Carbohydrate Metabolism Flashcards
(45 cards)
1
Q
GLucose carrier protein in intestine and kidney
A
intestine - SGluT-1
kidney - SGluT-2
2
Q
ORS
A
- treatment for diarrhea
- contains glucose and sodium
- allows absorption of sodium to replenish body sodium chloride levels and glucose to provide energy.
3
Q
GluT1
A
- RBC, brain, kidney, colon, retina, placenta
- Glucose uptake in most of cells
4
Q
GluT2
A
- Serosal surface of intestinal cells, liver, beta cells of pancreas
- Low affinity
5
Q
GluT3
A
- Neurons, brain
- High affinity
6
Q
GluT4
A
- Skeletal, heart muscle, adipose tissue
- Insulin-mediated
7
Q
Glut5
A
- Small intestine, testis, sperms, kidney
- Fructose transporter
8
Q
GluT7
A
- Liver endoplasmic reticulum
- Glucose from ER to cytoplasm
9
Q
Glycolysis mnemonic
A
Goodness Gracious Friendly Fred Did Go By Picking Pumpkins to Prepare Pie
10
Q
Enzymes of glycolysis mnemonic
A
High Profile People Act Too Glamorous Picture Posing Every Place
11
Q
Significance of glycolysis
A
- takes place in all cells
- only source for erythrocytes
- anaerobic glycolysis useful in times of stress
- preliminary step to complete oxidation
- provides C skeletons for non essential AA and glycerol
- can be used for gluconeogenesis
12
Q
Inhibitors of glycolysis
A
Arsenate, iodoacetate - inhibit G3PDH
Flouride - inhibits enolase by removing Mg+2 - used when collecting blood fro sugar estimation
13
Q
Energy yield of glycolysis
A
Anaerobic - 2
Aerobic - 7
Complete oxidation of glucose - 32
14
Q
Regulatory enzymes of glycolysis
A
Hexokinase
Phosphofructokinase (-) by ATP and citrate (+) by AMP
Pyruvate Kinase
15
Q
Pasteur effect
A
Under aerobic conditions, glycolysis is inhibited. This inhibitory effect of oxygen on glycolysis is known as Pasteur effect.
16
Q
Warburg hypothesis
A
- cancer cells utilize energy from glycolysis and they require less oxygen
- growing tumor cells produce lactic acid which is taken to liver for gluconeogenesis - uses ATP - loss of weight (cancer cachexia)
- inhibition of glycolysis depletes cancer cells of ATP leading to their death
- works for colon cancers and lymphoma
- useful in case of multi drug resistance
17
Q
Significance of BPG
A
- 2,3 BPG binds to Hb and reduces affinity to O2 - easy unloading
- When pO2 is low, 2,3 BPG inc., favouring more unloading
- no ATP generated
18
Q
Pyruvate Dehydrogenase Complex
A
(TLC? Fuck No) TPP Lipolic acid CoA FAD+ NAD+ - Pyruvate dehydrogenase - Dihydrolipoyl transacetylase - Dihydrolipoyl dehydrogenase
19
Q
Importance of Pyruvate Dehydrogenase
A
- Completely irreversible
- Cannot synthesize glucose from fat
- 2.5 ATP
20
Q
Precursors of gluconeogenesis
A
- Pyruvate/Lactate
- Glucogenic AA (Cori’s, Cahill’s cycle)
- Glycerol
- Propionate
21
Q
Site of gluconeogenesis
A
Mainly liver, renal cortex
Partly cytoplasmic, partly mitochondrial
22
Q
AA for oxaloacetate
A
- Aspartic acid
- Asparagine
23
Q
AA for Pyruvate
A
- Alanine
- Cysteine
- Glycine
- Tryptophan
- Serine
24
Q
AA for alpha KGA
A
- Arginine
- Glutamine
- Glutamate
- Histidine
- Proline
25
AA for succinyl CoA
- Valine
- Isoleucine
- Threonine
- Methionine
26
AA for fumarate
- Tyrosine
| - Phenylalanine
27
Significance of gluconeogenesis
1. Only by liver as G6Pase is only in liver
2. Maintains blood sugar level during starvation
3. Uses 6 ATP
28
GLycerol to glucose
TAG-
Glycerol -
Glycerol 3 phosphate -
DHAP
29
Propionate to glucose
Odd chain fatty acids -
Propionyl CoA -
Methylmalonyl CoA -
Succinyl CoA
30
Regulation of gluconeogenesis
```
Pyruvate carboxylase (+) Acetyl CoA
F 1,6 Bisphosphotase (+) Citrate (-) AMP
```
31
Glycogenolysis enzymes Mnemonic
```
Powerful Thor Gave Powerful Pennies Proudly
Phosphorylase
Transferase
Glucosidase
Phosphorylase
Phosphoglyceromutase
Phosphotase
```
32
Energetics of glycogenolysis
3 ATP released for 1 glucose residue
33
Glycogenesis enzymes mnemonic
```
Grey Psychopaths Predated Sluts Tactfully
Glucokinase
Phosphoglyceromutase
UDP glucose Pyrophosphorylase
Synthase
Transglycosylase
```
34
Regulation of glycogenesis
1. Reciprocal regulation of syn. and degradation
2. Covalent modification of glycogen phosphorylase(+ phosphorylation) and glycogen synthase (+ dephosphorylation)
3. Act through cAMP
35
Liver glycogen phosphorylase
- active on phosphorylation
| - inhibited by ATP and glucose-6-phosphate
36
Types of glycogen storage diseases
```
Viagra Pills Cause A Major Hardon, Ted
1- Von Gierke's
2- Pompe's
3- Cori's
4- Anderson's
5- McArdle's
6- Her's
7- Tarui
```
37
HMP shunt intermediates mnemonic
```
Graceful and Gorgeous Gabriel Refused Refined Xylophones So Gideon Enslaved Frozen geese Forcibly
Glucose 6 P
6 phosphoGulunolactone
6 phosphoGluconate
Ribulose 5 ph
Ribose 5 ph
Xylulose 5 ph
Sedoheptulose 7 ph
Glyceraldehyde 3 ph
Erythrose 4 ph
Fructose 6 ph
Glyceraldehyde 3 ph
Fructose 6 ph
```
38
Regulation of HMP shunt
- mainly regulated by level of NADP+
- G6PDH is rate limiting, inhibited by NADPH
- non oxidative phase controlled by level of pentoses
(+) Insulin
39
Importance of HMP shunt
1. To produce NADPH and pentose phosphates for
i. Reductive biosynthesis- fatty acids, cholesterol, steroid hormones
ii. Free radical scavenging
iii. Maintain RBC membrane integrity by keeping GSH in reduced state
iv. Prevention of met-hemoglobin formation
v. Detoxification by hydroxylation
vi. Maintain the transparency of lens
vii. Bactericidal activity of macrophages
2. Ribose-5-phosphate is required for nucleic acid synthesis
40
HMP shunt operates in
1. Liver
2. Adipose tissue
3. Adrenal cortex
4. Mammary glands
5. Testes and ovaries
6. RBCs
7. Lens of eye
41
Free radical scavenging
- free radicals damage DNA, protein etc
- removed by enzyme systems containing superoxide dimutase, peroxidase, glutathione reductase
- reduced glutathione generated with help of NADPH
42
Functions of UDP glucuronic acid
It is active form of glucuronic acid
- conjugation of bilirubin
- conjugation of steroids
- conjugation of drugs to make them water soluble and easily excretable
- detoxification of environmental toxins and carcinogens
- precursor for glycosaminoglycan synthesis
43
Where is aldose reductase present and absent?
| What does it do?
Absent - liver
Present -
Retina, Eye lens, Kidney, Placenta, Peripheral nerve cells
It converts glucose to sorbitol producing 1 NADP+
44
Where is sorbitol dehydrogenase found? What does it do?
Seminal vesicles, ovaries, spleen
| Converts sorbitol to fructose using 1 NAD+
45
Why can and why cannot fructose be used to treat Diabetes Mellitus
- More easily absorbed than glucose as it is not controlled by insulin
- leads to inc. in fatty acid synthesis, raised serum triglycerides, high LDL
- atherogenic
- phosphorylation of fructose also uses ATP leading to low Pi
- this removes inhibition on adenosine deaminase
- more uric acid produced
