Lipid and amino acid metabolism

Question 1

What are lipids composed of

Answer 1

Carbon, hydrogen, oxygen

Question 2

Common types of lipids

Answer 2

Triglyceride or neutral fat

Question 3

Triglycerides can be removed from

Answer 3

 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

Question 4

Lipolysis

Answer 4

Breakdown of fats

Question 5

Triglycerides hydrolyzed to

Answer 5

1 glycerol
3 fatty acid chains

Question 6

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

Answer 6

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

Question 7

Route of triglyceride metabolism

Answer 7

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

Question 8

Triglyceride metabolism steps

Answer 8

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

Question 9

Beta oxidation is

Answer 9

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

Question 10

Triglyceride metabolism produces

Answer 10

FADH2 and NADH

Question 11

Complete oxidation of what in triglyceride metabolism

Answer 11

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

Question 12

Fat metabolization

Answer 12

 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

Question 13

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

Answer 13

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

Question 14

What becomes the primary energy source during metabolsim

Answer 14

Fatty acids

Question 15

What happens during Fasting metabolism

Answer 15

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

Question 16

What happens to ketones during fasting

Answer 16

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

Question 17

Diabetes mellitus

Answer 17

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

Question 18

Ketonemia

Answer 18

An elevated level of ketone bodies in blood

Question 19

Ketosis

Answer 19

ketonemia, ketonuria, and
acetone breath existing
simultaneously

Question 20

ketonuria

Answer 20

presence of ketone bodies in urine

Question 21

Acetone breath

Answer 21

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

Question 22

Ketoacidosis

Answer 22

low blood pH due to elevated levels of ketone bodies

Question 23

Triglyceride synthesis process

Answer 23

 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

Question 24

Triglyceride synthesis is stored in and requires how much energy

Answer 24

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

Question 25

What can the liver do during triglyceride synthesis

Answer 25

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

Question 26

Most important function of amino acids

Answer 26

Building blocks for the synthesis of proteins

Question 27

Amino acid pool is

Answer 27

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

Question 28

Protein turnover

Answer 28

when body proteins are hydrolyzed and resynthesized

Question 29

Amino acid metabolism

Answer 29

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

Question 30

Carbon skeletons are used for

Answer 30

Energy production Synthesis of glucose Conversion to triglycerides

Question 31

The nitrogen of amino acids is either

Answer 31

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

Question 32

Three stages to nitrogen catabolism

Answer 32

Transamination Deamination Urea formation

Question 33

Transamination is and what happens during

Answer 33

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

Question 34

Deamination is and what happens during

Answer 34

 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

Question 35

Urea formation is and occurs in

Answer 35

 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

Question 36

Uremia

Answer 36

Buildup of urea in blood

Question 37

What can happen during liver and kidney failure

Answer 37

 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

Question 38

If energy is not immediately needed during amino acid catabolism

Answer 38

Carbon skeletons can be converted to glucose or fat

Question 39

What happens after transamination or deamination

Answer 39

 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

Question 40

Glucogenic amino acids

Answer 40

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

Question 41

Ketogenic amino acid

Answer 41

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

Question 42

Protein biosynthesis

Answer 42

 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

Question 43

Amino acid biosynthesis

Answer 43

 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

Question 44

Stage 1 of starvation is

Answer 44

 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

Question 45

Stage 2 of starvation includes

Answer 45

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

Question 46

Starvation stage 3 includes

Answer 46

 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

Question 47

What happens to aniamls during starvation

Answer 47

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