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the first stage of energy extraction for carbohydrates
glycolysis
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define glycolysis
the oxidation of glucose to form pyruvate, ATP, and NADH
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fates of glucose in higher animal and plant cells (3)
- 1) glycogen (storage as starch & sucrose)
- 2) pyruvate (oxidation via glycolysis)
- 3) ribose 5-phosphate (oxidation via pentose phosphate pathway)
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3 types of chemical transformation
- 1) degradation & oxidation of glucose carbon skeleton to yield pyruvate
- 2) phosphorylation of ADP to ATP (high energy production)
- 3) transfer of hydride ion (:H-) to NAD to yield NADH
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glycolysis net ATP & NADH
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fates of glucose under anaerobic conditions (2)
- 1) glucose -> 2 pyruvate -> 2 EtOH + 2CO2
- 2) glucose -> 2 pyruvate -> 2 lactate
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what lactose intolerance is due to
disappearance of lactase activity from intestinal epithelial cells -> can't be absorbed/digested, converted into toxic products by bacteria
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name 3 important regulatory enzymes in glycolysis
- 1) hexokinase (glucose -> G6P)
- 2) PFK1 (F6P -> F1,6BP)
- 3) pyruvate kinase (PEP -> pyruvate)
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predominant hexokinase in liver
- glucokinase
- OR
- hexokinase IV
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hexokinase in skeletal muscle
hexokinase I
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why is the affinity for glucose 100x higher in muscle than liver?
muscle needs a constant supply, while liver acts as buffer releasing its glucose only when needed
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The phosphorylation of ADP → ATP has a what type of G?
positive
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what activates PFK-1? (3)
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phosphorylated pyruvate kinase is (more/less) active
LESS ACTIVE
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what inhibits pyruvate kinase? (4)
- 1) ATP
- 2) acetyl-CoA
- 3) alanine
- 4) long-chain FAs
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how pyruvate kinase is inhibited
ATP phosphorylates it, decreasing its affinity for PEP
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what is pyruvate kinase activated by
F1,6BP
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what is the fate of pyruvate during the aerobic phase of catabolism?
oxidized to H2O & CO2 during cellular respiration
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pyruvate provides the ____ for the CAC.
acetyl groups
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The outer membrane is ___________ (permeable or impermeable) whereas
the inner membrane is ___________ (permeable or impermeable).
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What type of reactions replenish the intermediates that are removed from
the citric acid cycle?
anaplerotic reactions
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pathways protein can be run through (2)
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What are the 3 excretory forms of nitrogen?
- 1) ammonia
- 2) urea
- 3) uric acid
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net yield of products from the CAC (PER PYRUVATE MOLECULE)
**per glucose molecule -> 6 NADH, 2 FADH 2
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Where does most of our ATP come from?
A combination of the CAC and oxidative phosphorylation.
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electron transport and oxphos occur in ____.
mitochondria
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The oxidation of ___________ is associated with NADH production which provides a
source of electrons for ___________ and ___________.
- FAs
- electron transport
- oxphos
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what makes the outer mitochondrial membrane permeable?
porins
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importance of impermeable inner mitochondrial membrane
allows for the establishment of steep chemical gradients
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concentration of H+ is ___ in the inter-membrane space.
high
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concentration of H+ is ___ in the mitochondrial matrix.
low
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the electrons stripped from each NADH drives the synthesis of ___ ATP.
2.5
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the electrons stripped from FADH2 generate ___ ATP.
1.5
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2 things that drive ATP synthesis in conjunction with ATP synthase
- 1) pH gradient
- 2) transmembrane potential
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complex in ATP synthase that catalyzes ATP synthesis
F1
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complex in ATP synthase that acts as the proton pore
F0
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What is the total ATP output after the complete oxidation of Glucose?
30 or 32
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How would treating someone with cyanide poisoning by converting Hb to met-Hb help
them not die a horrible death?
The CN- would react with the Fe3+ of met-Hb instead of reacting with the Fe3+ in the heme of cytochrome oxidase complex (which would inhibit electron transfer)
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Initially, what condition do most tumors grow in?
anaerobic
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What metabolic pathway/process increases 10-fold in regions occupied by tumors?
glycolysis
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