metabolism

metabolic pathways

Consecutive enzymatic reactions that converge on intermediates.

anabolic vs catabolic

Synthesis (builds molecules; requires energy) gluconeogenesis

Degradation (breaks molecules; releases energy) glycolysis

energy source

ATP and NADH

metabolism

all chemical reactions for cell growth/ division

glycolysis

reactions that breakdown complex to simple compounds and make energy

gluconeogenesis

reactions make complex from simple compounds and use energy

principle characteristics of metabolic pathways

irreversible

catabolic/ anabolic pathways differ

every path has committed 1st step

have rate-limiting step

occur in locations/ organs

catabolism steps

Proteins → Amino Acids

Polysaccharides → Glucose (Monosaccharides)

Triacylglycerols → Fatty Acids + Glycerol

degraded into 2-carbon intermediate:

Glycolysis: Glucose breaks into Pyruvate, makes ATP / NADH

Pyruvate/Fatty Acids/Amino Acids change to Acetyl-CoA.

CO2​ is released; NH3​ is removed from amino acids.

in mitochondria

Citric Acid Cycle (Krebs): Acetyl-CoA oxidizes electrons to carriers (NADH and FADH2​) CO2 releases

Oxidative Phosphorylation: The electrons from NADH and FADH2​ are used in the electron transport chain. oxygen goes in, ATP and water come out

types of reactions

catalyzed by enzyme

• group-transfer reactions

• oxidation and reductions

• eliminations, isomerizations, and rearrangements

• reactions that make or break carbon-carbon bonds

redox vs oxidation reactions

gain electrons

lose electrons

glycolysis

10 enzyme catalyzed reactions

B-D-glucose becomes Pyruvate

yields 2 atp/ nadh

phase 1 and 2 of glycolysis

consume 2 atp, split 6 carbon glucose in 2,3 carbon compounds

make 2 atp, 1 nadh by dephosphorylation of 3 carbon compounds

glycolytic enzymes types

kinases

isomerases/ mutases

specialized k

kinases

transfer phosphoryl groups from donors to acceptors

isomerases/ mutases

catalyze internal rearrangements

specialized enzymes

aldolase splits 6-carbon sugar → two 3-carbon sugars

dehydrogenase makes NADH

enolase makes PEP

hexokinase

phosphoryl group transfer from ATP to the O6 of glucose

conformational change when bound to substrate

excludes water

Glucose-6-Phosphate Isomerase

Reversible isomerization of G6P to F6P

prepares 6 carbon sugar foral phosphorylation

Aldoase

cleave 6C sugar → 3C sugar pair

Triose Phosphate Isomerase

fast eversible isomerization of DHAP to G3P

GAPDH dehydrogenase

G3P/Pi/ NAD+ → BPG/ NADH/ H+

C1 is oxidized, NAD+ reduces to NADH

Phosphoglycerate Kinase

1st substrate level phosphorylation

BPG → ADP make ATP

2 lobes swing together when bound

enolase

dehydrate 2-PG to make PEP

pentose phosphate pathway

makes NADPH and D-ribose in degradation for ATP energy