[مجهول1408]

(1) Would you expect the free energy of hydrolysis of acetoacetyl-coenzyme A (see
diagram) to be greater than, equal to, or less than that of acetyl-coenzyme A? Provide achemical rationale for your answer.

Answer: Hydrolysis of acetyl-coenzyme A produces free coenzyme A and acetate whereas
hydrolysis of acetoacetyl-coenzyme A releases acetoacetate and coenzyme A. Acetate is relatively stable; however, acetoacetate is unstable and will break down to acetone and CO2. Thus, the instability of one of the products of hydrolysis of acetoacetyl-coenzyme A, namely acetoacetate, will make the reverse reaction (i.e., production of acetoacetyl-coenzyme A) unlikely.
Furthermore, the terminal acetyl group of acetoacetyl-coenzyme A is electron-withdrawing in
nature and will destabilize the thiol ester bond of acetoacetyl-CoA. Thus, the free energy of
hydrolysis of acetoacetyl-coenzyme A is expected to be greater than that of acetyl-coenzyme A
and in fact, the free energy of hydrolysis is -43.9 kJ/mol for acetoacetyl-CoA and -31.5 kJ/mol for acetyl-CoA.

(2)Write a full report the ATP molecule:

1-How it was discovered?

Answer: ATP was first discovered by the German chemist Karl Lohmann in 1929.

2_How is detrmined quantity?

Answer:

When ATP was determined in a sample of the preparation by the enzymatic (hexokinase) method with subsequent determination of ATP according to the decrease in acid-labile phosphorus, by the spectrophotometrical method, the radioenzymatic method, and by paper chromatography, the various data were in agreement with each other. The data obtained by analysis of the ATP preparation according to 7''-hydrolyz-able phosphorus were high in comparison with the data obtained by the other methods.

3_function?

Answer:

The ATP is used for many cell functions including transport work moving substances across cell membranes. It is also used for mechanical work, supplying the energy needed for muscle contraction. It supplies energy not only to heart muscle (for blood circulation) and skeletal muscle (such as for gross body movement), but also to the chromosomes and flagella to enable them to carry out their many functions. A major role of ATP is in chemical work, supplying the needed energy to synthesize the multi-thousands of types of macromolecules that the cell needs to exist.

ATP is also used as an on-off switch both to control chemical reactions and to send messages. The shape of the protein chains that produce the building blocks and other structures used in life is mostly determined by weak chemical bonds that are easily broken and remade. These chains can shorten, lengthen, and change shape in response to the input or withdrawal of energy. The changes in the chains alter the shape of the protein and can also alter its function or cause it to become either active or inactive.
The ATP molecule can bond to one part of a protein molecule, causing another part of the same molecule to slide or move slightly which causes it to change its conformation, inactivating the molecule. Subsequent removal of ATP causes the protein to return to its original shape, and thus it is again functional. The cycle can be repeated until the molecule is recycled, effectively serving as an on and off switch (Hoagland and Dodson, 1995, p.104). Both adding a phosphorus (phosphorylation) and removing a phosphorus from a protein (dephosphorylation) can serve as either an on or an off switch.

4_ On what form it is present inside the cell?

Answer:

In the form of energy

A crucial difference between prokaryotes and eukaryotes is the means they use to produce ATP. All life produces ATP by three basic chemical methods only: oxidative phosphorylation, photophosphorylation, and substrate-level phosphorylation (Lim, 1998, p. 149). In prokaryotes ATP is produced both in the cell wall and in the cytosol by glycolysis.

5_How much of it in a typical cell?

Answer:

in a typical cell is found to be ~1mM for ATP, 10μm for ADP and ~1mM for phosphate .

6_How much of it is needed for normal daily in humans?

Answer:

About 1020 molecules per second, equivalent to a turnover rate of ATP of 65 kg per day. This can vary depending on activity. Here is a website that has bolic rates and the use of ATP that may help you find an approximate figure

(3)What is the relationship between NAD+ and vitamin B1 ?

In Both NAD And FAD, The Vitamin B Portion Of The Molecule Is The Active Part. Is This Also True For CoA?

Vitamins, the coenzymes derived from them, the type of reactions in which they participate, and the type of coenzym.

VITAMINS AND COENZYMES
Vitamin
Coenzyme
Reaction type
Coenzyme class

B 1 (Thiamine)
TPP
Oxidative decarboxylation
Prosthetic group
B 2 (Riboflavin)
FAD
Oxidation/Reduction
Prosthetic group
B 3 (Pantothenate)
CoA - Coenzyme A
Acyl group transfer
Cosubstrate
B 6 (Pyridoxine)
PLP
Transfer of groups to and from amino acids
Prosthetic group
B 12 (Cobalamin)
5-deoxyadenosyl cobalamin
Intramolecular rearrangements
Prosthetic group
Niacin
NAD +
Oxidation/Reduction
Cosubstrate
Folic acid
Tetrahydrofolate
One carbon group transfer
Prosthetic group
Biotin
Biotin
Carboxylation
Prosthetic group

Reaction of pyruvate dehydrogenase complex (PDC)

Thiamine pyrophosphate (TPP) is an important cofactor of pyruvate dehydrogenase complex, and it is important in citric acid cycle.

(4)NAD+ has two ribose units in its structure; FAD are has a ribose and a ribitol. What is the relationship between these molecules?

NAD+ and FAD+ receive electrons and H+ in respiration and carry these to the electron transport chain on the inner metochondoria membrane.

NADH2 feeds into complexI and the lower energy molecule FADH2 feeds into complexII lower down the chain.

Approximately 3ATP are made per NADH2 and 2ATP made per FADH2.

Ribitol or adonitol is formed by reduction of ribose .