Final Amino acid Bio synthesis

Question 1

What are the three efficient solutions to important biochemical problems?

Answer 1

1. obtain nitrogen in a usable form
2. exercise strict stereochemical control
3. restrict AA production only when supplies are very limited

Question 2

Nitrogen in biological systems is ultimately derived from atmospheric N2 through a reductive process called?

Answer 2

Nitrogen Fixation

Question 3

Fixation requires cleavage of the triple bond found in N2 and it is super strong. How is it possible to turn it into NH3, even though it produces unstable intermediates

Answer 3

it requires a specialized catalyst

Question 4

What can be found in root nodules?

Answer 4

Symbiotic nitrogen-fixing bacteria that can carry our nitrogen fixation

Question 5

n biological settings, the reduction of N2 to NH3 is carried out by an enzyme assembly called ?

Answer 5

nitrogenase complex

Question 6

Still, diazotrophic organisms account for only about 60% of N2 fixation on Earth. The remainder occurs through…….. processes or through an industrial reaction called the …… process:

Answer 6

1. photo electric process
2. baer bosch process

Question 6

What is the nitrogenase complex composed of?

Answer 6

reductase- provides high reducing potential electrons
nitrogenase- use electrons to reduce N2 to NH3

Question 7

for nitrogen fixation ATP hydrolysis purpose is to ?

Answer 7

used to lower the kinetic activation barriers to the pathway!

Question 8

what is the term used to describe organisms that are capable of nitrogen fixation

Answer 8

diazotrophic

Question 9

What is the fate of the ammonium ions after fixation?

Answer 9

This ammonium ion is assimilated into glutamate and glutamine, - play critical roles in the biosynthesis of other nitrogen-containing compounds.

Question 10

Amino Acid are Made from

Answer 10

Intermediates of the Citric Acid Cycle and Other Major Pathways

Question 11

TCA we get what metabolites

Answer 11

OAA - asperate and a-Ketogluterate- glutamate

Question 12

In glycolysis we get what metabolites

Answer 12

Pyruvate and 3- Phosphoglycerate

Question 13

glycolysis and pentose phosphate ptwy we get what metabolites

Answer 13

Phosphoenolpyruvate + erythrose 4- phosphate

Question 14

Pentose ptwy we get what metabolites

Answer 14

ribose 5 - phosphate

Question 15

Which amino acids result from the transamination of pyruvate and
oxaloacetate

Answer 15

Alanine and asperate

Question 16

Most microorganisms can synthesize the entire basic set of 20 amino acids. This is not the case for humans, and 9 of the twenty must be taken in adequate dietary supply. These are denoted the essential amino acids:

Answer 16

Histidine
Isoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valine

Question 17

The Biosynthetic Pathways for Essential Amino Acids Are Generally More Involved Than Those of the Nonessential Ones
true or false

Answer 17

true - require more steps

Question 18

when there is an abundant of a- ketoacid’s what is formed through transamination?

Answer 18

Aspartate, Alanine, and Glutamate

Question 19

α-ketoglutarate can be converted into glutamate using free ammonium ion and the enzyme glutamate dehydrogenase.
Once formed, glutamate can serve as an amino group donor for the transamination of?

Answer 19

oxaloacetate and pyruvate

Question 20

What is the most abundant amino acid in cells

Answer 20

glutamate

Question 21

how are glutamine and asparagine synthesized?

Answer 21

1. The formation of asparagine from aspartate (catalyzed by asparagine synthetase) is chemically analogous to the formation of glutamine from glutamate
2. both require ATP hydrolysis

Question 22

How does asperate get to asparagine

Answer 22

catalyzed by asparagine synthetases but uses an acyl-adenylate intermediate

Question 23

Glutamate can serve as an amino group donor for ….

Answer 23

transamination of oxaloacetate and pyruvate

Question 24

The formation of asparagine from aspartate require what intermediate ?

Answer 24

acyl-adenylate intermediate

Question 25

In mammals, the source of ammonium is actually ……., which is hydrolyzed in the enzymatic active site.

Answer 25

glutamine

Question 26

Glutamate is the precursor for

Answer 26

Glutamine, Proline, and Arginine

Question 27

transamination of α-ketoglutarate can give us the formation of ?

Answer 27

glutamate

Question 28

what is Glutamic γ-semialdehyde formed from?

Answer 28

When the Glutamate γ-phosphate group of reacts with ATP it forms an acyl-phosphate intermediate, then reduced NADPH.

Question 29

What are the two metabolic fates of Glutamic γ-semialdehyde

Answer 29

1. An enzymatic dehydration of Glutamic γ-semialdehyde to yield delta 1-pyroline 5-carboxylate, which can be reduced by NADPH to yield proline.
2. transamination by glutamate to produce ornithine then through urea cycle to produce arginine

Question 30

3-Phosphoglycerate is the Precursor for?

Answer 30

Serine, Cysteine, and Glycine

Question 31

3-Phosphoglycerate is an intermediate in what process?

Answer 31

glycolysis

Question 32

The formation of serine is required to generate what ?

Answer 32

cysteine and glycine

Question 33

what is the first step in serine production?

Answer 33

1. 3-phosphoglycerate is NAD+- oxidation to produce 3-phosphohydroxypruvate
2. transamination to yield 3-phosphoserine
3. hydrolysis to serine

Question 34

what must serine interact with in order to get the formation of cysteine and glycine?

Answer 34

new activated group carriers of one-carbon groups

Question 35

tetrahydrofolate and S-Adenosylmethionine, what is their purpose

Answer 35

used as new activated group carriers of one-carbon groups and interact with serine to produce cysteine and glycine

Question 36

The regulation of metabolic flux through pathways of amino acid biosynthesis is regulated both by

Answer 36

enzyme levels
activity level

Question 37

Let’s consider the synthesis of serine. The committed step in this pathway is?

Answer 37

oxidation of 3-phosphoglycerate catalyzed by 3-phosphoglycerate dehydrogenase

Question 38

The E. coli enzyme is a tetramer comprising catalytic and regulatory regions. The binding of serine to a regulatory site causing ?

Answer 38

reduced vmax of enzyme
enzyme bound to four serines is essentially inactive

Question 39

if serine is abundant in the cell, the enzymatic activity is?

Answer 39

blocked and 3-phosphoglycerate can be used for other processes.

Question 40

When considering amino acid biosynthesis, we have encountered several pathways where a common intermediate precursor is ultimately converted into two different products. The regulation of these branched pathways is more complicated because two products must be accounted for. What are the four main strategies for regulation?

Answer 40

1. Feedback inhibition and activation
2. Enzyme multiplicity
3. Cumulative feedback inhibition
4. Reversible covalent modification

Question 41

Sometimes, two pathways are parallel with common intermediates, what helps balance the flux of production?

Answer 41

two pathways with a common intermediate may each be inhibited by their product and activated by the product of the other

Question 42

an example of two pathways with a common intermediates being inhibited by their product and activated by the product of the other.

Answer 42

When threonine is converted into α- ketobutyrate in the committed step, it leads to the synthesis of isoleucine.
The enzyme threonine deaminase is inhibited when the levels of Isoleucine are elevated but activated by valine

Question 43

What is the regulation of enzyme multiplicity ?

Answer 43

In this strategy, a committed step can be catalyzed by two or more enzymes, each with a distinct set of regulatory properties

Question 44

What is an example of enzyme multiplicity

Answer 44

An example of this is the phosphorylation of aspartate in E. coli. committed step of the biosynthesis of methionine and threonine

one enzyme is not subject to feedback inhibition,
another is inhibited by threonine,
the third is inhibited by lysine

Question 45

what is Cumulative feedback inhibition

Answer 45

A common metabolic step can be partly inhibited by each of the final products, acting independently.

Question 46

The activity of glutamine synthetase in E. coli is regulated . The amide group of glutamine is an important nitrogen donor in the biosynthesis of a variety of molecules, including tryptophan, histidine, and carbamoyl phosphate. Each of these endpoints contributes partially to feedback inhibition of the synthetase. this is an example of ?

Answer 46

Cumulative feedback inhibition

Question 47

what is Reversible covalent modification?

Answer 47

a modified form of an enzyme is either more or less active than the unmodified form.

Question 48

glutamine synthetase is regulated by the attachment of an AMP unit to the hydroxyl group of a specific tyrosine in each subunit. This makes it a less active enzyme. This is an example of what type of regulation?

Answer 48

Reversible covalent modification

Question 49

Amino acids can only be precursors for proteins, True of false?

Answer 49

false-many different biomolecules that arise from amino acid precursors.