slide1
Download
Skip this Video
Download Presentation
Review of Basic Metabolic Principles

Loading in 2 Seconds...

play fullscreen
1 / 13

Review of Basic Metabolic Principles - PowerPoint PPT Presentation


  • 89 Views
  • Uploaded on

Review of Basic Metabolic Principles. A. Energy Currency of the Cell. Metabolic pathways can be classified as either: energy generating (catabolic) …or energy utilizing (anabolic). The cell also uses two types of energy currency:. 1. Phosphate anhydrides (compounds with high

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Review of Basic Metabolic Principles' - olathe


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Review of Basic Metabolic Principles

A. Energy Currency of the Cell

  • Metabolic pathways can be classified as either:
    • energy generating (catabolic)…or
    • energy utilizing (anabolic)

The cell also uses two types of energy currency:

  • 1. Phosphate anhydrides(compounds with high
      • phosphate transfer potential)

General: hydrolysis of a phosphate ester

+

+

ATP hydrolysis

ATP

+

+

slide2

Free Energies of hydrolysis of some phosphorylated

    • compounds
  • ATP is the most commonly used compound with
    • high phosphate transfer potential
    • phosphoenolpyruvate & creatine phosphate
      • have enough energy to synthesize ATP
    • ATP can be used to synthesize glucose 6-
      • phosphate & similar compounds
  • GTP is sometimes used in place of ATP
slide3

ATP is called the energy currency of the cell

Catabolism

Anabolism

O2

Work

Heat

ATP

Foods

Biosynthesis

CO2 + H2O

[Energy]

  • Definitions:
    • catabolism is the production of energy from
      • food
    • anabolism is the utilization of energy to provide
      • heat, do work, or drive biosynthetic reactions
  • Reducing equivalents(compounds with high
      • electron transfer potential)

Foods → NADH and FADH2 → ATP for Biosynthesis

  • The reducing equivalents in the foods we eat…
    • are transferred to NADH and FADH2
    • NADH and FADH2 transfer their electrons to
      • the electron transport chain which..
    • uses the energy in those electrons to synthesize
      • ATP
slide4

Based on what you already know, you might predict

    • that:
    • catabolic pathways produce NADH, FADH2, &
      • ATP
    • anabolic pathways utilize ATP, NADH, & FADH2
  • However, that’s not quite true. In reality:
    • catabolic pathways produce NADH, FADH2, &
      • ATP
    • anabolic pathways utilize ATP, NADPH, & FADH2

B. Coenzymes

1. Definition

  • Coenzymes are small molecular weight
    • compounds that are:
    • necessary for the catalytic activity of
        • one or more enzymes
    • present in very small amounts compared
        • to the substrates of the enzyme
    • used over & over in a catalytic manner
  • most coenzymes exist free in solution
  • some coenzymes are bound to proteins
    • = prosthetic groups
slide5

2. Coenzymes carry some biologically important

    • chemical group in an “activated” (high energy)
    • form so that it can be used in biosynthetic
    • reactions

Example = coenzyme A (carries acyl groups)

+ CoASH

+ H20

acetic acid

acetyl CoA

G = -7.5 kcal/mole

+ CoASH

+ H20

acyl CoA

carboxylic acid

slide6

3. Coenzymes are sometimes derived from vitamins

Some activated carriers in metabolism

slide7

C. What Does a Metabolic Pathway Look Like?

  • many reversible reactions
  • a few irreversible reactions that drive the
    • pathway
  • the irreversible reactions are important!

A

B

C

D

E

F

E1

E2

E3

E4

E5

D. Control of Metabolism

1. Controls Which Operate at a Cellular Level

  • regulation is by inhibitors & activators in cell

a. Which metabolites usually regulate pathways?

  • The precursor of a pathway usually
      • stimulates the pathway

+

A

B

C

D

E

  • ii. The end product of a pathway usually
      • inhibits the pathway

-

A

B

C

D

E

slide8

iii. The end product of a competing pathway

      • often stimulates the other pathway

A

B

C

D

E

+

G

H

I

  • Energy utilizing & producing pathways
      • are often regulated on the basis of
      • ATP supply in the cell
    • Catabolic pathways are inhibited by
      • ATP and/or stimulated by ADP or AMP
    • Anabolic pathways are stimulated by
      • ATP and/or inhibited by ADP or AMP

b. Where are pathways regulated?

i. At or near a branch point

D

A

*

B

*

C

slide9

ii. At 1st committed (irreversible) step

*

A

B

C

D

E

2. Controls that operate at whole body level

  • sites of regulation similar, but mechanisms different
  • Peptide hormones (glucagon, epinephrine,
      • & insulin)
  • act via second messenger (eg, cAMP)
  • result in phosphorylation or dephosphoryl-
    • ation
  • alter enzyme activity
  • are fast acting

b. Steroid hormones (cortisol)

  • travel to nucleus & bind to DNA
  • affect amount of enzyme made
  • are slower acting
slide10

Pi

O

+

OPi

E. Glossary of Enzyme Names

  • Kinase: catalyzes the phosphorylation of some
    • metabolite, usually with ATP as the donor

Example = glucokinase or hexokinase

ATP + glucose → ADP + glucose 6-phosphate

  • Phosphatase: catalyzes the hydrolytic removal
    • of a phosphate group (also called
    • dephosphorylation)

Example = glucose 6-phosphatase

glucose 6-phosphate + H2O → glucose + Pi

  • Phosphorylase: catalyzes the phosphorolytic
    • cleavage of a bond (phosphate is the
    • attacking nucleophile)

Example = glycogen phosphorylase

slide11

Hydrolase: catalyzes the hydrolytic cleavage of

    • some bond (water is the attacking nucleophile)
  • Often subclassified according to bond cleaved
    • Esterase: hydrolyzes ester bond
    • Peptidase: hydrolyzes peptide bond
    • Phospholipase: hydrolyses phospholipids
  • Dehydrogenase: catalyses oxidation-reduction
    • reactions by the transfer of hydrogens
    • (electrons). Generally use NAD+/NADH or
    • FAD/FADH2.

Example = lactate dehydrogenase

  • Synthetase or synthase: catalyzes the joining of
    • two molecules to create a larger molecule

Example: citrate synthase

oxaloacetate + acetylCoA + H2O → citrate + CoASH

(4 carbons) (2 carbons) (6 carbons)

slide12

Carboxylase: catalyzes the addition of CO2 to a

    • molecule. Uses biotin as a coenzyme

Example = pyruvate carboxylase

OAA + ADP + Pi

pyruvate + CO2 + ATP + H2O

  • Transferase: catalyzes the transfer of a group from
    • one molecule to another. Subclassified
    • according to group transferred
  • Transaminase: transfers amino groups. Uses
    • pyridoxal phosphate as a coenzyme.

Example = aspartate transaminase (AST)

+

+

-ketoglutarate

Aspartate

Glutamate

Oxaloacetate

slide13

Transaldolase: transfers aldehyde groups. Uses

    • thiaminepyrophosphate as a coenzyme

aldehyde:

  • Transketolase: transfers ketone groups. Uses
    • thiaminepyrophosphate as a coenzyme

ketone:

  • Acyltransferase: transfers acyl (carboxylic acid)
    • groups. Uses coenzyme A as a coenzyme

acyl (carboxylic acid):

Methyltransferase: transfers methyl groups.

Decarboxylase: removes carboxyl groups as CO2

Isomerase: converts from one isomer to another

ad