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CHEM 101 > Lipid and amino acid metabolism > Flashcards

Lipid and amino acid metabolism Flashcards

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1
Q

What are lipids composed of

A

Carbon, hydrogen, oxygen

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2
Q

Common types of lipids

A

Triglyceride or neutral fat

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3
Q

Triglycerides can be removed from

A

 Herbivores do not eat a lot of fat
 Convert carbohydrates in excess to fat
 Triglycerides can be removed from blood by liver and structurally altered

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4
Q

Lipolysis

A

Breakdown of fats

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5
Q

Triglycerides hydrolyzed to

A

1 glycerol
3 fatty acid chains

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6
Q

If there is a balance between carbohydrate and fat metabolism in triglyceredie metabolism

A

Most acetyl CoA produced by fatty acid metabolism goes through Krebs cycle

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7
Q

Route of triglyceride metabolism

A

Pyruvate → Acetyl CoA → Krebs Cycle
 Pyruvate → glucose synthesis

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8
Q

Triglyceride metabolism steps

A

Glycerol catabolized to
dihydroxyacetone phosphate in cytoplasm
 Enters glycolysis and is converted to pyruvate
Breakdown of fatty acids occurs in mitochondria
Beta oxidation
Acetyl CoA enters Krebs cycle
 NADH and FADH2 enter the electron transport chain

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9
Q

Beta oxidation is

A

pathway in which a fatty acid chain is broken into acetyl CoA molecules

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10
Q

Triglyceride metabolism produces

A

FADH2 and NADH

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11
Q

Complete oxidation of what in triglyceride metabolism

A

Complete oxidation of one 18 carbon fatty acid chain is 148 ATP

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12
Q

Fat metabolization

A

 Fat is more difficult to mobilize so is used as a reserve energy source
 Lipids can be stored in fatty tissue to protect health when food supplies are low
 When body cells need fatty acids for energy hormones such as epinephrine interact with adipose tissue
 Epinephrine stimulates hydrolysis of triglycerides
 Glycerol and fatty acids enter the bloodstream
 Mobilized fatty acids form a lipoprotein with serum albumin in blood
 Transported where they are needed
 Glycerol is water soluble so dissolves in blood and is transported

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13
Q

Fatty acids stored in triglycerides are called on as energy sources from

A

By resting muscle and liver cells:
conserves the body’s glycogen stores and glucose for brain cells and red blood cells

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14
Q

What becomes the primary energy source during metabolsim

A

Fatty acids

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15
Q

What happens during Fasting metabolism

A

Level of glycolysis decreases
 Reduced amount of oxaloacetate is synthesized
 Oxaloacetate is used to make glucose
 Lack of oxaloacetate reduces activity of Krebs cycle
 More acetyl CoA is produced by fatty acid breakdown than can be processed through Krebs cycle

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16
Q

What happens to ketones during fasting

A

Excess acetyl CoA is converted into
ketone bodies in liver:
 Acetoacetic acid, acetone, beta-
hydroxybutyric acid
 Ketone bodies carried by blood to brain, heart and skeletal muscle
 Ketone bodies can be oxidized for energy

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17
Q

Diabetes mellitus

A

Produces an imbalance in
carbohydrate and lipid metabolism
 Not enough glucose enters cells to meet energy needs
 Results in increased fatty acid metabolism
 Excess acetyl CoA
 Increase in ketone bodies in blood

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18
Q

Ketonemia

A

An elevated level of ketone bodies in blood

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19
Q

Ketosis

A

ketonemia, ketonuria, and
acetone breath existing
simultaneously

20
Q

ketonuria

A

presence of ketone bodies in urine

21
Q

Acetone breath

A

concentration of acetone in blood is so high it is expelled through lungs

22
Q

Ketoacidosis

A

low blood pH due to elevated levels of ketone bodies

23
Q

Triglyceride synthesis process

A

 Excess energy-producing nutrients are converted to fatty acids and then to body fat
 Conversion reactions occur in liver, adipose tissue and mammary glands
 Fatty acid biosynthesis occurs in the cytoplasm
 Fatty acid chains are built up 2 carbons at a time
 Fatty acids then incorporated into triglycerides

24
Q

Triglyceride synthesis is stored in and requires how much energy

A

 Requires energy
 Store in form of fat in adipose tissues

25
Q

What can the liver do during triglyceride synthesis

A

 Liver can modify body fats
 Can lengthen or shorten fatty acid chains
 Can saturate or unsaturate fatty acid chains

26
Q

Most important function of amino acids

A

Building blocks for the synthesis of proteins

27
Q

Amino acid pool is

A

total supply of amino acids in the body
 digestion of food, degradation of tissue, and synthesis in the liver

28
Q

Protein turnover

A

when body proteins are hydrolyzed and resynthesized

29
Q

Amino acid metabolism

A

Amino acids in excess of immediate body requirements are not stored, but degraded
 Nitrogen atoms are converted or excreted

30
Q

Carbon skeletons are used for

A

Energy production
Synthesis of glucose
Conversion to triglycerides

31
Q

The nitrogen of amino acids is either

A

Excreted
 Used to synthesize other compounds
Bases for nucleotides, heme structures, neurotransmitters

32
Q

Three stages to nitrogen catabolism

A

Transamination
Deamination
Urea formation

33
Q

Transamination is and what happens during

A

Transamination – enzyme-catalyzed transfer of an amino group to a keto acid
 Enzymes are called transaminases
 Result is a new amino acid
 Process occurs in mitochondria

34
Q

Deamination is and what happens during

A

 Deamination – process resulting in removal of an amino group
 Ammonia (NH3),a keto acid, and NADH are produced
 Keto acid can be used in:
 Transamination reaction
 Enter the Krebs cycle
 Since ammonia is toxic most deamination reactions occur in the liver

35
Q

Urea formation is and occurs in

A

 Urea cycle occurs in the liver
 Ammonia is converted to urea
 Urea diffuses out of liver into blood
 Kidneys filter urea out
 Urea is excreted in urine

36
Q

Uremia

A

Buildup of urea in blood

37
Q

What can happen during liver and kidney failure

A

 If kidney is diseased it may not excrete urea effectively
 Uremia – buildup of urea in blood
 High blood urea nitrogen (BUN) level
 If liver is diseased it may not be converting ammonia to urea
 Increased ammonia level
 Low blood urea nitrogen level

38
Q

If energy is not immediately needed during amino acid catabolism

A

Carbon skeletons can be converted to glucose or fat

39
Q

What happens after transamination or deamination

A

 After transamination or deamination
the remaining carbon skeleton is
degraded
 Pyruvate, acetyl CoA, acetoacetyl CoA, or intermediates of Krebs cycle
 Can be used to produce energy

40
Q

Glucogenic amino acids

A

carbon skeleton is degraded to pyruvate or intermediate of Krebs cycle
 Can be used to make glucose

41
Q

Ketogenic amino acid

A

carbon skeleton is degraded to acetyl CoA or acetoacetyl CoA
 Cannot be converted to glucose
 Can be used to produce ketone bodies and fatty acids

42
Q

Protein biosynthesis

A

 Manufacture of new protein from nutrient building blocks important process
 Cell function would halt without continued protein synthesis
 Amino acids are joined by peptide bonds
 Instructions for building proteins is contained in DNA

43
Q

Amino acid biosynthesis

A

 Body can synthesize non-essential amino acids
 Key starting materials are intermediates of glycolysis and Krebs cycle
 Body can readjust the relative proportions of amino acids to meet needs
 Diet does not contain exact proportions required
 Essential amino acids must be included in the diet

44
Q

Stage 1 of starvation is

A

 Body lowers basal metabolic rate
 Needs less food for maintenance
 To maintain blood glucose levels, body uses glycogen stores in liver
 Depleted after several hours
 Fat is catabolized to provide glycerol and fatty acids that can be used to produce glucose
 Ketone body levels in blood rise
 Glucose is synthesized from glucogenic amino acids
 Hydrolysis of protein supplies the amino acids

45
Q

Stage 2 of starvation includes

A

Change occurs that allows brain and other tissues to use ketones and glucose for energy
 Stored fat is primary source of energy
 Continues until fat reserves have been depleted
 Normal body functions and survivability are not threatened until the fat stores are nearly depleted

46
Q

Starvation stage 3 includes

A

 Protein becomes main energy source
 Glucose is synthesized from glucogenic amino acids
 Liver and plasma proteins are used first
 Next protein from GI tract, heart, skeletal muscles
 Structures decrease in size
 Decreased plasma proteins lead to changes in oncotic pressure
 Fluid leaks into abdominal cavity causing distention – ascites

47
Q

What happens to aniamls during starvation

A

 Malnourished animals experience a negative nitrogen balance
 Used muscle tissue to generate energy needed for vital metabolic functions

CHEM 101 (9 decks)

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