Metabolism Flashcards
Two pathways pyruvate can take
Acetyl CoA –> CAC
Gluconeogensis to G6P, but must cross into mitochondria first, to get converted into OAA –> malate –> shuttle to PEP b/c you can’t convert Pyruvate to PEP directly.
Net products of glycolysis
Which part of glycolysis in NADH made?
2 NADH and 2 ATP
NADH from the energy output portion
How fructose and galactose enter glycolysis
As an intermediate of the 6-C phase
When PPP meets glycolysis - intersection and how they’re related
G3P, Pyruvate doesn’t feed to PPP.
Intermediates from glycolysis like G3P, and F6P can become 4,5,7 C sugars, then become Ribose-5-P by transaldolase and transketolases.
Products created from PPP in oxidative and non-oxidative branches
oxidative - oxidize to reduce NAD+ to NADH
non-oxidative - ribose sugar like for nucleotides
Function of NADPH
cholesterol, FA
antioxidant formation (glutathione)
Bleach in WBC
In what types of tissues does PPP occur most frequently?
Give two examples
tissues that make lipids like liver and adipocytes
How PPP is regulated?
NADPH inhibiting the first step (negative feedback)
Irreversible
Glycogen linkage and branching linkage
Cost of glycogen synthesis
Cost of glycogenolysis
1,4-alpha linkage with branches at 1,6
Glycogen synthesis: one UTP, about one ATP
Glycogenolysis: ATP but instead Pi is enzymatically added to each alpha-1,4 bound glucose
Are the steps with large Gibbs energy difference in glycolysis and glycogenesis reversible? What are the usually accompanied by?
irreversible steps and accompanied by ATP or NADH
Requirement to be a substrate for gluconeogensis
Can lactic acid be a substrate for gluconeogensis
Can fatty acids work? Why or why not?
3-C
YUP
not fatty acids - cleaved 2C at a time
but glycerol can - 3C
how insulin and glucagon control the synthesis, storage, and release of glucose
insulin: decrease blood glucose level in the blood; anything that doesn’t create glucose as the final product like glycolysis and glycogenesis
glucagon: increase blood glucose level in the blood; any metabolic pathway that makes glucose as final product like gluconeogensis and glycogenolysis
Where do all the glucose pathways intersect at?
glucose-6-phosphate
Relationship between G6P and PPP
one way to PPP
beta-oxidation:
Main product
Number of carbons oxidized per oxidation and the byproducts
how fatty acids are broken down into acetly-coA to be released into the mitochondria
2 carbons are oxidized at a time, producing FADH2 and NADH
Products of ketogenesis
Where it occurs
When it occurs
Purpose of ketogenesis
To produce ketone bodies in the mitochondria
Occurs during extreme starvation - when there is an excess Acetyl-coA from too much beta-oxidation of fatty acids that cannot all go into CAC while there is low insulin to convert them back to fatty acids
To route the glucose to brain and blood and supply another form of energy to other organs
T/F all cells in the body can use ketone bodies for energy
False - RBC cannot use ketone bodies for energy
can ketone bodies be substrates for gluconeogensis
no - not 3C
What happens when there is excess acetyl-coA and absence of insulin
what happens when there is insulin?
Ketone body production
insulin - converts excess Acetyl coA into fatty acids
Metabolic pathways that happen few hours after you eat
to increase blood glucose
beta-oxidation, gluconeogensis, glycogenolysis, and ketongenesis in case of extreme starvation
special type of lipoprotein produced by the intestinal cells
pick up to destination; what liver does upon arrival
chylomicrons
intestine to liver; chylomicrons are repackaged in the liver to VLDL or HDL
VLDL vs HDL
VLDL - transport lipids from the liver to other parts of the body
HDL - picks up stray fatty acids and triglycerides from the periphery and brings them to the liver
hormonal vs. intestinal lipase
intestinal lipase: get fatty acids into the cell
hormonal lipase: get fatty acids out of the cell, hydrolyze triglycerides and release free fatty acids into the bloodstream which then undergo beta-oxidation
protein anabolism (protein formation) is associated with what metabolic pathways?
glycolysis, glcogenesis, and lipid storage
protein catabolism is associated with what metabolic pathways?
glconeogenesis, glcogenolsis, beta-oxidation, and ketone body synthesis
what happens to the carbon chain once the nitrogen is removed from the protein?
fed as a substrate for various stages of the CAC
glucose supply immediately after a meal
from intestines
use glucose and store excess glucose as glycogen and triglycerides
Glucose supply few hours after a meal
How is this type of glucose supply compare as the ones coming directly from the intestines during and immediately after a meal?
liver - glycogenolysis, gluconeogenesis
nowhere near as abundant
can glucose cross blood-brain-barrier?
yes
RBC dependence on glucose
Does RBC have mitochondria? What metabolic pathway would it depend on?
depends entirely and only on glucose
has no mitochondria so it relies on fermentation in the cytosol
insulin effect on liver, muscle, adipocytes, and tissues
promotion of glycolysis in all tissues
glycogenesis in liver and muscle
fatty acid synthesis in the liver and fatt acid storage in the adipocytes
glucagon effect on liver, muscle, adipocytes, and all tissues
liver: gluconeogensis, glycogenolysis
beta-oxidation in almost all tissues
fatty acid release in adipocytes
muscle: glycogenolysis
effect of epinephrine and cortisol
Types of stress
How they differ in increasing blood glucose
epinephrine: short-term stress response; glycogenolysis
cortisol: long-term stress; gluconeogensis
what is the polarity of insulin, epinephrine, and glucagon
Thus, where is the receptor?
what about cortisol?
polar, hydrophilic
have receptors on the outside of the cell
cortisol is hydrophobic so it has receptors in the nucleus
hydrolysis of phosphoanhydride bonds (in ATP)
Enthalpy?
Spontaneous?
spontaneous and exothermic; negative gibbs free energy
can provide the energy required for less energetically favorable reactions
products of CAC one turn
3 NADH, 1 ATP, 1 FADH2
one glucose produces how many turns of CAC
2
What regulates CAC?
What happens when NADH builds up?
the amount of NAD+ available
NAD+ is generated by the oxidation of NADH by the ETC. no regeneration of NAD+ - no CAC; CAC is closely linked to ETC so it is aerobic
if NADH builds up, CAC slows down
Once amino acids are deaminated in the liver, to what products can they be converted to and which metabolic pathway can it enter?
can be converted to pyruvic acid or acetyl-coA or it may enter the CAC at various stages
What do fats must convert to in order to enter CAC?
acetyl coA
ATP produced per NADH
2-3 ATP depending on whether or not ATP was spent to bring the NADH into the mitochondrial matrix
ATP produced per FADH2
2 ATP
Another function of cytochrome C
apoptosis in the event of cellular damage
What happens if there is an excess NADH
CAC slows down
Shift the cell into anaerobic fermentation so that NADH can be converted to NAD+ by the conversion of pyruvate to lactate
What are products of fermentation?
lactic acid or ethanoic acid
net ATP of aerobic respiration
36 ATP
NADH produced in acetyl-coA synthesis just before CAC
Where does this happen?
2
inside the mitochondria
ATP, NADH, and FADH2 produced in CAC
1 ATP, 3 NADH, 1 FADH2 per cycle
Where can acetyl coA go?
What can it become?
enter CAC to become citrate or enter glycolysis as an intermediate.
or become glycerol –> gluconeogensis possible
Can brain use ketone bodies?
Can liver use ketone bodies?
To what can ketone bodies be converted to in order to be used as energy?
Brain yes
Liver no
Acetyl-coA
What is beta-oxidation? Where does it take place?
chemical breakdown of fatty acids
mitochondria of liver cells
How does NADH store energy?
in the high energy electrons of its hydrides
What is the Gibbs free energy of hydrolysis of ATP?
negative Gibbs energy, spontaneous
Permeability of mitochondrial membrane
Outer membrane, going into the intermemebrane space: permeable;
Inner membrane: everything except NADH can go in via facilitated diffusion. NADH requires 1 ATP to enter the inner membrane.
What happens when there is no oxygen?
NADH can’t get recycled back to NAD+, CAC shuts down, so the cell has to resort to recycling NADH to NAD+ through fermentation
Acetyl coA - how many C’s
2
