Lecture 20: Basic Concepts in Metabolism

Question 1

Two opposing streams of chemical reactions

Answer 1

catabolism vs. anabolism

Question 2

Catabolic Pathways

Answer 2

break down macromolecules into smaller molecules, thereby generating both a useful form of energy (energy carriers) for the cell and some of the small molecules that the cell needs as building blocks

Question 3

Anabolic Pathways

Answer 3

Biosynthetic. Pathways use the energy harnessed by catabolism to drive the synthesis of many endogenous macromolecules that form the cell.

Question 4

Amphibolic

Answer 4

both anabolic and catabolic

Question 5

Fed state and Fast State

Answer 5

We are activating BOTH pathways (anabolic and catabolic pathways)

Question 6

Energy carriers as….

Answer 6

energy currency

Question 7

Macromolecules

Answer 7

Rich sources of energy since much of the energy used to form them is stored within chemical bonds that hold them together

Question 8

The energy released by the oxidation of macromolecules must be?

Answer 8

stored temporarily before it can be channeled into the synthesis of other molecules needed by cells

Question 9

There are two major categories of energy carriers

Answer 9

1. Chemical bond energy
2. Reducing equivalents

Question 10

The energy is stored as high-energy chemical (phosphate) bond

Answer 10

Nucleotides/nucleoside tri-phosphates (NTPs) such as ATP, GTP, CTP, UTP, and dTTP all carry chemical bond energy in the form of high-energy phosphoanhydride bonds

Question 11

ATP is the most _________ energy carrier in the cell, but it cannot be?

Answer 11

Abundant, but it cannot be stored (too unstable). It is produced/used as needed in the cell that produces it.

Question 12

AMP is a signal of?

Answer 12

Low energy in the cell

Question 13

These molecules diffuse within?

Answer 13

Diffuse within the cell and thereby carry their bond energy form sites of energy generation to sites where energy is. Used for cellular activities.

Question 14

The energy is stored in electrons as reducing equivalence

Answer 14

Specialized energy carriers (nucleotide derivatives) accept (oxidized form) and donate (reduced form) electrons. Produced ATP as needed.

Question 15

Water-soluble electron carriers

Answer 15

NAD+ (oxidized, energy poor)
NADH (reduced, energy rich)

NADP+ (oxidized, energy poor)
NADPH (reduced, energy rich)

Question 16

Membrane associated electron carriers

Answer 16

FAD (ETC Complex II)
FADH2 (ETC Complex II)

FMN (ETC Complex I)
FMNH2 (ETC Complex I)

Question 17

Water soluble precursor

Answer 17

Niacin (Vit B3)

Question 18

Membrane associated precursor

Answer 18

Riboflavin (Vit B2)

Question 19

Adding an electron produces an

Answer 19

reduced form of the molecule

Question 20

Why are there two pools of carriers? NAD+ and NADP+

Answer 20

Depending on where you are moving to, you need different means of transportation. Environment dependent.

Question 21

NAD+/NADH signifiance

Answer 21

Catabolic. To accept energy in catabolic reactions. Oxidized form (NAD+) is preferred. (A lot of taxis available to accept passengers once they are ready to go)

Question 22

NADP+/NADPH significance

Answer 22

Anabolic. To donate energy in anabolic reactions. Reduced form (NADPH) is preferred. (We don’t want the body to be waiting to make cells, it needs to be ready right away).

Question 23

Which are preferred?

Answer 23

In Catabolic reactions, Oxidized form (NAD+) is preferred. Anabolic reactions - reduced form (NADPH) is preferred. Water

Question 24

Oxidized to Cystolic ratio & rationale (NAD+)

Answer 24

NAD+: NADH

700: 1

Need NAD+ ready to accept energy from catabolic reactions.

Question 25

Energy is extracted from macromolecules (carbohydrate, protein, or fat) via?

Answer 25

Oxidation of metabolic fuels, resulting in end waste products: CO2 and H2O

Question 26

Oxidized to cystolic ratio & rationale NADP+/NADPH

Answer 26

NADP+/NADPH 1:10 Need NADPH ready to donate energy for anabolic reactions.

Question 27

Proteins in Fed/Absorptive State

Answer 27

from a dietary source dietary proteins of various forms

Question 28

Proteins in Fast/Post absorptive state

Answer 28

from endogenous body reserves endogenous muscle proteins and cellular proteins

Question 29

Carbs fed/absorptive

Answer 29

from dietary source dietary carbohydrates of various forms: mono, di, oligo, polysaccharides

Question 30

Lipids fed/absorptive

Question 31

Carbs fast/post-absorptive

Answer 31

from endogenous body reserves

Question 32

Lipids fast/post-absorptive

Question 33

Proteins are broken into

Question 34

Carbohydrates are broken into

Question 35

Lipids are broken into

Question 36

II: Building blocks (via various pathways) to....

Answer 36

a common intermediate, acetyl CoA

Question 37

There is no dedicated storage for?

Question 38

III. TCA cycle oxidizes what to what? Energy released is what?

Answer 38

NADH, FADH2, and GTP

Question 39

Energy of NADH and FADH2 is released via? Used by? Requires?

Answer 39

Via ETC, and used by ATP synthase to produce ATP. This process requires ATP

Question 40

Insulin/Glucagon goal

Answer 40

to maintain normoglycemia (glucose homeostasis) and to regulate energy metabolism

Question 41

Fed

Answer 41

-0-4 hours after a carbs containing meal -Insulin will be at high levels and glucagon will be at low levels -High insulin/glucagon ratio: helps to lower blood glucose levels

Question 42

Lack of insulin or its "ineffectiveness"

Answer 42

Results in diabetes

Question 43

Short-term fasting

Answer 43

5-24 hours after a meal with carbs Insulin is low Glucagon levels are high Low insulin/glucagon ratio: to maintain a minimal blood glucose levels

Question 44

Long-Term fasting

Question 45

Insulin signaling receptor and effects?

Answer 45

Receptor Tyrosine Kinase (RTK) -Liver, adipose tissue, muscle RTK phosphorylation --> signaling cascade --> increased general phosphatase activities 1. De-phosphorylated state for the selected metabolism-specific enzymes (altered enzyme activity) 2. Gene expression (altered enzyme quantity)

Question 46

Glucagon signaling receptor and effects?

Answer 46

Gs coupled receptor (Ga-s) (Liver, kidney)

Question 47

Epinephrine signaling receptor and effects?

Answer 47

cAMP --> increased PKA activity

Question 48

Liver self-sustaining

Question 49

Cortisol signaling receptor and effects?

Question 50

Fed/Absorptive State Liver (Self Sustaining)

Answer 50

-0-4 hours after a meal -High I/G ratio -Energy generation 1. Liver glycolysis

Question 51

Short Term Fasting: Liver Service to Others

Answer 51

1. Service 1 - Liver glycogenolysis: glycogen to glucose for export 2. Service 2 - Liver gluconeogenesis (slow): non-carb precursors --> glucose for export 3. Service 3 - Ketogenesis (slow): acetyl-CoA (mito) --> ketones for export

Question 52

Long-term liver fast (Self-sustaining)

Answer 52

More than 24 hours post mixed meal. LOWER I/G ratio. 1. Adipose tissue lipolysis: TAG --> FA + glycerol. 2. B-oxidation (FA oxidation): Fatty acids --> acetyl-CoA (mito) 3.

Question 53

Long-Term fasting Liver Service to others

Answer 53

Service 1: NOT glycogenolysis Service 2: MORE/HIGH gluconeogenesis: Non carb precursors --> glucose for export Service 3: Ketogenesis (high): acetyl-coA (mito) --> ketones for export

Question 54

Service Liver Fed/Absorptive state

Answer 54

1. Liver glycogenesis: Glucose-6-P --> glycogen 2. LIpogenesis: TAG synthesis "from scratch" (de novo) in two steps - De novo fatty acid synthesis: Acetyl-CoA (cyto) --> fatty acyl-CoA -TAG synthesis: Fatty acyl-CoA + glycerol-3-P --> TAG

Question 55

Service Liver Short-Term fast/post-absorptive state

Answer 55

-5-24 hours after a mixed meal -Low I/G ratio Adipose tissue lipolysis: TAGs --> fatty acids + glycerol

Question 56

Service Liver long-term fast/post absorptive state

Question 57

Lysis vs. Genesis Table

Answer 57