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108 Cards in this Set

  • Front
  • Back

What is the name of the starting material of the citric acid cycle?

Acetyl-coenzyme A

The citric acid cycle begins with the reaction between?

acetyl-CoA and the four-carbon oxaloacetate to form six-carbon citric acid (Citrate)

During the eight reactions that take place, for every molecule of acetyl-CoA the cycle produces?

2CO2 + 3 (NADH + H+) + 1 FADH2 + HS-CoA + 1GTP(ATP)

Stage 1 reactions and product

Acetyl-CoA (2C) bonds with Oxaloacetate (4C) and produces Citrate (6C)


What releases coenzyme A in Stage 1?

A water molecule attacking the Acetyl releases the CoA

Stage 2 turns what into what product?

Citrate (6C) ---> Isocitrate (6C)



Isomerization

Citrate Summary

Stage 2


3 degree alcohol


Isomerization


Creates an isomer Isocitrate a 2 degree alcohol by a water molecule that is removed from the citric acid and then put back on in another location.



Isocitrate Summary

Stage 3


2 degree alcohol


Oxidation and Decarboxylation


2 events occur:


NAD ---> NADH + H+


The enzyme isocitrate dehydrogenase catalyzes the oxidation of the –OH group at the 4' position of isocitrate to yield an intermediate which then has a carbon dioxide molecule removed from it to yield alpha-ketoglutarate.


Release CO2

Stage 3 product?

Isocitrate (6C) ----> alpha - ketoglutarate (5C)




Oxidation and Decarboxylation

Alpha - ketoglutarate Summary

Stage 4


Oxidation and Decarboxylation


5 Carbon


Ketone


loses a carbon dioxide molecule and coenzyme A is added in its place.


NAD ---> NADH + H+


release of CO2



Succinyl-CoA Summary

Stage 5


Hydrolysis


4 Carbon


GTP synthesized


Releases coenzyme CoA


In this reaction, a free phosphate group first attacks the succinyl-CoA molecule releasing the CoA. After the phosphate is attached to the molecule, it is transferred to the GDP to form GTP. The resulting product is the molecule succinate

Stage 4 produces what?

Alpha - ketoglutarate (5C) ---> Succinyl-CoA (4C)




Oxidation and Decarboxylation

Stage 5 produces what?

Succinyl-CoA (4C) ---> Succinate (4C)




Hydrolysis

Hydrolysis

the chemical breakdown of a compound due to reaction with water.

decarboxylation

is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2)

Redox reaction

Because both reduction and oxidation are going on side-by-side, this is known as a redox reaction




Oxidation is gain of oxygen


Reduction is loss of oxygen




Oxidising agents give oxygen to another substance


Reducing agents remove oxygen from another substance

Stage 6 products

Succinate (4C) ---> Fumarate (4C)




Oxidation

Succinate Summary

Stage 6


Oxidation


4 Carbon


The enzyme succinate dehydrogenase catalyzes the removal of two hydrogens from succinate


FAD ---> FADH2 (as it takes H from succinate)


Makes a (C = C) bond


Produces fumarate





Fumarate Summary

Stage 7


Hydration


4 Carbon


the addition of a water molecule to the fumarate in the form of an –OH group to yield the malate

Stage 7 produces

Fumarate (4C) ---> Malate (4C)




Hydration

Malate Summary

Stage 8


Oxidation


4 Carbon


regenerate oxaloacetate by oxidizing malate

Order of Citric Acid Cycle Reactions

1 - aceytyl-CoA + oxaloacetate


2 - citrate


3 - isocitrate


4 - alpha-ketoglutarate


5 - succinyl-CoA


6 - succinate


7 - fumarate


8 - malate ---> oxaloacetate



Order of reactions that occur with each stage in the citric acid cycle

1 - formation of citrate (coupling)


2 - isomerization


3 - oxidation and decarboxylation (redox)


4 - oxidation and decarboxylation (redox)


5 - hydrolysis


6 - oxidation (redox)


7 - hydration


8 - oxidation (redox)

4 Carbons?

succinyl-CoA


succinate


fumarate


malate


oxaloacetate

6 Carbons?

Citrate


Isocitrate

The initial stage of the digestion of protein is catalyzed by an enzyme called ________.

pepsin

The digestion of protein begins in the ________.

stomach

An enzyme that can facilitate the breakdown of amylose into smaller units is ________.

amylase

Digestion of carbohydrates begins in the ________.

mouth

The components of ATP are ________.

adenine, ribose, and three phosphate groups

The first stage of catabolism is ________.

digestion of large molecules

Most of the energy in the typical animal cell is produced in the ________.

mitochondria

How many main stages of catabolism are there?

3

What stage of metabolism involves the conversion of small molecules to CO2, H2O, and energy?

Oxidation to CO2, H2O, and energy for ATP synthesis

What is meant by a catabolic reaction in metabolism?

A reaction which breaks apart large molecules, releasing energy.

What is meant by an anabolic reaction in metabolism?

An anabolic reaction uses energy in the cell to build large molecules needed by the cell.

Why is ATP considered an energy-rich compound?

The hydrolysis of the phosphodiester bond in ATP releases energy that is sufficient for energy-requiring processes in the cell.

The digestion of fats begins where?

in the small intestine

Identify coenzyme with riboflavin as a component

FAD

Identify coenzyme with Adenine as a component

NAD+


FAD

Identify coenzyme with aminoethanethiol as a component

coenzyme A

If there are no reactions in the citric acid cycle that use oxygen, O2, why does the cycle operate only in aerobic conditions?

The oxidized coenzymes NAD+ and FAD needed for the citric acid cycle are regenerated by the electron transport system.

What reduced coenzymes provide the electrons for electron transport?

NADH


FADH2

What products of the citric acid cycle are needed for the electron transport chain?

NADH


FADH2

What compounds are needed to start the citric acid cycle?

The citric acid cycle begins by combining acetyl CoA and oxaloacetate.

Why is the citric acid cycle considered to be a metabolic cycle?

In the citric acid cycle, oxaloacetate is regenerated, which is available to pick up acetyl CoA and start the cycle again.

Where in the cell are fatty acids normally oxidized?

mitochondria

Where in the cell does the citric acid cycle take place?

mitochondria

Which reaction(s) of the citric acid cycle involve(s) a direct phosphate transfer?

reaction 5


This is the only time in the cycle that ATP is produced by a direct transfer of phosphate. Used to add a phosphate group to ADP to form ATP after GTP undergoes hydrolysis

Which reactions of the citric acid cycle involve oxidation and decarboxylation?

reaction 3 & 4

Which reactions of the citric acid cycle involve a hydration reaction?

reaction 7

Which reactions of the citric acid cycle reduce NAD+?

reaction 3,4,8

Which reactions of the citric acid cycle reduce FAD?

reaction 6

Oxidative phosphorylation

synthesis of ATP from ADP + P, using energy generated by the oxidation reactions during electron transport

Choose an equation for the hydrolysis of ATP to ADP.

ATP + H2O → ADP + Pi + 7.3

Identify coenzyme with pantothenic acid as a component

coenzyme A

Identify coenzyme with niacin as a component

NAD+

Identify coenzyme with ribitol as a component

FAD

The energy released during electron transport is used to produce ________.

ATP

In electron transport, NADH and FADH2 are used to provide ________.

electrons and hydrogen ions

In electron transport, the synthesis of ATP from ADP + Pi is called ________.

oxidative phosphorylation

The last reaction in the citric acid cycle converts malate to ________.

oxaloacetate

In reaction 7 of the citric acid cycle, fumarate is converted to malate in a ________ reaction.

hydration

In the dehydrogenation of succinate to fumarate in the citric acid cycle, the coenzyme used is ________.

FAD

Reaction 5 of the citric acid cycle is the hydrolysis of succinyl-CoA. In this reaction, ________.

the energy released is used to make GTP

The citric acid cycle reaction that removes the first CO2molecule is a(n) ________.

oxidation and decarboxylation

In stage three of catabolism, the overall result is to release ________.

carbon dioxide and energy

Which of the following compounds in the citric acid cycle undergoes oxidation and decarboxylation?

isocitrate

What coenzyme(s) is(are) used in the citric acid cycle?

NAD & FAD

FAD is a coenzyme which usually participates in ________.

formation of carbon-carbon double bonds

NAD+ participates in reactions that produce ________

C=O bond

In biochemical systems, the term reduction often refers to ________.

a gain of hydrogen or electrons by a compound

What is the purpose of digestion in stage 1?

To break down the large molecules in food into smaller compounds that can be absorbed by the body.

Which of the metabolic pathways can occur in the absence of oxygen

glycolysis

The middle stage of catabolism is the point at which

acetyl CoA is produced

Protein synthesis takes place

on the ribosomes

The main compound used to release energy for metabolism is

adenosine triphosphate (ATP)

The final products of catabolic reactions are

carbon dioxide, water, and ammonia

Coenzyme A is a molecule whose function is to

acitvate acyl groups for reaction

An enzyme that can facilitate the breakdown of starch into smaller units is

amylase

When combined with the electron transport chain, one turn of the citric acid cycle produces ____ ATP

12 ATP

The citric acid cycle is used in the oxidation of

glucose, fatty acids and proteins

IN the chemiosmotic model of oxidative phosphorylation, ATP is sythesized as

H+ flows through ATP synthase

The components of the electron transport chain do NOT include

acetyl CoA

In the electron transport chain, the oxidied product from the reaction of FMN + NADH + H+ is

NAD+

The electron carrier ______ provides 2 ATP via the electron transport chain

FADH2

In stage three of metabolism, the overall result is to release

carbon dioxide and energy

In the dehydrogenation of succinate to fumarate in the citric acid cycle, the coenzyme used is

FAD

In step 7 of the citric acid cycle, fumarate is converted to malate by a ______ reaction

hydration

The compounds in electron transport that remove hydrogen ions and electrons from NADH are classified as

electron carriers

One example of an electron carrier in the respiratory chain is

coenzyme Q

In the chemiosmotic model, protons circulate through a protein complex called

ATP synthase

In the activation of a fatty acid, energy from the hydrolysis of ATP is used to

join the fatty acid to CoA

The digestion of fats begins when the fat globules are

emulsified by bile salts

Fatty acids and glycerol are produced from the metabolism of

lipids

The action of pancreatic lipase on tricylglycerols produces

monoacylglycerols and free fatty acids

A chylomicron is a

transport lipoprotein

The enzymes that break down triacylglycerols into fatty acids and glycerol are called

lipases

The 2-carbon segments removed from a fatty acid during metabolism are used to form

acetyl CoA

The 2-carbon units obtained by degradation of a fatty acid are further metabolized in

the citric acid cycle

Each acetyl CoA produces _____ ATP in the citric acid cycle

12

This is the term that refers to all of the chemical reactions in living cells

metabolism

The energy for most energy-requiring reactions in the cells of the body is obtained by the hydrolysis of ____

ATP

Most of the energy in our bodies is stored in the form of

triacylglycerols

Hydrolysis of sucrose takes place primarily in the

small intestine

The process that makes ATP using energy from the electron transport chain

oxidative phosphorylation

The carrier of acetyl groups

coenzyme A

CoA combines with this to form succinyl CoA in the krebs cycle.

Alpha-ketogluterate