Lipids and amino acids

Question 1

Why are amino acids which arent used as building blockd degraded?

Answer 1

No storage for amino acids

Question 2

Where is the major site for amino acid degradation?

Answer 2

Liver

Question 3

Where is proteolytic enzymes absorbed and released? What do they produce?

Answer 3

Absorbed into intestinal cells and released into blood for absorption by other tissues

Produce- single smino acids, di/tri peptides

Question 4

What happens in a protein turnover?

Answer 4

Tightly regulated
Takes place at different rates
Damaged proteins have to be removed

Question 5

Some amino acids also contain nitrogen in the side chain which can be toxic when built up. Is ammonia or ammonium the toxic part?

Answer 5

Ammonium

Question 6

After removal of the a-amino group the remaining carbon skeletons are converted into major metabolic intermediates. What can these be converted into?

Answer 6

Glucose or oxidised in the TCA cycle

Question 7

What are ketogenic amino acids degraded into?

Answer 7

• Degraded to acetyl-CoA or acetoacetyl-CoA

- Can give rise to ketpne bodies or fatty acids

Question 8

What are glycogenic amino acids degraded to?

Answer 8

• Degraded to pyruvate or TCA cycle intermediates

- Can be converted into phosphoenolpyruvate and then into glucose

Question 9

What happens to amino acids in Alcaptonuria disorder?

Answer 9

Degradation of phenylalanine and tyrosine is blocked

Question 10

What happens to amino acids in maple syrup urine disease?

What are the affects of the disease?

Answer 10

Degradation of valine, isoleucine, and leucine is blocked

Urine smells like maple syrup
Mental and physical retardation
Prevented by appropriate diet

Question 11

What happens to amino acids in phenylketonuria disorder? How can it be treated?

Answer 11

• Phenylaline accumulates in all body fluids
• Leads to severe mental retardation if untreated

Therapy- Low phenylaline diet

Question 12

What does an increased fat intake wihtout appropriate energy expenditure lead to?

Answer 12

• Increase in number of adipocytes
• More fat in adipocytes
• Obesity

Question 13

What does control of energy balance depend on?

Answer 13

-Genetically linked factors
(protein messengers regulating appetite)
-Environmental factors
(food abundance, fashionable foods)

Question 14

How is BMI calculated?

Answer 14

weight/(height)^2

Question 15

What is an:
Overweight (grade I obesity)
Clinical (grade II obesity)
Morbid (grade III obesity)
BMI number

Answer 15

Overweight 25-30kg/m2
Clinical >30kg/m2
Morbid >40kg/m2

Question 16

What is diabetes mellitus associated with?

Answer 16

Obesity

Question 17

List medical complications associated with obesity?

Answer 17

Coronary heart disease
Hypertension
Stroke
Arthritis
Gall bladder disease

Question 18

What polyunsaturated fatty acids can not be made by the body?

Answer 18

Linoleic acid, Linolenic acid, arachidonic acid

Question 19

What are some fat soluble lipids?

Answer 19

Vitamins- A, D, E, K

Question 20

• Main energy source in adipose tissue
• Comapact (dont require concomitant storage of water)
• Hydrophoic
• High energy yield per gram

What is this?

Answer 20

Triglycerides

Question 21

What does aliphatic mean?

Answer 21

No ring structure

Question 22

What are the main products of fat digestion?

Answer 22

Glycerol
Fatty acids
Monoglycerides

Question 23

Where do short and medium length fatty acids enter?

Answer 23

Portal blood

Question 24

Where do longer chain FAs and monoglycerides go?

Answer 24

Re-synthesised to triglycerides

Question 25

What are coated with a layer of protein, phospholipid and cholestoral

Answer 25

Chylomicrons

Question 26

Where do chylomicrons enter the body?

Answer 26

Lymph, then the blood stream

Question 27

At muscle and adipose tissue what happens to chylomicrons?

Answer 27

Attacked and cleaved by lipoprotein lipases

Question 28

What happens to free fatty acids?

Answer 28

- Resynthesised into triacylglycerols | - Oxidised to provide energy in muscle

Question 29

What is lipolysis?

Answer 29

Breakdown of lipids

Question 30

In lipolysis of stored fat what happens in the initial cleavage by hormone sensitive lipase?

Answer 30

Releases free fatty acids and glycerol, occurs when energy is released

Question 31

What must happen before fatty acids can be oxidised to generate energy? Where does it occur

Answer 31

They have to be converted to CoA derivatives In the cytoplasm

Question 32

Where does further oxidation of fatty acids occur? How does this happen

Answer 32

In the mitochondrial matrix Special carrier mechanism- The carnitine shuttle

Question 33

What happens during the carnitine shuttle?

Answer 33

Fatty acids are transferred from acyl-CoA to carnitine The machanism facilitates antipode of acyl-carnitine into the mitochondrion and carnitine out

Question 34

Where is the acyl-carnitine transporter located?

Answer 34

Inner membrane

Question 35

What is the net result of the carnitine shuttle?

Answer 35

acyl-CoA located in the mitochondriol matrix

Question 36

Where does beta oxidation take place | How many steps in this cycle?

Answer 36

Mitochondrial matrix | Four steps

Question 37

What are the products of the B oxidation cycle?

Answer 37

1 acetyl CoA 1 FADH2 1 NADH + H+ 1 fatty acyl-CoA, shortened by 2 carbon atoms

Question 38

How many times doe sthe b oxidation cycle occur?

Answer 38

8 times

Question 39

What happens during the breakdown of glycerol?

Answer 39

Activated by glycerol-3-phosphate by glycerol kinase Dehydrogenated to dihydroxyacetone phosphate

Question 40

What is the other name for fatty acid synthesis?

Answer 40

Lipogenesis

Question 41

Where does de novo synthesis of fatty acids mainly occur?

Answer 41

Liver, kidney, mammary glands, adipose tissue and brain

Question 42

What kind of process is lipogenesis?

Answer 42

Reductive

Question 43

What is the translation of post prandial?

Answer 43

After food

Question 44

What happens during the prolonged period of fasting?

Answer 44

Glycogen depleted, utilisation of other energy sources