Test 3 questions and answers Flashcards
The main site for gluconeogenesis is:
A. liver
B. muscle
C. kidney
D. brain
A. liver
The glycosidic bond:
A. in maltose is not hydrolyzed in lactose intolerant humans
B. in sucrose is hydrolyzed by bees
C. joins glucose and fructose to form sucrose
D. both (B) and (C)
D. both B and C are correct
Glycogen degradation requires the enzymes namely:
A. glycogen synthase and phosphorylase
B. glycogen phosphorylase and glycogen-debranching enzyme
C. glycogen dehydrogenase and glycogen-debranching enzyme
D. glycogen kinase and glycogen splitting enzyme
B. glycogen phosphorylase and glycogen-debranching enzyme
Two major products of the pentose phosphate pathway are:
A. NADPH and NAD
B. FAD and CoA
C. flavine adenine dinucleotide and glucose 5-phosphate
D. nicotinamide adenine dinucleotide and ribose 5-phosphate
D. nicotinamide adenine dinucleotide and ribose 5-phosphate
A catabolic intermediate which stimulates phosphofructokinase would stimulate:
A. glycogen synthesis
B. glycolysis
C. gluconeogenesis
D. glycogenolysis
B. glycolysis
A fatty acid with 14 carbon atoms will undergo how many cycles of beta oxidation?
A. 14
B. 7
C. 6
D. 1
C. 6 cycles
Which of the following is the primary ketone body?
A. Acetone
B. Acetoacetate
C. Beta-hydroxy buterate
D. Hydroxy Methyl glutarate
B. acetoacetate
Choose the INCORRECT statement about cholesterol synthesis:
A. All the carbon atoms are derived from Acetyl-CoA
B. Process is cytoplasmic
C. NADPH is the main coenzyme
D. Highly expensive energetically
B. process is cytoplasmic
Lipolysis of triacylglycerols is stimulated by:
A. insulin
B. glucagon
C. ATP
D. dopamine
B. glucagon
Which lipoprotein has the highest content of protein?
A. VLDL
B. LDL
C. HDL
D. Chylomicrons
C. HDL
Which lipoprotein has lowest content of protein
Chylomicrons
Which fatty acid is this?
Stearic acid
Which apolipoproteins transport dietary triglycerides from intestines
Chylomicrons
Hormones stimulating lipolysis
Epinephrin
How are fatty acids transported in the bloodstream
Bound to albumin
Number of beta-oxidation cycles needed to oxidise a fatty acid (no, of carbons 12) - 1
Depends on the length of the fatty acid and chain, for 12 its 5
How many ATP molecules are required for activation of fatty acids?
2 ATP
Important enzyme in ketogenesis
HMG CoA synthase
How does dietary glucose enter cytoplasm of enterocytes
By symport
What phospho sugar is this?
Glucose-1-phosphate
What is predominant glucose transporter present on surface of erythrocytes
Glut 1
Glut 2 happens where?
In the liver
Glut 3 happens where?
In the kidneys
Alpha - 1,4 bonds are hydrolyzed by enzyme called..
Amylase
An enzyme phosphoglucomutase transforms
Glucose - phosphate to glucose-6-phosphate
Hormones promoting glucagon dehydration
- Glucagon
- Epinephrine
Hormones involved in gluconeogenesis
- Glucagon
- Norepinephrine
- Epinephrine
- Cortisol
- Thyroid + growth hormones
Choose activated sugar which a substrate of glycogen synthase
UPD glucose
Animals which have increased contents of fast twitch myocyte fibres
- Rabbit
- Cat
Net energy profit from degradation of one glucose molecule through glycolysis is
- 2 ATP
- 2 NADH
Propianate CoA generated after beta oxidation of odd number fatty acids is transformed into..
Succinyl CoA
Organs that metabolise ketone bodies
- Brain
- Heart
- Skeletal muscle
What is source of two carbon units for fatty acid synthesis
- Acetyl CoA
Fatty acid synthase of mammals contains
- 7 enzymatic activities and ACP
Common precursor of triglyceride + glycerophospholipid synthesis is
- Phosphatic acid
Compound having a major role in regulation of fatty acid synthesis + breakdown
- Molony CoA
Glycosidic bonds present in glycogen
- A-1,4
- A-1,6
Which organ expresses an enzyme glucose-6-phosphate (gluconeogenesis)
- Liver
Products of glucogen hydrolysis
- Glucose
Name of protein in center of glucagon
- Glucogenin
Hormones stimulating lipolysis
- Cortisol
- Glucagon
- epinephrine
- Norepinephrine
- Growth hormone
How are free fatty acids transported in bloodstream
- Bound to albumin
How are steroid hormones transported in blood
- bound to globulins
Enzymes operating during b-oxidation of fatty acids
- Acyt CoA dehydrogenase
- Thiolase
- Enoyl CoA hydratase
How many b-oxidation cycles are necessary to completely degrade one molecule of stearate
- 8
2 enzymes requiring the same cofactor + using is the same catalytic mechanism
- pyruvate dehydrogenase
- Alpha-ketoglutarate dehydrogenase
Product of fumerase enzyme
- Maleate
How many high energy electrons are produced from the oxidation of one acetyl CoA in krebs cycle
- 8
Which apolipoproteins transport dietary triglycerols from intestine
- Chylmirons
Enzyme playing major role in controlling rate of glycolysis
- Phosphofructo kinase
Irreversible glycolysis reaction
- Glucose –> glucose-6-phospate
Products of the oxidative phase of pentose phosphate pathway
- nucleotide sugars
- NADPH
What enzyme mediates this reaction
- Lactate dehydrogenase
Metabolites of non-oxidative phase of pentose pathway that have direct link with glycolysis
- Fructose-6-phosphate
- 3 phosphoglyceraldehyde
In the process of glycolysis, 1 glucose molecule converts to..
2 pyruvate molecules
Compounds that inhibit activity of phosphofructo kinase
- Citrate
- ATP
Metabolic target of oxidative phase of pentose phosphate pathway
- NAD+ reduction
- Synthesis of nucleotide precursors
Enzyme of non-oxidative phase of the pentose pathway transferring two-carbon fragments of sugar is
- Transketolase
The presence of pyridoxal phosphate (PLP) is necessary for what reaction
- Conversion of glucose-1-phosphate to glucose-6-phosphate
In corich cyde, working muscles secrete in blood..
- Lactate
Steps in glycolysis that lead to breakdown glucose in order
- Conversion of glucose-6-phosphate to fructose-6-phosphate
- Cleavage of fructose-1,6-biphosphate to 2 phospho trioses
- Formation of 1,3-biphosphoglycerate
- converting 3 phosphoglycerate to 2 phosphoglycerate
- formation of phosphoenollpyruvate
What is cellulose
- Glucose homopolymer
What process is the source of the main substrate of the krebs cycle containing 3 carbon
- Glycolysis
Compounds that are activators of dehydrogenase
- ADP
- ATP
Bloodstream of fasted dogs
- Ketone bodies
Primary bile acid
- cholic acids
- chenodeoxycholic acid
Common precursor of steroid hormones formed from cholesterol
Pregnenolone
Which amino acid does not undergo transmination
- proline
- threonine
What cellular compartment is glutamate dehydrogenase present
- mitochondrial matrix
What are products of arginase reaction
- amithine and urea
During beta-oxidation of fatty acids, propionyl-IN-CoA is converted to
- Something CoA which enters citric acid cycle (succinyl)
What enzyme catalyzes more than one reaction during oxidation
- Dehydrogenase
When oxaloacetate is unavailable, acetyl-CoA is converted
- Acetone
- Acetylacetate
- B-hydroxybutrate
The synthesis of C16 fatty acids proceeds
- in the cytosol, with participation of NADPH
Arachidonic acid is not a precursor of..
Cholesterol
Non-steroid anti-inflammatory drugs are broad, heterogeneous group of anti-inflammatory, analgesic and antipyretic drugs, work by inhibiting activity of
- Cycloxygenases
Statin is a drug used to lower blood cholesterol. Works by inhibiting
- 3-HMG-CoA reductases
- mevalonate formation reaction
High density lipoproteins..
- Transport cholesterol from tissue to liver
- Have apoprotein A, E + C in their composition
Progesterone in hormone
- Cholesterol derivatives, responsible for maintaining pregnancy
- Allowing implantation of embryo into uterine mucosa
The presence of pyridoxal phosphate (PLP) is necessary for what reaction
- Glycogen breakdown catalyzed by glycogen phosphorylase
Coric cycle
- Lactate
Which process is source of main substrate of krebs cycle containing 3 carbon atoms
- Glycolysis
Product of glycogen hydrolysis
- Glucose
Irreversible glycolysis reaction
- Phosphoenolpyruvate -> pyruvate
Production from oxidate of PPP
- nucleotide sugars
- NADPH
Glucagon + Epinephrine
- Stimulates gluconeogenesis + inhibits glycolysis
Catabolic intermediate stimulating phosphofructokinase will also stimulate
- Glycolysis
Arachidonic acid is a precursor of
- Prostaglandins
- Leukotrienes
- Prostacyclin
In which cell does the rapapo-lubering shunt operate
- Erythrocytes
In liver, dietary fructose is converted to
Fructose-1-phosphate
Enzyme mediating this reaction
- Pyruvate carboxylase
Products of oxidative phase of pentose phosphate pathway
- NADPH
- Nucleotide sugars
Enzyme controlling rate of pentose phosphate pathway
- Glucose-6-phosphate dehydrogenase
Beta oxidation of fatty acids takes place in
- Mitochondrium
Synthesis of fatty acids takes place in
- Cytoplasm
Krebs cycle takes place in
- Mitochondrium
Biological functions of cholesterol
- Precursor of bile acids
- Precursor of vitamin D
- Precursor of steroid hormones
- Component of lipid rafts
What is the proportion of de novo cholesterol synthesis relation to dietary cholesterol uptake
- 85%
Lipoprotein that has the highest cholesterol contents
- LDL
Lipids in the bilayer
- Inner
–> Phosphatidylserine
–> Linositol
–> Lethanolamine - Outer
–> Phosphatidylcholine
–> Glycolipids
–> Glycoproteins - Both
–> Cholesterol
Key enzyme that allows the use of ketone bodies as an energy source in extracellular tissues
- CoA transferase
What is the source of Acetyl-CoA needed for synthesis of fatty acids in cytoplasm
- Citrate
What is function of APO-11
- Activates lipoprotein lipase
Factors that promote cholesterol synthesis in liver
- Insulin
- Low concentration of non-steroidal mevalonate metabolism
HMG-CoA synthase is involved in synthesis of
- Cholesterol
- Ketone bodies
Name of aminotransferase that performs following RXN
- Aspartate aminotransferase
Correct type of LDL update mechanism
- Receptor-mediated endocytosis
Consequences of LDL receptor deficiency
- increased plasma cholesterol levels
- Increased probability of coronary heart disease
- Common xanthomas
Organs in which cholesterol synthesis occurs
- Liver
- Ovaries
- Adrenal cortex
Enzyme targeted by statins
- HMG-CoA reductase
Correct rotation for squalene synthase reaction
- CIS + CIS –> C30
Factors inhibiting HMG-CoA reductase
- Fasting
- Cholesterol intake
- Phosphorylation
Primary bile acids
- Cholic acid
- Chenodeoxycholic acid
Mineralocorticoid
- Aldosterone
Calcitriol (activate form of vit D) is generated from vitamin D3 by following modifications
- Successive hydroxylations
Steroid + peptide hormones are equally well cell permeable
- false
Peptide hormones more diverse than steroid
- true
Steroid hormones are same from species to species
- true
Steroid hormones can be stored in place of synthesis
- false
Peptide hormones are always bound to carrier protein
- false
Glycolysis stage 1
- 2 ATP invested
- Glucose is phosphorylated
- Converted to fructose
- Cleaved into 2 molecules = glyceraldehyde + 3 Phosphate
Glycolysis stage 2
- Glyceraldehyde 3 phosphate converted to pyruvate
- Generates 4 ATP + 2 NADH = only 2 ATP used
How is glycolysis regulated
- substrate + enzyme is limited
Enzymes regulated in glycolysis
- Hexokinase
- Phosphofructo kinase
- Pyruvate kinase
ATP in glycolysis + gluconeogenesis
- 2 ATP made in glycolysis
- 4 ATP used in gluconeogenesis
How does fructose 2,6-biphosphate regulate glycolysis + gluconeogenesis
- Activates phosphofructokinase-1
- Activates transcription of hexokinase
- Inhibits fructose 1,6-biphosphate
3 fates of glucose 6-phosphate
- glycolysis
- glycogenolysis
- pentose phosphate pathway
Enzyme for glycogenesis
- glycogen synthase
Enzyme for reverse of glycogenesis
- UDP glucose pyrophospyrase
How is glycogen synthase regulated
- Phosphorylation leads to inactivation
Regulation of pentose phosphate pathway
- first step irreversible
- NADPH is inhibitor of glucose 6-phosphate dehydrogenase
- Induced by insulin
How many ATP molecules required for activation of fatty acids
2 ATP
Location of ketogenesis
- mitochondria
Enzyme in ketogenesis
- HMG CoA synthase
Final product of lipogenesis
- palmitic acid C16
What activates lipogenesis
- Insulin
- High blood glucose
Coenzymes of lipogenesis
- NADPH
- NADP+
Regulation of lipogenesis
- activated by insulin
- deactivated by glucagon epinephrine
LDL
Low Density, more lipid than protein
HDL
High density protein + lipoprotein, low lipid content
VLDL
Very Low Density, high lipid content, low protein
excess fat stored in
Lipocytes
Location of de nobo synthesis of cholesterol
- liver
- secondary sites: adrenal cortex, ovaries and testes
Energetic cost of de novo synthesis of cholesterol
18 ATP
Enzyme in de novo synthesis of cholesterol
HMG CoA synthase
Regulating step of de novo synthesis of cholesterol
HMG CoA to mevalonade
HMG CoA inhibited by
Statins
Location of HMG CoA enzyme
- Endoplasmic reticulum
How many steps needed to convert squaline to cholesterol
19
Half life of HMG - CoA
2 hours