, it loses access to the heat and moisture of the sea which is greater than on land. This forces it to weaken and to eventually dissipate.
Therefore, hurricanes disperse after making landfall because land is not as hot as the ocean water.
The cracking of rock due to heat is an example of _______.
a.
erosion
b.
physical weathering
c.
chemical weathering
d.
none of the above
Answer:
Physical weathering
Explanation:
Just did the quiz
Answer: B. physical weathering
Explanation: I can confirm the first person who answered! This answer is correct on edge2020 :)