MMT: gluconeogenesis

Question 1

Describe the physiological significance of gluconeogenesis. List the primary precursors of gluconeogenesis

Answer 1

Helps us generate glucose to use for energy from non-carbohydrate sources, namely pyruvate, lactate, glucogenic amino acids, and glycerol

Question 2

Gluconeogenesis starts in the ___ and ends in the ___

Answer 2

Mitochondria; endoplasmic reticulum

Question 3

Name the major organs that carry out gluconeogenesis. Locate the various enzymes of gluconeogenesis in cell compartments

Answer 3

Liver and kidney cortex

Question 4

High glucagon stimulates ___ (gluconeogenesis vs glycolysis)

Answer 4

Gluconeogenesis

Question 5

high insulin stimulates ___ (gluconeogenesis vs glycolysis)

Answer 5

glycolysis

Question 6

High cortisol stimulates ___ (gluconeogenesis vs glycolysis)

Answer 6

Gluconeogenesis

Question 7

Generally, diabetes type 1 or 2 stimulates ___ (gluconeogenesis vs glycolysis)

Answer 7

gluconeogenesis

Question 8

Specify how we can make DHAP, oxaloacetate, and pyruvate to act as starters in gluconeogenesis

Answer 8

DHAP: glycerol
Oxaloacetate: some amino acids
Pyruvate: lactate and some amino acids; whole pathway will be used

Question 9

discuss how alcoholism can inhibit gluconeogenesis and lead to hypoglycemia

Answer 9

sustained ethanol concentration requires constant use of NAD+ to process it, forming a lot of NADH and not much NAD+. The lack of NAD+ and abundance of NADH drives formation of lactate as opposed to pyruvate, and makes alanine convert to lactate instead of pyruvate. As a result, these cannot enter gluconeogenesis and hypoglycemia can happen

Question 10

Describe how glycerol becomes DHAP

Answer 10

Glycerol uses glycerol kinase > glycerol phosphate, uses glycerol phosphate dehydrogenase > DHAP

Question 11

Describe how asparagine enters gluconeogenesis

Answer 11

Asn uses asparaginase > aspartate, uses transaminase > oxaloacetate

Question 12

Describe how lactate enters gluconeogenesis

Answer 12

Lactate uses lactate dehydrogenase to form pyruvate, or alanine uses alanine aminotransferase to become pyruvate

Question 13

Name the enzymes and reactions that replace pyruvate kinase in gluconeogenesis

Answer 13

Pyruvate +Pyruvate carboxylase (uses biotin) > OAA
OAA + PEP carboxykinase (decarboxylation and phosphorylation) > PEP

Question 14

PEP carboxykinase: reaction is catalyzes, glycolytic enzyme it replaces, energy source,

Answer 14

OAA > phosphoenol pyruvate

replaces
Pyruvate kinase

Decarboxylation and phosphorylation

Question 15

Name the enzyme and reaction that replaces PFK. does it produce ATP?

Answer 15

F1,6BP + fructose 1,6 phosphatase > F6P

Allosterically regulated
Does not produce ATP

Question 16

___ drives unfavorable reactions

Answer 16

Decarboxylation

Question 17

Name the enzyme and traction that replaces hexokinase

Answer 17

G6P + glucose-6-phosphatase > glucose

Does not produce ATP

Question 18

Pyruvate carboxylase is a ___ enzyme

Answer 18

Mitochondrial

Question 19

Specify the source of energy used for gluconeogenesis.

Answer 19

ATP from fatty acid beta oxidation, TCA and oxidative phosphorylation

Question 20

Describe the coordinated control of the enzymes in glycolysis and gluconeogenesis.

Answer 20

-High fructose 2,6 biphosphate can activate PFK (glycolysis) and inhibit fructose 1,6 bisphosphatase (gluconeogenesis)

-largely regulated by high vs low energy charge; things like ATP, acetyl CoA, and citrate signal high energy charge (less glycolysis, more gluconeogenesis) and low energy charge signals glycolysis

Question 21

what would happen if we ran glycolysis and gluconeogenesis at the same time

Answer 21

Cells in the muscle may run glycolysis at the same time as gluconeogenesis runs in the liver. Glucose enters the muscle form the blood, converts to pyruvate then lactate. Lactate enters the blood then the liver, then becomes pyruvate and then glucose. Cycle starts again.

Question 22

describe hypolactasia

Answer 22

lack of lactose. discomfort, bloating, diarrhea

Question 23

what is galactosemia? what is the treatment?

Answer 23

Unable to break down galactose

treatment is avoiding lactose

Question 24

describe classic galactosemia: deficiency type, symptoms

Answer 24

type 1; GALT deficiency. Delayed growth, jaundice, lethargy, eventual cataracts, renal failure, developmental delays

Question 25

describe non-classic galactosemia: deficiency type and symptoms

Answer 25

type 2; GALK deficiency. Cataracts and risk of E coli sepsis. Less severe as it is the first enzyme used in galactose processing.

Question 26

what is deficient in type 3 galactosemia

Answer 26

GALE

Question 27

describe fructoseria: what enzyme is deficient and what are the symptoms

Answer 27

fructokinase deficiency; fructose in the urine but otherwise asymptomatic

Question 28

describe Hereditary fructose intolerance: what is deficient, what is happening, what are the symptoms, treatment

Answer 28

aldolase B deficiency. More severe because the phosphate is trapped on the molecule. Poor feeding, jaundice, hyperglycemia. Avoid fructose or sucrose.