Metabolic Systems and Blood Glucose

Question 1

What is metabolism?

Answer 1

The sum of all the chemical reactions that occur in a living organism. The goal is to supply all the needs of every cell

Question 2

What are the two types of metabolic pathways?

Answer 2

anabolic

catabolic

Question 3

What is the difference between digestion and metabolism?

Answer 3

digestion of dietary components (fuels, vitamins, minerals, xenobiotics) leads to cell compounds that are stored or further broken in metabolic pathways

Question 4

What is anabolism?

Answer 4

aka Biosynthetic pathways Using energy to form larger molecules from smaller precursors

Question 5

What is catabolism?

Answer 5

aka degradative pathways; they breakdown of larger molecules into small molecules

Question 6

What is the rate-limiting step?

Answer 6

slowest step in a pathway that is often a regulatory enzyme and is irreversible

Question 7

What is the committed step?

Answer 7

The first irreversible step unique to a pathway

Question 8

what is Metabolic Homeostasis?

Answer 8

when tissue needs are balanced by availability of a particular fuel

Question 9

What maintains metabolic homeostatsis?

Answer 9

blood level of nutrient

Hormone level

Nerve impulses

Question 10

T or F: there is at least one irreversible step in every pathway

Answer 10

True

Question 11

What are some defining characteristics of metabolic and catabolic pathways?

Answer 11

They are:

• linked
• regulated
• enzyme catalyzed
• irreversible (but may contain many reversible steps)

Question 12

What are four types of metabolic pathways?

Answer 12

1. linear
2. branched
3. Cyclic
4. Cascade/ amplification

Question 13

What is a linear pathway?

Answer 13

Contains one substrate and one product

Question 14

What is a cofactor?

Answer 14

required for metabolic pathways (derived from vitamins)

e.g. Niacin, NAD, riboflavin FAD, thiamin, TPP, folic acid, THF, vitamin B12, biotin, vitamin C, vitamin K, vitamin A, mineral

Question 15

What are the two types of cofactors?

Answer 15

coenzymes and prosthetic groups

Question 16

what is a coenzyme?

Answer 16

a non-protein substrate often derived from a vitamin

Question 17

What is a prosthetic group?

Answer 17

metal derivative typically

binds tightly to protein

Question 18

What is the fate of food, vitamins, and drugs that are broken down into compounds in the cell?

Answer 18

They can be used in synthesis of macromolecules or oxidized in catabolic pathways and be used as fuel (ATP)

Question 19

What are some examples of macromolecules that serve as fuel stores?

Answer 19

triacylglycerols, glycogen, and protein

Question 20

What kind of reaction is associated with catabolic processes?

Answer 20

oxidation which is used to synthesize ATP

Question 21

How can ATP be hydrolyzed so that more energy is extracted from the molecule?

Answer 21

ATP –> AMP + 2 PPi

Question 22

Urea is a byproduct of what type of catabolic process?

Answer 22

Protein breakdown

Question 23

T or F: for high energy molecules like Phosphoenolpyruvate, ATP and G6P the equilibrium lies toward hydrolysis

Answer 23

T: they all have a negative ∆G

-the more negative, the more hydrolysis is favored

Question 24

Where is most of the oxygen in a cell consumed and what is it used for?

Answer 24

• mitochondria

- ATP synthesis which is needed for most synthetic processes in the cell and for pumps

Question 25

What step of metabolic pathways is often regulated?

Answer 25

First

Question 26

What are common methods of control in metabolic pathways?

Answer 26

• allosteric control
• feedback inhibition
• Reversible covalent modifications (aka phosphorylation)

Question 27

What are reactions called that are common to many tissues?

Answer 27

housekeeping reactions

Question 28

What is the relationship between ATP generating and ATP consuming pathways in the cell?

Answer 28

• Its a reciprocal relationship, as the amount of ATP increases (energy charge near 1), the ATP generating pathways shut down and ATP consuming pathways start up

Question 29

What is stage one of glycolysis?

Answer 29

breakdown of large macromolecules to simple subunits

Question 30

What is stage two of glycolysis?

Answer 30

Breakdown of simple subunits to Acetyl CoA accompanied by production of limited amounts of ATP and NADH

Question 31

What is stage three of glycolysis?

Answer 31

Complete oxidation of Acetyl CoA to H20 and CO2 in mitochondrion to make a lot of ATP

Question 32

What are the major uses of ATP in the resting state (in order)?

Answer 32

1) Protein synthesis
2) Na/K ATPase
3) Ca2+ ATPase
4) Gluconeogenesis

Question 33

Are all reactions of metabolic pathways enzyme catalyzed?

Answer 33

Yes

Question 34

T or F. Pathways are irreversible (ΔG is negative), but individual steps may be reversible or irreversible. There is at least one irreversible step in every pathway.

Answer 34

T

Question 35

Most of the energy stored in chemical bonds of food is lost as what?

Answer 35

heat

Only some of the energy can be converted to useful forms of energy to drive anabolic pathways in synthesis, or maintain cell integrity (ion pumps, transport, etc.).

Question 36

How are pathways most commonly regulated?

Answer 36

regulating the activity of enzymes or the amount of an enzyme, or both.

Allosteric control and feedback inhibition.

Question 37

Do Allosteric enzymes usually catalyze irreversible or reversible steps?

Answer 37

irreversible

Question 38

Does each tissue has its own unique metabolism?

Answer 38

Yes.

Many reactions are common to many tissues (housekeeping reactions), others are tissue specific.