Metabolism Part I

Chapters 13 and 14

Synthesis

Formation of a larger, more complex molecule

Decomposition

Reverse of synthesis, wherein large molecules are broken down to smaller ones

Exchange

Combination of both synthesis and decomposition

Reactants

the matter that begin the reactions (atoms, molecules, etc)

Synthesis

Require energy to break bonds in reactants to form new bonds in products

endothermic reactions

Reactions that trap energy within new molecular bonds

Dehydration synthesis

Water molecule formed (removed)

• anabolic, energy required rxn

anabolism

All the synthesis reactions in an organism are called

Decomposition

Break bonds within larger molecules to form smaller atoms, ions, and molecules

Exothermic

Release energy

hydrolysis

Ionic components of water are added to products

• exothermic rxn

Exchange

•Involve breaking and forming covalent bonds

•Have endothermic and exothermic steps

•Atoms are moved from one molecule to another

Metabolism

sum of the chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material.

Endergonic reactions

require energy

Exergonic reactions

release energy

Redox reactions

Transfer of electrons between two molecules or atoms

electron carriers

NAD⁺/NADH, FAD/FADH₂, and NADP⁺/NADPH are all examples of what?

catabolism

________ in chemoheterotrophs:

• NAD⁺/NADH

• FAD/FADH₂

anabolism

photosynthesis and ________:

• NADP⁺/NADPH

chemical work

refers to synthesis of complex molecules

Transport work

refers to uptake of nutrients, elimination of waste and balance of ions across membranes

Mechanical work

refers to cell motility and movement of structures within or on the surface of a cell

energy

Chemical work, Mechanical work, and Transport work all require what?

ATP (Adenosine triphosphate)

The molecule that stores energy in the cell

high

High or Low?
bonds between phosphate groups are ____-energy phosphate bonds

Exothermic reactions

• form spontaneously

• ΔG°’ is negative

Endothermic reactions

• Form non-spontaneously

• ΔG°’ is positive

Delta G (ΔG°’)

Maximum amount of energy available from the system for useful work under standard conditions

Respiration

The final goal is to generate energy (ATP)

• (aerobic or anaerobic)

ATP

Which molecule:

• has a high phosphate transfer potential

• Readily donates its phosphorylation group to other molecules

higher; spontaneous

The more negative ΔG°’, the _____ (higher/lower) phosphate transfer potential, which means it will be ______ (non-spontaneous/spontaneous).

Oxidation

loss of electrons

Reduction

gain in electrons

Glucose; aerobic

Which rxn is this? Is it aerobic or anaerobic?

C₆H₁₂O₆ + 6 O₂ + 6H₂O → 6 CO₂ + 12 H₂O + energy (ATP)

O2 is reduced to H2O

In this reaction:
C₆H₁₂O₆ + 6 O₂ + 6H₂O → 6 CO₂ + 12 H₂O + energy (ATP)

What is reduced?

C6H12O6 is oxidized to 6CO2

In this reaction:
C₆H₁₂O₆ + 6 O₂ + 6H₂O → 6 CO₂ + 12 H₂O + energy (ATP)

What is oxidized?

Amylase

breaks down glycogen and starch

Cellulase

breaks down cellulose

Glucose

What are these polymers made out of? What will be released?  

• Starch

• Glycogen

• Cellulose

uses

Glycolysis 1^st phase:

uses or generates ATP?

generates

Glycolysis 2^nd phase:

uses or generates ATP?

2; 4; 2

Glycolysis uses ___ ATP, produces ____ ATP and ___ NADH

Glycolysis

Produces energy and reduces electron carries and precursor molecules for metabolism

• most common catabolism of glucose for bacteria, archaea and eukaryotes

• Does NOT require oxygen

substrate level

ATP in glycolysis is synthesized in by which type of phosphorylation?

Pentose-phosphate pathway

• gives it precursors for / important pathway for synthesis of:

  • nucleic acids, amino acids

NADPH

The Pentose-phosphate pathway produces 2 _____.

NADP+; NADPH/H+

Glycolysis and Pentose-phosphate pathway (PPP) share which two electron carriers?

nucleic acids; amino acids

Ribulose 5-phosphate is a precursor (helps create) for what?

pyruvate; Acetyl-CoA

After glycolysis, ________ is decarboxylated and converted into _________.

Eukaryote

Generates pyruvate and converts it into acetyl-CoA in the mitochondria

prokaryote

Generates pyruvate and converts it into acetyl-CoA in the cytoplasm

CO2; NADH

Pyruvate → Acetyl-CoA + ____ + ____

Krebs Cycle (Citric Acid Cycle) (tricarboxylic acid cycle (TCA))

Produces one ATP (or GTP), one FADH2, and three NADH

• recall: they’re all electron carriers

TCA

Intermediates of ____ can be used for biosynthesis of amino acids, lipids, nucleotides etc.

ATP

glycolysis and Krebs cycle are mostly used to generate

catabolic; anabolic

Glycolysis and Krebs cycle are mainly ________, but also support ________ pathways.

anabolic; macromolecules

Glycolysis and the Krebs cycle provide intermediates for ________ pathways to produce ________.

substrate level phosphorylation

a phosphate group is removed from an organic molecule to ADP to make ATP

• only 5 molecules are produced (4 by glycolysis and one by Krebs cycle)

oxidative phosphorylation

occurs through cellular respiration and the most ATP is generated

• ~28 molecules

Krebs cycle

Which cycle?

Glycolysis

Which cycle?