W4 Carbohydrates (Fructose Metabolism) Flashcards

1
Q

What’s the role of CHO in the body? (List 3)

A
  1. Energy provider for the body
  2. CHO is stored in the Liver/Muscles.
  3. Glycated proteins
  4. Glycosaminoglycans
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2
Q
Terminology:
What does... mean?
- Olysis = ...
- Genesis/Synthesis = ...
- Glucose Uptake = ...
- Glucose Synthesis = ... 
- Glycolysis = ...
- Gluconeogenesis = ...
A
  • Olysis = Breaking down
  • Genesis/Synthesis = Building Up
  • Glucose Uptake = Tissue take glucose from blood into them
  • Glucose Synthesis = Making glycogen from glucose
  • Glycolysis = Breaking down of glucose
  • Gluconeogenesis = Making glucose from carbon sources
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3
Q

Where does Fructose Metabolism occur?

Is fructose bad for the body?

A
  • Mainly in the Liver

- No if active but yes if sedentary

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4
Q

What does the Pancreas do?

A
  1. Secrets enzymes that help with digestion
    - Exocrine (Digestive enzymes)
    - Endocrine (body hormones into blood stream)
    - Insulin (increases glucose uptake)
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5
Q

Why is insulin important with glucose in the liver?

A
  • It increases Glucokinase volumes which change glucose into glycogen in the liver cell.
    (therefore, maintaining a higher gradient of glucose in the blood compared to the liver cell - meaning more glucose will keep entering the liver)
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6
Q

What is the importance of Blood Glucose in the brain?

A

Glucose is important for:

  • Turnover
  • Neurotransmitter Synthesis
  • 20% glucose in the brain (LOADS!)
  • Not insulin mediated (VERY GOOD)
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7
Q

“Glucose is taken in through … then either fully oxidised or converted into lactate.”

Which Glut is used in the sentence above?

A

“Glucose is taken in through Glut 3 then either fully oxidised or converted into lactate.”

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8
Q

What do Glut 1-5 do?

A

Glut 1: Sit in cell membrane & transports glucose into the cell from the blood stream.
Glut 2: Glucose Uptake, facilitates the diffusion of glucose across the cell’s membranes.
Glut 3: Facilitates the transport of glucose across the cell’s plasma.
Glut 4: Glucose Transporter, Translocated too membrane. It’s an insulin-regulated transporter to help with glucose.
Glut 5: Transports fructose from the intestinal lumen into the enterocyte via diffusion.

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9
Q

Name another way to increase glucose in a cell.

A

Calcium increases glucose in the cell (its released when the muscle is contracted).

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10
Q

What is glucose important for?

A
  1. Brain (ketones)
  2. Turnover
  3. Neurotransmitter synthesis
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11
Q

Once glucose has entered the skeletal muscle cell can it leave again?

A
  • Glucose cannot leave once it has entered because of the concentration gradient.
  • It is either stored or oxidised (used as energy)
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12
Q

Where are the main storage points for CHO? Which storage place is the biggest?

A
  • Liver & Muscles

- The liver has a bigger capacity however, there are more muscles

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13
Q

Why is insulin important in the liver?

A
  • Insulin in the liver is important because it increases Glucokinase which change glucose in to glycogen. Therefore, maintaining a lower concentration gradient in the cell so glucose keeps flooding into the liver cell.
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14
Q

Storing glycogen in the brain as astrocytes (cell in CNS) is important because…

A
  • It means the brain doesn’t have to store glycogen in the neurones but the neurones can still use the glycogen because its stored as astrocytes in the support cells.
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15
Q

What is the role of insulin in skeletal muscle cells?

A
  • Moves GLUT 4 to the membrane (which allows extra glucose into the cell)
  • This doesn’t happen in the liver!
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16
Q

Describe the 4 steps of glycogen building and 1 fact about why branch structuring is good.

A
  1. Glucose attaches to glycogenin (enzyme that acts as primer for changing glucose into glycogen)
  2. Once there is 8-10 glucose units (pro-glycogen) glycogen synthase (regulated by insulin) takes over creating macro-glycogen
  3. Then a branching enzyme starts connecting different macro-glycogen = creating a branched structure!
  4. 12 residues break off at about 7 bonds & attach to neighbour.
  5. The branch structure is space efficient meaning more glucose can be stored in glycogen!
17
Q

How is glycogen synthase regulated?

A
  • Phosphate groups block the catalytic site
  • Which means UDP-glucose cannot be converted into glycogen
  • Glycogen synthase is normally inactive but when activated by insulin protein phosphatase removes a phosphate allowing glycogen to be produced.
18
Q

What does Protein Phosphatase (enzyme) do?

What does Protein Kinase A (enzyme) do?

A
  • Protein Phosphatase removes a phosphate from the glycogen synthase process making it an active site!
  • Regulated by insulin
  • Protein Kinase A adds a phosphate from glycogen synthase process making it an inactive site!
19
Q

Can you give 3 key points about insulin (hormone)?

A
  1. It’s released after the ingestion of CHO
  2. Reduces breakdown of CHO
  3. It stimulates storage of CHO
20
Q

Can you give 3 key points about Glucagon (hormone)?

A
  1. Released after periods of no food
  2. Stimulates food breakdown
  3. Inhibit/prevents storage
21
Q

During exercise Glycolysis begins. Why during glycolysis is there no insulin produced?

A
  • Insulin is used for storage which we do not need during exercise.
  • We will want to use glucose in glycolysis to create ATP.
22
Q

What are 3 things Glycolysis generates?

What is NADP & ATP net result after glycolysis?

A
  1. ATP
  2. Co-enzymes
  3. Energy independent of oxygen
    Net results:
    - 2 molecules of NADP
    - 2 molecules of ATP
23
Q
  • PDH (Pyruvate Dehydrogenase) converts … into …
  • PDH increases the influx of … from glycolysis into the …
    Fill in the blanks
A
  • PHD (Pyruvate Dehydrogenase) converts pyruvate into Acetyl-coA.
  • PDH increases the influx of Acetyl-coA from glycolysis into the TCA cycle.
24
Q

What are 4 functions of the TCA cycle?

A
  1. Decarboxylation (eliminate a carbon acid) of Acetyl-coA
  2. ATP production
  3. FADH2 production
  4. NADH production
25
Q

During the Electron transport chain (ETC) how do electrons travel through the chain?

A
  • Electrons pass from donors to electron receptors

- Each electron receptor wants the last one more than the last!

26
Q

What is Gluconeogenesis?

A
  • It is a metabolic pathway that results in the generation of glucose.
  • Because Acetyl-coA from fatty acids cannot from glucose.
  • We want to reverse the process so we can create more glucose however, it isn’t very easy
27
Q

Gluconeogenesis:

- What is the only carbon backbone that we can use during this process?

A
  • OAA or Oxaloacetate