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Biochemistry > Carbohydrate and glucose management > Flashcards

Carbohydrate and glucose management Flashcards

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
Q

Which enzyme do people lack with nonclassical galactosemia?

A

galatokinase

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26
Q

Which toxic compound is produced in nonclassical galactosemia?

A

Galactitol

Causes: Jaundice, enlarged liver and kidney damage

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27
Q

What enzyme is lacking in classical galactosemia?

A

Uridylyltransferase

Prevents ATP production as galactose-1-phosphate gets all phosphate

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28
Q

Which types of fuctosemia are there?

A
  • Fructokinase
  • Aldolase B

Excess fructose excreted, ATP

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29
Q

To which group does amylase belong?

A

Glucosidases

30
Q

What is the main energy source in the muscle?

A

Glycogen

31
Q

How is energy produced from glycogen?

A
  1. Glycogen
  2. glucose-1-phosphate
  3. glucose-6-phosphate (lactate/ATP/Co2)
32
Q

Which enzyme is mainly involved in glycogen production

A

glycogen synthase

33
Q

Which enzyme is mainly involved in glucose production from glycogen

A

Glycogen phosphorylase

34
Q

Making glycogen branches

Which enzymes

A
  1. Glycogen synthase
  2. 4,6 transferase
35
Q

Making glucose from glycogen

A
  1. Glycogen phosphorylase
  2. 4,4 transferase
  3. Alpha-1,6-glucosidase
36
Q

How is glucogen regulated in the muscle?

A
  • Insulin
  • Epinephrine
  • Physical activity
37
Q

How is glycogen regulated in the liver?

A
  • Insulin
  • Glucagon
  • Epinephrine
38
Q

Which enzyme is produced when glucagon or epinephrine are released?

Activation trough G protein mechanism

A

Glycogen phosphorylase

39
Q

Which enzyme is activated when insulin is released?

A

Glycogen synthase

40
Q

Which enzyme activates glycogen phosphorylase and inactivate glycogen synthase?

A

Active protein kinase

Activated through cAMP by G protein

41
Q

Which enzyme activates glycogen phosphorylase itself?

It adds a phosphor group

A

Phosphorylase kinase

Kinase adds phophates

Should look at the powerpoint!!!! slide no. 28 important

42
Q

How is muscle phosphorylase regulated?

A
  • Allosterically
  • phosphorylation by external control

Allosteric: By release of phosphate from ATP from the muscles.

LOOK AT SLIDE 28!!!

43
Q

Why does liver glycolysis increase when insulin is released?

A

?????

44
Q

Which pituitary hormone stimulates the release of cortisol and epinephrine?

A

Adrenocorticotropic hormone

In the cortex of the adrenal glands

45
Q

Which neurotransmitter/hormone is released from the autonomic nervous system?

A

Norepinephrine

46
Q

Which pancreatic cells react upon low glucose in the blood?

A

Alpha-cells

They release glucagon

47
Q

Which cells produce insulin?

A

Pancreatic beta-cells

48
Q

Which ion stimulates the production of insulin in the beta-cell?

A

Calcium ions

K+ exits the cell by the produced ATP from glucose in the cell. Ca enter

49
Q

Which glucose transporter facilitates fructose?

Think about F

A

GLUT5

50
Q

Which tissues have GLUT4 transporters?

A
  • Adipose tissue
  • Skeletal muscle
  • Heart muscle

GLUT4 is insulin sensitive

51
Q

What transporter facilitates the brain with glucose?

A

GLUT3

GLUT3 has high affinity for glucose (3 looks like a brain)

52
Q

Locations of the GLUT2 transporter?

A
  • Liver
  • Kidney
  • Pancreatic beta-cells
  • Serosal surface of intestinal mucosa

GLUT2 has low affinity for glucose: acts as glucose sensor

53
Q

Which glucose transporter has barrier functions?

A

GLUT1

54
Q

Which glucose transporter is found in erythrocytes?

A

GLUT1

Think of small number=small cell

55
Q

Which glycolysis enzyme is found in the pancreas and the liver more that other body cells?

A

Glucokinase

Higher Km and high Vmax

56
Q

By which substance is hexokinase inhibited?

This does not happen for glucokinase

A

Glucose-6-phosphate

57
Q

Which substance is used for energy during fasting in the liver?

A

Glycogen

58
Q

Which substance is used for energy during fasting?

A

Glucose

59
Q

Which substances are used to make glucose during starvation?

A

Alanine and other amino acids

The carbon skeletons are used and NH4+ is used in the urea cycle

60
Q

By which enzyme is glucose produced from glucose-6-phosphate?

A

Glucose-6-phosphatase

61
Q

Which organ can release glucose back into the bloodstream?

A

Only the liver

62
Q

A high protein meal leads to the induction of which substance?

A

Glucagon

Leads to gluconeogenesis

Nitrogen also spikes after protein rich meal

63
Q

Which substrate is favored for gluconeogenesis?

A

Alanine

Alanine converted to pyruvate

64
Q

Which other substrates besides alanine can also be used for gluconeogenesis?

A
  • Lactate
  • Glycerol

Fatty acids cannot be used, they are metabolized into acetyl CoA

65
Q

Where does gluconeogenesis occur?

A

Liver

66
Q

Which enzymes liver-specific during gluconeogenesis?

A
  • Glucose-6-phosphatase
  • Fructose-1,6-biphosphatase
67
Q

Which hormone supports lipogenesis?

A

Insulin

68
Q

Which hormone supports gluconeogenesis?

A

Glucagon

69
Q

During lipogenesis, how is pyruvate converted into fatty acids?

Name the metabolites

A
  1. Pyruvate
  2. Acetyl CoA by pyruvate dehydrogenase
  3. Citrate
  4. Fatty acids

Pyruvate to acetyl CoA is irreversible

70
Q

During gluconeogenesis, into which metabolites is pyruvate converted into?

A
  1. Pyruvate
  2. Oxaloacetate by pyruvate carboxylase
  3. PEP
  4. Glucose

carboxylase adds a carboxyl group

71
Q

Which complex is activated when insulin is released?

A

The pyruvate dehydrogenase complex (PDC)

Biochemistry (13 decks)

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