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Foundations Of Medicine PoNF > Carbohydrates + Lipids > Flashcards

Carbohydrates + Lipids Flashcards

1
Q

Define the major carbohydrates

A
  • Monosaccharides
  • disaccharides
  • polysaccharides
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2
Q

Characteristics of Carbohydrates

A
  • Highly oxidisable
  • function to store potential energy
  • have structural + protective functions
  • contribute to cell communication
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3
Q

Monosaccharides

A
  • Glucose (glc)
  • galactose (gal)
  • fructose (fru)
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4
Q

Disaccharides (formed from monomers linked by glycosidic bonds)

A
  • Maltose
  • lactose
  • sucrose
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5
Q

What is an anomeric carbon

A
  • attached to sugar molecule
    Different anomie’s are mirror images of each other
  • Carbon #1 on glucose residue
  • stabilises the structure of glucose
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6
Q

carbohydrates in the diet

A
  • Lactose (sugar in milk)
  • sucrose (common table sugar, non reducing )
  • starch (contains two types of glucose polymer: amylose (20.25%) amylopectin (75-80%))
  • glycogen in meat
  • cellulose in plant cell walls we do not digest this)
  • ogliosacchardes
  • glucose + fructose

,

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7
Q

Polysaccharide types

A
  • Homopolysacchardes
  • heteropolysaccharides (multiple monomers)
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8
Q

Digestion of carbonycrates

A
  • Mouth: salivary amylase hydrolyses bonds of starch

(Nothing in stomach)

  • duodenum: pancreatic amylase hydrolyses bonds of starch
  • jejunum:
    1. Isomaltase: hydrolyses (a1-6) bonds
    2. Glucoamylase: removes glucose from non reducing ends
    3. Sucrase: hydrolyses sucrose
    4. Lactase: hydrolyses lactose
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9
Q

Glucokinase vs hexokinase

A

-G= low affinity for glucose but efficient enzyme
( High v max - phosphorylate glucose after meal quickly so most is trapped in liver)

-H= High affinity for glucose but not efficient enzyme
( low km - at low gl concentrated areas it can still grab glucose effectively)

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10
Q

Synthesis of glycogen

A
  1. Glycogenin binds to Glc from UDP to form 8 chain Glc
  2. Chains formed by glycogen synthase are broken by enzyme and attached to give branch points
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11
Q

Degradation of glycogen

A
  1. Monomers removed from non reducing agents
  2. Glc near branch removed by de-branching enzyme
  3. Removes 3 Glc and attached them to non reducing end (a1-6)
  4. Removes frontal Glc by breaking (a1-6) linkage
  5. Leaves unbranded chain that can be degraded or built upon.
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12
Q

Function of glycogen in liver and skeletal muscle

A

Glucose-1-phosphate → glucose-6-phosphate

Liver: glucose - 6-phosphates creates glucose which goes to blood

Skeletal muscle: phosphorylation creates ATP (muscle contraction), glycolysis creates lactate

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13
Q
  • Function of glycolysis
A
  • Catabolic pathway that saves some potential energy from glucose by forming ATP through substrate level phosphorylation
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14
Q
  • Steps of glycolysis (non-reversible)
A
  1. Phosphorylation of glucose (hexokinase) - uses 1 ATP
  2. Phosphorylation of F-6-P to F-1,6-bisP (phosphofructokinase-1) - uses 1 ATP
  3. Transfer of P from PEP to ADP (pyruvate kinase) - 2ATP produced - also produces pyruvate
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15
Q
  • Function of lactate dehydrogenase reactions
A

Reduction of pyruvate to form l-lactate

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16
Q
  • Function of pyruvate dehydrogenase reactions
A
  1. Pyrovate to acetaldehyde then ethanol
  2. Pyruvate to Acetyl CoA
17
Q
  • fate of blood lactate
A
  • Lactate ends up in citric acid Cycle to produce ATP for muscle function
18
Q
  • Precursors of gluconeogenesis
A
  • Pyruvate
    Pyruvate carboxylase
    Oxaloacetate
    malate dehydrogenase
    Pep carboxykinase
19
Q
  • Function of gluconeogenesis
A
  • When more glucose is required it is produced from other non-carbohydrate molecules
20
Q
  • process of gluconcogensis
A

Bypass reactions:
- After 3 (it is repeated H2O added )
- After 1 (it is repeated H2O added )
- After 10 it is repeated with (oxoaloacetate)

21
Q
  • Fate of galactose
A
  • Joins step 2 in conversion of glucose-6-p to fructose-6-p
22
Q
  • fate of fructose
A
  • Joins fructose-6-p conversion to fructos-1,6- bp,
  • metabolised by liver
23
Q
  • Major lipid classes and their roles
A

Fatty acids
Triacyglycerols (esters of fatty acids + glycerol - dietary fuel + insulation)
Phospholipid
Glycolipid
Steroids

24
Q

Structure of cholesterol

A
  • Hydroxyl group
  • steroid group
  • hydro carbon chain
25
Q

Function, synthesis + food sources of cholesterol

A
  • Component of cell membrane
  • precursor to other substances
  • mainly made in liver
  • found only in animal foods
26
Q

Process of lipid digestion + absorption

A
27
Q

Structure and function of eicosanoids

A

(Signaling molecule made by oxidation of fatty acids)

  • lipid class derived from 20-carbon unsaturated fatty acids + synthesized throughout the body
  • precursors for prostaglandins, thrombaxares and leukotrines
28
Q
  • How lipids are transported using lipoproteins
A
  • Transported in lipoproteins as hydrophobic lipids are insoluble in plasma
29
Q

Synthesis of free fatty acids

A
30
Q

Catabolism of fatty acids by beta-oxidation

A
  • Dehydrogenation
  • hydration
  • dehydrogenation
  • thiolysis
31
Q

Function of ketone bodies

A
  • Oxidised by mitochondria to yield 2 GTP and 22 ATP
  • transported from liver to other tissues
  • cannot be used by liver (liver has no b-ketoacyl-coa transferase
32
Q

Synthesis of ketone bodies

A
33
Q

Types of fatty acids

A
  • Saturated
    -unsaturated
    -essential fatty acids (from plants)
    -Good fats (cardiovascular) polyunsaturated
    -bad fats (cardiovascular) saturated fatty acids
    -really bad (trans fatty acids)
34
Q

What are essential fatty alcids?

A
  • Linoleic and linolenic acids
35
Q

Types of steroids

A
  • Cholesterol
  • steroid hormones
  • bile salts
36
Q

Digestion of lipids

A
  • Most tag digested in small intestine by pancreatic lipase to monoacylglycerol and two fatty acids
  • cholesterol esters digested to cholesterol + fatty acids
  • phospholipids hydrolysed to fatty acids and lysophospholipid
37
Q

Lipoproteins

A
  • chylomicrons: tag rich ~ biggest
  • VLDL: tag rich
  • LDL (cholestrol, extrahepatic tissue) - bad
  • HDL (tissue to liver) - good ~ smallest

Foundations Of Medicine PoNF (8 decks)

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