Online quizzes Flashcards
is metabolism the sum total of catabolism and anabolism?
yes
Is the energy produced from catabolism captured as ATP?
yes
Does metabolism refer to the sum total chemical reactions that lead to breakdown or synthesis or biomolecules?
yes
What is an amphibolic pathway?
it can function both catabolically and anabolically
If delta G is negative, does the reaction favour the forward or reverse reaction?
Forward
How much ATP do we consume daily?
80kg
Which carrier is an activated carrier of electrons used in biosynthetic reactions?
NADPH
Many activated carriers are
derived from B vitamins
Why is too much fructose bad?
metabolized in a way that it passes the main regulatory point in glycolysis, leads to excess flow and too much fat
What is net ATP thru glycolysis?
2
Converting pyruvate to what produces the most energy>
Acetyl CoA
Galactose produced from lactose degradation can be metabolized to what?
Glucose 6p
What is the main regulatory enzyme of glycolysis?
PFK
What is an allosteric activator of PFK in liver?
Fructose 2,6 bisp
what is the final enzyme in gluconeogenesis?
glucose 6 phosphatase
What are three precursors for gluconeogenesis?
pyruvate, glycerol and lactate
What type of reaction does fructose 1 6 bisphosphatase catalyze?
Hydrolysis reaction
How many glycerol molecules are needed to make 1 glucose?
2
What bodily condition would cause gluconeogenesis to be active in the liver?
Sleep
When does the cori cycle occur?
When oxygen in muscle is limiting
The PPP is linked to glycolysis through what molecule?
glyceraldehyde 3p
What is oxidized in the oxidative phase of PPP?
glucose 6p
Why is PPP important?
Provides 5 carbon sugar for nucleotide synthesis
What do transketolase and transaldolase do?
help cell deal with imbalance in need for reducing equivalent and ribose 5p
- some products are glycolytic intermediates
Where can free glucose go when it enters the cell?
glycolysis or PPP
The regulation of PPP…
involves stimulation by high levels of NADP+, occurs by an allosteric mechanism
How many ribulose 5p molecules are produced per NADPH in PPP?
0.5
Where in the cell is the PPP?
cytosol
What part of glycogen means it can be quickly synthesized or degraded?
branched structure
How frequently do 1-6 linkages occur?
10 residues apart
What enzyme changes glucose 6p to glucose 1p
phosphoglucomutase
What are the products of the reaction catalyzed by glycogen phosphorylase?
glucose 1p and glycogen that is one molecule shorter
debranching enzyme…
differs from glycogen phosphorylase in that it releases free glucose
Glycogen synthase and glycogen phosphorylase share what property?
both are activated by camp
_____ is one of the products of the reaction catalyzed by the PDH, it can enter the _____
Acetyl CoA, it can enter the citric acid cycle
What does the Warburg effect refer to?
the feature of tumors to metabolize glucose into lactate instead of pyruvate even in the presence of oxygen
The high energy electrons that are generated in the citric acid cycle are initially captured in the form of _____
NADH and FADH2
How many CO2 molecules are released during one round of the citric acid cycle?
2
The substrates for the first reaction in the citric acid cycle are?
acetyl CoA and oxaloacetate
Why is regulation of the citric acid cycle necessary?
because the acetyl CoA that enters the cycle is derived from multiple pathways
in addition to capturing high energy electrons through the oxidation of acetyl coa, another important function of the citric acid cycle is:
to provide intermediates for the synthesis of other biomolecules
The two products of the electron transport chain are:
H2O and ATP
What cellular compartment are the ETC complexes located?
inner mitochondrial membrane
What is the final electron acceptor in the ETC?
O2
What is the issue with reactive oxygen species?
they are highly reactive within many biomolecules in the cell
triacylglycerol degradation in adipose tissues releases ____
fatty acids
Which biomolecule facilitates the transport of fatty acids into the mitochondrial matrix?
Carnitine
Every round of beta oxidation releases ____ _____ molecules except the last one which releases ____
one acetyl coa, two
There is no ____ directly generated in beta oxidation?
ATP
Does beta oxidation involve a dehydration step?
no
The oxidation of odd chain fatty acids produces ____
propionyl CoA which is converted to an intermediate of the citric acdi cycle
Ketone bodies are synthesized in what part of what organ?
mitochondria of the liver
The oxidation of fatty acids generates more energy than glucose because:
They are more reduced than glucose and thus generate more high energy electrons
Fatty acids cannot be used to supply carbons for ____
glucose syntehsis
How does acetyl coa get form the mitochondria to the cytosol so it can be used in fatty acid synthesis?
it is converted to citrate which can be transported out to the cytosol where it is broken down to oxaloacetate and acetyl coa
What does Acyl carrier protein (ACP) do?
acts ass an arm which moves the intermediates of fatty acid synthesis from one enzyme to the next.
NADP required for fatty acid synthesis comes from where?
The process of transporting acetyl coa to the cytosol
What is required to produce a 19 carbon unsaturated fatty acid?
you must start fatty acid synthesis with propionic acid
What is the key regulatory enzyme in fatty acid synthesis?
acetyl coa carboxylase
What are three required ingredients for synthesizing palmitate?
ATP, NADPH, Acetyl CoA
What do phospholipids and triacylglycerols have in common?
they both have a glycerol backbone
Fatty acids are linked to glycerol through what kind of bond?
ester bonds
CDP-diacylglycerol is a precursor for what two products?
phosphatidylcholine and phosphatidylserine
What molecule is the building block for cholesterol synthesis?
Acetyl CoA
What is the main regulatory enzyme in cholesterol synthesis?
HMG CoA reductase
Which biomolecule provides the reducing power needed for cholesterol synthesis?
NADPH
How do statins lower plasma cholesterol levels?
they inhibit the cholesterol synthetic pathway
What is the primary role of LDLs?
To deliver cholesterol to tissues
The transamination reaction funnels amino groups into what biomolecule?
glutamate
What is the aketoacid product of alanine transamination?
Pyruvate
What product of the glutamate dehydrogenase reaction is used for urea synthesis?
NH4+
The ammonia that is produced by the spleen is transported to the liver as ____
glutamine
Urea is released by the hydrolysis of what molecule?
Arginine
Which amino acid is used to deliver ammonium from non muscle tissues to the liver?
Glutamine
In the synthesis of a urea molecule, one of the amino groups comes from free ammonium, the other one comes from?
aspartate
Which vitamin is a cofactor for aminotransferase reactions?
Vitamin B6 - pyridoxal phosphate
Which two amino acids is ammonia initially assimilated into by plants?
glutamate and glutamine
Which enzyme serves as the main regulatory point in nitrogen metabolism>
glutamine synthetase
S-Adenosylmethionine provides what group during the synthesis of other biomoleculews?
Methyl groups
Amino acids can be synthesized from intermediates of what three pathways?
Glycolysis, citric acid cycle, PPP
Oxaloacetate is the direct precursor for which amino acid?
Aspartate
Which enzyme in serine biosynthesis is allosterically controlled?
3-phosphoglycerate dehydrogenase
Besides glutamine, which other amino acid is a source of amino groups?
glutamate
what two biomolecules provide the one carbon units that THF carries?
Serine and formate
The major products of nucleic acid digestion in the small intestine are?
nucleosides
What is the major end product of purine degredation?
Uric acid
What biomolecule provides 4/6 atoms in pyrimidine rings?
aspartate
RNR is involved in what process?
synthesizing deoxy shit
What is the product of thymidylate synthase?
dTMP
5-fluorouracil inhibits which enzyme?
thymidylate synthase
What is the major enzyme involved in salvaging purines?
hypoxanthine-guanine phosphoribosyltransferase
Which organ acts as a glucose sensor?
liver
What is the fate of glycerol that is produced in adipose tissue when triacylglycerol is degraded?
it is released into the blood and used in the liver as a substrate for gluconeogenesis
Which organ consumes the most glucose>
brain
Which organ cannot use fatty acids as an energy source>
brain
Which hormone plays the biggest role during starvation?
glucagon
Name one metabolic pathway stimulated by insulin
hepatic fatty acid synthesis
