Metabolic Pathways

Question 1

1 g of carbohydrate is equal to what kcal

Answer 1

1 kcal

Question 2

increases the chemical reaction significantly

Answer 2

catalyst

Question 3

are the biochemicals that come together and interact at the beginning of the
process such that they are converted into one or more different biochemicals

Answer 3

reactants

Question 4

temporary state wherein they become or processed futher

Answer 4

intermediates

Question 5

reactants can become ___ if the next step is a branching point

Answer 5

common intermediates

Question 6

refer to a chemical that participates as one of the starting chemicals in a
chemical reaction that produces other substance(s).

Answer 6

precursor

Question 7

” is used more specifically to refer to a
chemical compound preceding another in a metabolic pathway.

Answer 7

precursor

Question 8

e types of proteins that play an important role in metabolism by catalyzing the
individual reactions in metabolic pathways.

Answer 8

enzymes

Question 9

Enzymes that catalyze the first reaction in a metabolic pathway are sometimes subject to
___ control by the concentration of the end product of the metabolic pathwa

Answer 9

allosteric

Question 10

” is a word used in chemistry generally (not just biochemistry) to refer to chemicals
that affect the rate (speed) of chemical reactions by participating in the reaction(s) but in
such a way that itis not consumed by the reaction itself.

Answer 10

catalyst

Question 11

, the presence of a
___ may be necessary for a reaction to occur to any meaningful extent under certain
conditions

Answer 11

catalyst

Question 12

are compounds that are neither the initial (starting) chemicals in a pathway or
“process”, nor the end-products used directly or secreted by the cell, nor catalysts (that
participate in but are not used-up by the reactions)

Answer 12

intermediates

Question 13

are compounds
that are formed as temporary “steps” in the overall chemical process

Answer 13

intermediates

Question 14

are compounds that occur at branching points in metabolic
pathways.

Answer 14

common intermediates

Question 15

are compounds that are produced by metabolic
reactions that do not go on to participate in a subsequent reaction in the metabolic pathway.

Answer 15

end products

Question 16

The concentration of the end products of a metabolic pathway often regulates the rate of the
reaction that produces them, i.e. effectively a ___ that prevents over-production

Answer 16

feedback loop

Question 17

inhibition or activation of an enzyme by a small regulatory molecule that interacts at a site other than the active site

Answer 17

allosteric control

Question 18

is a form of negative feedback by which metabolic pathways can be controlled.

Answer 18

end product inhibition

Question 19

Some branching points in metabolic pathways are sometimes called

Answer 19

cross-over points

Question 20

s refer to a stage in a metabolic pathway at which an intermediate
(usually a molecule or part of a molecule), could proceed to change in more than one
possible way, i.e. it could follow two or more possible “(metabolic) pathways”.

Answer 20

branching points

Question 21

The “pathway” followed (next change undergone) by the intermediate is usually the one of
most immediate benefit to the cell, that “decision” being determined by the activity of
____ present around the intermediate.

Answer 21

enzyme

Question 22

is a position at which at least two “paths” intersect

Answer 22

junction

Question 23

implies that the intersection is particularly important, i.e.
one at which decisions taken about which on-going paths to follow from that point onwards
may change depending on circumstances and have important consequences.

Answer 23

key junction

Question 24

are substances (usually compounds) that participate in metabolism processes
and are either produced during metabolism reactions or are “constituents of” i.e. parts that
make-up, foods taken into the body - then broken-down via the digestive
processes

Answer 24

metabolites

Question 25

are therefore among the chemicals included in metabolic pathways. They are often intermediates between reactants and end-products.

Answer 25

metabolites

Question 26

metabolites that are molecules that are essential for an organism's growth, development, and reproduction:

Answer 26

primary metabolites

Question 27

metabolites that are organic compounds produced by organisms that are not essential for the organism's growth, development, or reproduction.

Answer 27

secondary metabolites

Question 28

is the descriptive term used to refer to some metabolic pathways or parts of metabolic pathways that take the form of repeated 'cycles' in which product(s) of the individual metabolic reactions in the sequence become the reactants, i.e. the "starting chemicals", for the next metabolic reaction in the sequence.

Answer 28

metabolic cycles

Question 29

metabolic cycles include

Answer 29

Krebs TCA Cycle Calvin cycle Urea cycle

Question 30

" is a point at which many "pathways" meet. These could be routes, wires, lines of communication or similar e.g. as used in the context of air-travel or information technology

Answer 30

hub

Question 31

can therefore be thought of as a location at which many metabolic processes occur, enabling substances such as molecules, e.g. reaction intermediates, to transfer between reaction processes on an as-needed basis.

Answer 31

metabolic hub

Question 32

example of metabolic hubs in the body

Answer 32

krebs TCA cycle liver

Question 33

generally modify biochemicals via a series of small steps (stages in the process) rather than a single chemical reaction

Answer 33

metabolic pathways

Question 34

Minor adjustments can be made to the structure of the molecules. Energy is released / used in manageable quantities. what characteristic of metabolic pathway

Answer 34

metabolic pathways generally modify biochemicals via a series of small steps

Question 35

Many balances - i.e. requirements for specific enzymes - keep the rate of metabolic processes in check. what characteristic of metabolic pathways

Answer 35

each step in a metabolic pathway is a chemical rxn that can catalyze a specific enzyme

Question 36

Benefit: The biochemical reactions at each stage of a metabolic pathway are more likely to proceed (that is, continue to happen) because the products of that particular reaction do not accumulate because they go on to participate in the next step in the metabolic pathway ... which changes them into other biochemical(s). what characteristic of metabolic pathways

Answer 36

chemical equilibrium may never be reached because the products of reactions do not continue to exist in that form due to participation of nexts step

Question 37

one that is not part of a metabolic pathway but is considered entirely on its own - the meaning of "isolated". In that case only a certain proportion of the reactants may be converted into the products of the reaction due to a natural "equilibrium" situation at which a certain proportion of the total matter concerned is in the form of the reactants and a certain (other) proportion in the form of the products of the reaction

Answer 37

isolated chemical rxn

Question 38

Benefit: Accumulation of concentrations of biomolecules that are the reactants of a step in a metabolic pathway can help to increase the rate (i.e. the "speed") of the process. This is related to the above considerations of "equilibrium". what metabolic pathway characteristic

Answer 38

Steps in a metabolic pathway tend to be arranged in physical space such that the product of one reaction is in the right place to become a reactant (or "precursor") in the next step in the sequence.

Question 39

is the metabolic pathway that converts glucose C6H12O6, into pyruvic acid, CH3COCOOH

Answer 39

glycolysis

Question 40

does glycolysis require oxygen?

Answer 40

no

Question 41

an ancient metabolic pathway

Answer 41

glycolysis

Question 42

parallel pathway of glycolysis

Answer 42

pentose phosphate pathway

Question 43

what metabolic pathway, occur in the oxygen-free conditions of the Archean oceans, also in the absence of enzymes, catalyzed by metals

Answer 43

glycolysis pentose phosphate pathway

Question 44

two phases of glycolysis

Answer 44

investment phase yield phase

Question 45

The first step is phosphorylation of glucose by a family of enzymes called ___ to form glucose 6-phosphate (G6P).

Answer 45

hexokinase

Question 46

This reaction consumes ATP, but it acts to keep the glucose concentration low, promoting continuous transport of glucose into the cell through the plasma membrane transporters.

Answer 46

conversion of glucose to glucose 6-phosphate

Question 47

In addition, the conversion of glucose to glucose-6 phosphate blocks the glucose from leaking out because ___

Answer 47

the cell lacks transporters for G6P, and free diffusion out of the cell is prevented due to the charged nature of G6P

Question 48

why free diffusion of glucose 6-phosphate is not possible

Answer 48

charged

Question 49

Glucose may alternatively be formed from the ____ or hydrolysis of intracellular starch or glycogen.

Answer 49

phosphorolysis

Question 50

Glucose may alternatively be formed from the phosphorolysis or hydrolysis of intracellular ___ or ___.

Answer 50

starch oxygen

Question 51

is a biochemical process that breaks down chemical bonds in a compound using inorganic phosphate

Answer 51

phosphorolysis

Question 52

In animals, an isozyme of hexokinase called ___ is also used in the liver, which has a much lower affinity for glucose (Km in the vicinity of normal glycemia), and differs in regulatory properties

Answer 52

glucokinase

Question 53

The different substrate affinity and alternate regulation of this enzyme are a reflection of the role of the liver in maintaining blood sugar levels.

Answer 53

glucokinase

Question 54

G6P is then rearranged into fructose 6-phosphate (F6P) by what enzyme

Answer 54

glucose phosphate isomerase

Question 55

can also enter the glycolytic pathway by phosphorylation at this point.

Answer 55

fructose

Question 56

The change in structure is an ____ , in which the G6P has been converted to F6P

Answer 56

isomerization

Question 57

This reaction is freely reversible under normal cell conditions what step in glycolysis

Answer 57

conversion of F6P to G6P

Question 58

The change in structure is an isomerization, in which the G6P has been converted to F6P. The reaction requires an enzyme, phosphoglucose isomerase, to proceed. This reaction is freely reversible under normal cell conditions. However, it is often driven forward because of a low concentration of ___

Answer 58

F6P

Question 59

under conditions of high F6P concentration, this reaction readily runs in reverse. This phenomenon can be explained through what principle

Answer 59

Le Chatelier principle

Question 60

Isomerization to a keto sugar is necessary for ____stabilization in the fourth reaction step

Answer 60

carbanion

Question 61

. Because the reaction catalyzed by _____ 1 (PFK-1) is coupled to the hydrolysis of ATP (an energetically favorable step)

Answer 61

phosphofructokinase

Question 62

rate limiting step in glycolysis, a key regulatory point

Answer 62

phosphofructokinase coupled with the hydrolysis of ATP

Question 63

s necessary to allow the formation of two charged groups (rather than only one) in the subsequent step of glycolysis, ensuring the prevention of free diffusion of substrates out of the cell.

Answer 63

second phosphorylation event

Question 64

The same reaction can also be catalyzed by pyrophosphate-dependent ____ (PFP or PPi-PFK), which is found in most plants, some bacteria, archea, and protists, but not in animals

Answer 64

phosphofructokinase

Question 65

phosphofructokinase uses what phosphate donor instead of ATP

Answer 65

pyrophosphate

Question 66

is the conversion using phosphofructokinase reversible?

Answer 66

yes

Question 67

Destabilizing the molecule in the previous reaction allows the hexose ring to be split by aldolase into two triose sugars: dihydroxyacetone phosphate (a aldose/ketose), and glyceraldehyde 3-phosphate (an aldose/ketose)

Answer 67

ketose aldose

Question 68

two classes of aldolases

Answer 68

class I class II

Question 69

aldolases present in animals nad plants

Answer 69

aldolases I

Question 70

aldolases present in fungi and bacteria

Answer 70

class II aldolases

Question 71

is a glycolytic enzyme that catalyzes the conversion of fructose 1-6-diphosphate to glyceraldehyde 3-phosphate and dihydroxy-acetone phosphate via the glycolysis metabolic pathway

Answer 71

aldolase

Question 72

The resulting carbanion is stabilized by the structure of the carbanion itself via ___ charge distribution and by the presence of a charged ion prosthetic group.

Answer 72

resonance

Question 73

rapidly interconverts dihydroxyacetone phosphate with glyceraldehyde-3-phosphate (GADP) that proceeds further into glycolysis.

Answer 73

triosephosphate isomearase

Question 74

The second half of glycolysis is known as the

Answer 74

pay-off phase

Question 75

yield of pay-off phase of glucose

Answer 75

2 NADH 4 ATP

Question 76

The aldehyde groups of the triose sugars are oxidized/reduced, and inorganic phosphate is added to them, forming 1,3- bisphosphoglycerate.

Answer 76

oxidized

Question 77

Hydrogen atom balance and charge balance are both maintained because the phosphate (Pi) group actually exists in the form of a h

Answer 77

hydrogen phosphate anion

Question 78

an anion akin to inorganic phosphate may replace phosphate as a substrate to form 1-arseno-3- phosphoglycerate.

Answer 78

arsenate

Question 79

As a consequence of bypassing this step, the molecule of ATP generated from 1-3 bisphosphoglycerate in the next reaction will not be made, even though the reaction proceeds. As a result, arsenate is an ___ of glycolysis

Answer 79

uncoupler

Question 80

This step is the enzymatic transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP by

Answer 80

phosphoglycerate kinase

Question 81

what enzyme is used to turn G3P to 1,3-bisphosphoglycerate

Answer 81

gylceraldehyde 3-phoshpate dehydrogenase

Question 82

. This step, one of the two substrate-level phosphorylation steps,requires ADP; thus, when the cell has plenty of ATP (and little ADP), this reaction does not occur.

Answer 82

glycolysis reaching a breakeven point of 2 ATP molecules synthesized

Question 83

enzyme to convert 1,3-bisphosphoglycerate to 3-phosphoglycerate

Answer 83

phosphoglycerate mutase

Question 84

next converts 2-phosphoglycerate to phosphoenolpyruvate

Answer 84

enolase

Question 85

This reaction is an elimination reaction involving an elimination mechanism.

Answer 85

reaction of 2-phosphoglycerate to phosphoenolpyruvate

Question 86

A final substrate-level phosphorylation now forms a molecule of pyruvate and a molecule of ATP by means of the enzyme

Answer 86

pyruvate kinase

Question 87

e, is a series of chemical reactions that release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

Answer 87

citric acid cycle

Question 88

e is used by organisms that respire (as opposed to organisms that ferment) to generate energy, either by anaerobic respiration or aerobic respiration

Answer 88

TCA cycle

Question 89

Its central importance to many biochemical pathways suggests that it was one of the earliest components of metabolism and may have originated abiogenically.

Answer 89

krebs cycle

Question 90

The cycle consumes ___(in the form of acetyl-CoA) and water, reduces NAD+ to NADH, releasing carbon dioxide.

Answer 90

acetate

Question 91

The cycle consumes acetate (in the form of acetyl-CoA) and water, reduces NAD+ to NADH, releasing ___ ___

Answer 91

carbon dioxide

Question 92

In eukaryotic cells, the citric acid cycle occurs in the

Answer 92

matrix of mitochondrion

Question 93

In prokaryotic cells, such as bacteria, which lack mitochondria, the citric acid cycle reaction sequence is performed in the

Answer 93

cytosol

Question 94

In prokaryotic cells, such as bacteria, which lack mitochondria, the citric acid cycle reaction sequence is performed in the cytosol with what gradient

Answer 94

proton gradient

Question 95

The overall yield of energy-containing compounds from the TCA cycle

Answer 95

3 NADH 1 FADH2 one GTP

Question 96

is a key metabolic pathway that connects carbohydrate, fat, and protein metabolism.

Answer 96

citric acid cycle

Question 97

One of the primary sources of acetyl-CoA is from the breakdown of sugars by glycolysis which yield pyruvate that in turn is decarboxylated by the ___ ___ complex generating acetyl-CoA

Answer 97

pyruvate dehydrogenase

Question 98

is the starting point for the citric acid cycle. A

Answer 98

acetyl coA

Question 99

e. Acetyl-CoA may also be obtained from the oxidation of __ ___

Answer 99

fatty acids

Question 100

The citric acid cycle begins with the transfer of a two-carbon acetyl group from acetyl-CoA to the four-carbon acceptor compound (____) to form a six-carbon compound (citrate)

Answer 100

oxaloaceatate

Question 101

The citric acid cycle begins with the transfer of a two-carbon acetyl group from acetyl-CoA to the four-carbon acceptor compound (oxaloacetate) to form a six-carbon compound (____)

Answer 101

citrate

Question 102

The citrate then goes through a series of chemical transformations, losing two carboxyl groups as ___

Answer 102

CO2

Question 103

enzyme for conversion of Oxaloactetate + Acetyl coA + H2O to Citrate + CoA-SH

Answer 103

citrate synthase

Question 104

how many carbons does oxaloacetate have

Answer 104

4C

Question 105

citrate has how many carbons

Answer 105

6C

Question 106

enzyme for Citrate > isocitrate

Answer 106

aconitase

Question 107

enzyme for isocitrate > ketoglutarate

Answer 107

isocitrate dehydrogenase

Question 108

how many carbons does ketoglutarate have

Answer 108

5

Question 109

enzyme for ketoglutarate > succinyl coA

Answer 109

a-ketoglutarate dehydrogenase

Question 110

how many c does succincyl CoA have

Answer 110

4

Question 111

enzyme for succinyl coA to succinate

Answer 111

succinyl CoA synthethase

Question 112

enzyme for succinate > fumarate

Answer 112

succinate dehydrogenase

Question 113

enzyme for fumarate > malate with the help of H2O

Answer 113

fumarase

Question 114

enzyme for malate > oxaloacetate

Answer 114

malate dehydrogenase

Question 115

Mitochondria in animals, including humans, possess ___ succinyl-CoA synthetases: one that produces GTP from GDP, and another that produces ATP from ADP

Answer 115

two

Question 116

what are the products of succinyl coA synthethases in animals

Answer 116

GTP from GDP ATP from ADP

Question 117

. Plants have the type that produces what kind of succincyl coA synthethase

Answer 117

ATP

Question 118

The GTP that is formed by GDP-forming succinyl-CoA synthetase may be utilized by ___ ___ ____to form ATP (the catalyzed reaction is GTP + ADP → GDP + ATP).

Answer 118

nucleoside disphosphate kinase