biochem glycolysis

Question 1

a series of 10 enzyme-catalyzed reactions by which glucose is oxidized to two molecules of pyruvate.

Answer 1

Glycolysis:

Question 2

• During glycolysis, there is net conversion of

Answer 2

2ADP to 2ATP

Question 2

phosphorylation of α-D-glucose.

Answer 2

• reaction 1

Question 2

isomerization of glucose 6-phosphate to fructose 6-phosphate

Answer 2

• reaction 2:

Question 3

• This isomerization is most easily seen by considering the open-chain forms of each monosaccharide; it is one keto-enol tautomerism followed by another

Answer 3

glycolysis- Rexn 2

Question 4

cleavage of fructose 1,6-bisphosphate to two triose phosphates

Answer 4

• reaction 4

Question 5

: phosphorylation of fructose 6- phosphate.

Answer 5

reaction 3

Question 6

: isomerization of triose phosphates

Answer 6

• reaction 5

Question 7

• reaction 5 is Catalyzed by

Answer 7

phosphotriose isomerase

Question 8

• Reaction in reaction 5 involves two successive

Answer 8

keto-enol tautomerizations.

Question 9

oxidation of the -CHO group of D- glyceraldehyde 3-phosphate.

Answer 9

• Reaction 6

Question 10

• The product contains a phosphate ester and a high- energy mixed carboxylic-phosphoric anhydride.

Answer 10

• Reaction 6

Question 11

transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP.

Answer 11

• Reaction 7

Question 12

isomerization of 3-phosphoglycerate to 2-phosphoglycerate

Answer 12

• Reaction 8

Question 13

phosphate transfer to ADP

Answer 13

• Reaction 10

Question 14

dehydration of 2-phosphoglycerate

Answer 14

• Reaction 9:

Question 15

is most commonly metabolized in one of three ways, depending on the type of organism and the presence or absence of O2

Answer 15

• Pyruvate

Question 16

In vertebrates under anaerobic conditions, the most important pathway for the regeneration of NAD+

Answer 16

reduction of pyruvate to lactate

Question 17

is a tetrameric isoenzyme consisting of H and M subunits; H4 predominates in heart muscle, M4 in skeletal muscle

Answer 17

• Lactate dehydrogenase (LDH

Question 18

While reduction to lactate allows glycolysis to continue, it ____ the concentration of _______ and also of _______

Answer 18

increases

lactate

H+ in muscle tissue

Question 19

• When blood lactate reaches about________, muscle tissue becomes almost completely exhausted.

Answer 19

0.4 mg/100 mL

Question 20

• Under aerobic conditions, pyruvate undergoes

Answer 20

oxidative decarboxylation.

Question 21

decarboxylation.
* The carboxylate group is converted to

Answer 21

CO2.

Question 22

• The remaining two carbons from the decarboxylation are converted to the

Answer 22

• The remaining two carbons are converted to the

Question 23

* Glycerol enters glycolysis via

Answer 23

dihydroxyacetone phosphate.

Question 24

are a highly reduced form of carbon.

Answer 24

* Hydrocarbon chains

Question 25

a series of five enzyme-catalyzed reactions that cleaves carbon atoms two at a time from the carboxyl end of a fatty acid.

Answer 25

* β-Oxidation

Question 26

the fatty acid is activated by conversion to an acyl CoA; activation is equivalent to the hydrolysis of two high-energy phosphate anhydrides.

Answer 26

* Reaction 1:

Question 27

oxidation of the α,β carbon-carbon single bond to a carbon-carbon double bond

Answer 27

* Reaction 2:

Question 28

hydration of the C=C double bond to give a 2° alcohol.

Answer 28

Reaction 3

Question 29

oxidation of the 2°alcohol to a ketone.

Answer 29

* Reaction 4:

Question 30

cleavage of the carbon chain by a molecule of CoA-SH.

Answer 30

* Reaction 5

Question 31

* This cycle of reactions is then repeated on the shortened fatty acyl chain and continues until the entire fatty acid chain is degraded to

Answer 31

acetyl CoA

Question 32

* β-Oxidation of unsaturated fatty acids proceeds in the same way, with an extra step that

Answer 32

isomerizes the cis double bond to a trans double bond

Question 33

: acetone, β-hydroxybutyrate, and acetoacetate;

Answer 33

* Ketone bodies

Question 34

* are formed principally in liver mitochondria

Answer 34

* Ketone bodies

Question 35

* Formation occurs when the amount of acetyl CoA produced is excessive compared to the amount of oxaloacetate available to react with it and take it into the TCA

Answer 35

* Ketone bodies:

Question 36

NH2 groups move freely by

Answer 36

transamination

Question 37

* Pyridoxal phosphate forms an

Answer 37

imine

Question 38

* Rearrangement of the imine gives an

Answer 38

isomeric imine

Question 39

* Hydrolysis of the isomeric imine gives an

Answer 39

α-ketoacid and pyridoxamine

Question 40

* nitrogens to be excreted are collected in

Answer 40

glutamate,

Question 41

* nitrogens to be excreted are collected in glutamate, which is oxidized to

Answer 41

α-ketoglutarate and NH +

Question 42

a cyclic pathway that produces urea from CO2 and NH +.

Answer 42

Urea cycle

Question 43

* The breakdown of amino acid carbon skeletons follows two pathways

Answer 43

* glucogenic amino acids * ketogenic amino acids

Question 44

: those whose carbon skeletons are degraded to pyruvate or oxaloacetate, both of which may then be converted to glucose by gluconeogenesis.

Answer 44

* glucogenic amino acids:

Question 45

those whose carbon skeletons are degraded to acetyl CoA or acetoacetyl CoA, both of which may then be converted to ketone bodies

Answer 45

* ketogenic amino acids

Question 46

* When red blood cells are destroyed

Answer 46

* heme is converted to bilirubin. * bilirubin enters the liver via the bloodstream and is then transferred to the gallbladder where it is stored in the bile and finally excreted in the feces.