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Biochemistry > Carbohydrate and glucose management > Flashcards

Carbohydrate and glucose management Flashcards

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1
Q

How is the biochemical network regulated?

A
  • Lifestyle
  • Hormones
  • Metabolite level
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2
Q

How much glucose is used everyday?

A

160-200 g

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3
Q

How much glucose does the brain use everyday?

A

120-150 g

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4
Q

How much glucose is stored as glycogen?

A

190 g

This is depleted during one day of fasting

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5
Q

What cannot not happen in brain cells to produce energy?

What process of the biochemical pathways?

A

Beta-oxidation

Because the myelin sheets cannot absorb long chain fatty acids

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6
Q

Which two energy sources does the brain use?

A
  • Glucose
  • Ketone bodies
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7
Q

What are three types of stereo-isomer sugars?

Stereo-isomers have the same chemical formula

A
  • Glucose
  • Mannose
  • Galactose
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8
Q

What glucose formations are more common in the body than linear D-glucose?

Linear glucose: <0.1%

A

Cyclic D-glucopyranose

Alpha: 36%, Beta: 63%

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9
Q

What type of glucose is not metabolized in the body?

A

Beta-L-glucose

Emzymes can metabolize Beta-D-glucose

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10
Q

Where do carbohydrates come from?

A
  • Starch
  • Plants
  • Dairy
  • Processed food
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11
Q

Which enzymes degrades starch?

A

Alpha-amylase

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12
Q

Which bonds does alpha-amylase cut?

A

Alpha 1,4 bonds

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13
Q

Where is Alpha amylase released from?

A
  • Salivary glands
  • Pancreas

Amylase is released in the pancreas together with HCO3-

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14
Q

Which compounds is starch degraded into?

A
  • Trisaccharides
  • Monosaccharides
  • Maltose
  • Isomaltose

Maltose and isomaltose degraded by maltase and isomaltase

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15
Q

Which compound are maltase and isomaltase degraded into?

A

Glucose

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16
Q

Which compounds is sucrose degraded into?

A
  • Glucose
  • Fructose
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17
Q

Which compounds is lactose degraded into?

A
  • Glucose
  • Galactose
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18
Q

Which carbohydrate cannot be metabolized?

A

Fiber

Cellulose cannot be metabolized

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19
Q

How does fructose enter the cell?

Passively or actively?

A

Passively

Through GLUT5

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20
Q

How can glucose enter the cell?

A
  • Passively
  • Actively
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21
Q

How does galactose enter the cell?

A

Actively

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22
Q

What compound does the active transporter need to allow glucose and galactose to enter the cell?

A

Na+

3 Na+ is actively moved out the cell by Na+-ATPase in exchange for 2 K+

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23
Q

Which enzyme is missing to cut beta 1,4 bonds in lactose when people have lactose intolerance?

A

Lactase

Lactose increases in the intestine, raising the osmotic effect

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24
Q

What is the name for the inability to process galactose properly?

A

Galactosemia

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25
Which enzyme do people lack with nonclassical galactosemia?
galatokinase
26
Which toxic compound is produced in nonclassical galactosemia?
Galactitol | Causes: Jaundice, enlarged liver and kidney damage
27
What enzyme is lacking in classical galactosemia?
Uridylyltransferase | Prevents ATP production as galactose-1-phosphate gets all phosphate
28
Which types of fuctosemia are there?
* Fructokinase * Aldolase B | Excess fructose excreted, ATP
29
To which group does amylase belong?
Glucosidases
30
What is the main energy source in the muscle?
Glycogen
31
How is energy produced from glycogen?
1. Glycogen 2. glucose-1-phosphate 3. glucose-6-phosphate (lactate/ATP/Co2)
32
Which enzyme is mainly involved in glycogen production
glycogen synthase
33
Which enzyme is mainly involved in glucose production from glycogen
Glycogen phosphorylase
34
Making glycogen branches | Which enzymes
1. Glycogen synthase 2. 4,6 transferase
35
Making glucose from glycogen
1. Glycogen phosphorylase 2. 4,4 transferase 3. Alpha-1,6-glucosidase
36
How is glucogen regulated in the muscle?
* Insulin * Epinephrine * Physical activity
37
How is glycogen regulated in the liver?
* Insulin * Glucagon * Epinephrine
38
Which enzyme is produced when glucagon or epinephrine are released? | Activation trough G protein mechanism
Glycogen phosphorylase
39
Which enzyme is activated when insulin is released?
Glycogen synthase
40
Which enzyme activates glycogen phosphorylase and inactivate glycogen synthase?
Active protein kinase | Activated through cAMP by G protein
41
Which enzyme activates glycogen phosphorylase itself? | It adds a phosphor group
Phosphorylase kinase | Kinase adds phophates ## Footnote Should look at the powerpoint!!!! slide no. 28 important
42
How is muscle phosphorylase regulated?
* Allosterically * phosphorylation by external control | Allosteric: By release of phosphate from ATP from the muscles. ## Footnote LOOK AT SLIDE 28!!!
43
Why does liver glycolysis increase when insulin is released?
?????
44
Which pituitary hormone stimulates the release of cortisol and epinephrine?
Adrenocorticotropic hormone | In the cortex of the adrenal glands
45
Which neurotransmitter/hormone is released from the autonomic nervous system?
Norepinephrine
46
Which pancreatic cells react upon low glucose in the blood?
Alpha-cells | They release glucagon
47
Which cells produce insulin?
Pancreatic beta-cells
48
Which ion stimulates the production of insulin in the beta-cell?
Calcium ions | K+ exits the cell by the produced ATP from glucose in the cell. Ca enter
49
Which glucose transporter facilitates fructose? | Think about F
GLUT5
50
Which tissues have GLUT4 transporters?
* Adipose tissue * Skeletal muscle * Heart muscle | GLUT4 is insulin sensitive
51
What transporter facilitates the brain with glucose?
GLUT3 | GLUT3 has high affinity for glucose (3 looks like a brain)
52
Locations of the GLUT2 transporter?
* Liver * Kidney * Pancreatic beta-cells * Serosal surface of intestinal mucosa | GLUT2 has low affinity for glucose: acts as glucose sensor
53
Which glucose transporter has barrier functions?
GLUT1
54
Which glucose transporter is found in erythrocytes?
GLUT1 | Think of small number=small cell
55
Which glycolysis enzyme is found in the pancreas and the liver more that other body cells?
Glucokinase | Higher Km and high Vmax
56
By which substance is hexokinase inhibited? | This does not happen for glucokinase
Glucose-6-phosphate
57
Which substance is used for energy during fasting in the liver?
Glycogen
58
Which substance is used for energy during fasting?
Glucose
59
Which substances are used to make glucose during starvation?
Alanine and other amino acids | The carbon skeletons are used and NH4+ is used in the urea cycle
60
By which enzyme is glucose produced from glucose-6-phosphate?
Glucose-6-phosphatase
61
Which organ can release glucose back into the bloodstream?
Only the liver
62
A high protein meal leads to the induction of which substance?
Glucagon | Leads to gluconeogenesis ## Footnote Nitrogen also spikes after protein rich meal
63
Which substrate is favored for gluconeogenesis?
Alanine | Alanine converted to pyruvate
64
Which other substrates besides alanine can also be used for gluconeogenesis?
* Lactate * Glycerol | Fatty acids cannot be used, they are metabolized into acetyl CoA
65
Where does gluconeogenesis occur?
Liver
66
Which enzymes liver-specific during gluconeogenesis?
* Glucose-6-phosphatase * Fructose-1,6-biphosphatase
67
Which hormone supports lipogenesis?
Insulin
68
Which hormone supports gluconeogenesis?
Glucagon
69
During lipogenesis, how is pyruvate converted into fatty acids? | Name the metabolites
1. Pyruvate 2. Acetyl CoA by pyruvate dehydrogenase 3. Citrate 4. Fatty acids | Pyruvate to acetyl CoA is irreversible
70
During gluconeogenesis, into which metabolites is pyruvate converted into?
1. Pyruvate 2. Oxaloacetate by pyruvate carboxylase 3. PEP 4. Glucose | carboxylase adds a carboxyl group
71
Which complex is activated when insulin is released?
The pyruvate dehydrogenase complex (PDC)

Biochemistry (13 decks)

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