Lecture 5 Flashcards
Learn necessary concepts for Quiz 2
What are the two main regulating mechanisms of metabolic pathways?
Hormones (insulin, glucagon, epinephrine, corticosteroids), and allosteric enzyme suppression or activation.
What are the compounds that affect the activity of allosteric enzymes?
Modulators
What are the two types of compounds that affect the activity of allosteric enzymes?
Positive modulators (increases activity of enzyme and speeds up rate of reaction) and negative modulators (reduces activity of enzyme and slows down the rate of reaction)
What are the metabolic pathways that are involved in CHO metabolism?
Glycogenesis (creation of glycogen)
Glycogenolysis (breakdown of glycogen)
Glycolysis (oxidation of glucose)
Krebs cycle (oxidation of pyruvate and Acetyl CoA
Gluconeogenesis (making of glucose from non-carbohydrate precursors)
What are the catabolic pathways?
glycolysis, glycogenolysis, proteolysis, lipolysis
What are the anabolic pathways?
gluconeogenesis, glycogenesis, protein synthesis, lipogenesis
1Where is the major site of glycogen synthesis and storage?
liver
What is the other major site of glycogen storage
skeletal muscle
When glucose enters a cell, what is the first product it becomes phosphorylated into?
Glucose-6-phosphate
What enzyme undertakes this function in the liver?
glucokinase
During the synthesis of glycogen, why is it’s branching structure important?
increases the solubility and compactness of glycogen
Which important enzyme in glycogen synthesis is the primary target for insulin
glycogen synthase
Which amino acid regulates the important enzyme in glycogen synthase’s activity?
serine
What is glycogenolysis
break down of glycogen to glucose
what hormones stimulate glycogenolysis?
glucagon and epinephrine
Where in the body is glucagon produced?
pancreas
where is ephinephrine produced?
adrenal medulla
What is the name of the enzyme that converts glycogen to the first breakdown substance in gycogenolysis
glycogen phosphorylase
what is the first substance that glycogen gets broken down into during glycogenolysis?
glucose-1-phosphate
In the last step of glycogenolysis, which enzyme acts on glucose 6 phosphate to produce glucose
glucose-6-phosphatase
Where is the only place that the glucose-6-phosphatase enzyme functions?
the liver.
What enzyme converts glucose to glucose-6-phosphate in the muscles?
Hexokinase
What two forms can glycogen phosphorylase exist in in glycogenolysis?
phosphorylase a (active form) or phosphorylase b (inactive form)
How is the glycogen phosphorylase enzyme regulated?
covalently by adrenaline and glucagon, or allosteric regulation by AMP (increased AMP keeps enzyme inactive)
What is glycolysis?
the oxidation of glucose to either lactate or pyruvate
What is the dominant product of glycolysis under aerobic conditions and what is the next metabolic process it enters into?
pyruvate, which then enters the krebs cycle
what is the dominant product of glycolysis under anaerobic conditions and what is the next metabolic process it enters into?
lactate, cori cycle
How much energy is used and produced during glycolysis?
2 ATP used, 4 ATP, 2 NADH and 2 pyruvate produced. Net 2 ATP, 2 NADH, 2 pyruvate.
What are the 4 stages of glycolysis that Lilli said we need to know?
glucose to glucose-6-phosphate to glyceraldehyde-3-phosphate to pyruvate
How many moles of energy are produced from glycolysis?
6 or 8 depending on whether it occurs in skeletal muscle (6) or liver (8)
Why does glycolysis in skeletal muscle produce less moles of energy than in the liver
because in skeletal muscle tissue, 2 ATP are used to transfer NADH from cytosol to mitochondria
How many moles of ATP are produced in the Krebs cycle?
30
How much ATP is produced in total from glycolysis and the krebs cycle for one mole of glucose to O2 and H2O?
30+6 or 8 = 36 or 38.
Through which two pathways can pyruvate be produced?
Through glycolysis, or gluconeogenesis from amino acids.
What amino acids can be used to produce pyruvate?
Monster Children Toot Amazing Tunes
Methionine, cysteine, tryptophan, alanine, threonine
In glycolysis, what two products can glucose be oxidised into?
lactate and pyruvate
What does the choice of which product is made depend on?
the presence or absence of oxygen
what is the name of the glycolysis cycle that occurs under aerobic conditions
aerobic glycolysis
What is the name of the process by which NADH is generated and used to fuel ATP synthesis?
oxidative phosphorylation (aka kreb’s cycle)
Where does the krebs cycle take place?
mitochondria
What are the coenzymes in glycolysis formed from?
NAD - niacin (B3)
FAD - riboflavin (B2)
What amino acids can acetyl CoA be made from?
ILLT
isoleucine, leucine, lysine, tryptophan
What are the 8 stages of the krebs cycle?
(Can I keep selling sex for money officer?) Citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, succinate, fumarate, malate, oxaloacetate
what are the enzymes involved in the citric acid cycle?
(CAIK Sounds So Freaking Mint)
Citrate synthase, Aconitase, Isocitrate dehydrogenase, alpha-Ketoglutarate dehydrogenase complex, Succinyl CoA synthetase, Succinate dehydrogenase, fumarase, malate dehydrogenase.
What are the amino acids that form alpha-ketoglutarate?
(HOP HAG) hydroxyproline, ornithine, proline, histadine, argnine, glutamate
If the body has sufficient ATP, where might the TCA cycle become blocked?
isocitrate
What amino acids is Succinyl CoA produced from?
VIM: valine, isoleucine, methionine
What amino acids is fumarate made from?
PT: (fumarate) phenylalanine
tyrosine (precursors of dopamine)
What amino acids is oxaloacetate made from?
asparagine, aspartate
What are the cofactors for the conversion of pyruvate to Acetyl-CoA?
TPP (B1), FAD (B2), NAD (B3), CoA (B5), lipoic acid, Mg2+
What enzyme converts pyruvate to Acetyl CoA?
Pyruvate Dehydrogenase Complex
What are the nutritional cofactors necessary for the conversion of lipids to acetyl-CoA?
B1, B2, B3, B5
What are the nutritional cofactors necesary for the conversion of CHO to Acetyl CoA?
B1, B2, B3, B5
What are the nutritional cofactors necesary for the conversion of proteins to acetyl-Coa?
B1, B2, B3, B5, B6
What cofactor is necessary for conversion of citrate to isocitrate?
Fe
What cofactors are needed for conversion of isocitrate to alphaketoglutarate?
B3, Mn, Mg
What cofactors are necessary for the conversion of alpha-ketoglutarate to succinyl-CoA?
B1, B2, B3, B5, lipoic acid
What cofactor is needed for succinyl-CoA to succinate?
Mg
What cofactors are needed for conversion of succinate to fumarate?
Fe, B2
What cofactors are needed for conversion of malate to oxaloacetate?
B3
Which two nutrients carry the hydrogen atoms of rthe electron transport chain?
NADH and FADH2
What are the other 3 nutrients needed in this process?
Sulphur, iron, copper
What are the end products of the ETC?
ATP, water, heat, CO2,
What is the Cori cycle?
pathway that converts lactate from the muscles into glucose in the liver.
What hormone stimulates enzymes to work on glycogen in skeletal muscle cells?
epinephrine
What substance carries lactic acid from muscle to liver?
glutamine
What enzyme in skeletal muscle stimulates breakdown of glycogen?
adenyl cyclase
What does adenyl cyclase stimulate formation of
cAMP from ATP
What enzyme causes phosphorylations in skeletal muscle during glycogenolysis?
protein kinase
What hormone initiates glycogenolysis in skeletal muscle?
epinephrine
Wha tis gluconeogenesis?
synthesis of glucose from non-CHO sources
which process initiates ketogenesis?
starvation
where is gluconeogenesis carried out?
liver and kidneys
from what products can glucose be synthesised from (other than CHO)
amino acids, pyruvate, lactate, lipids
What is ketogenesis?
ketone body synthesis from using fat for energy
