protein metabolism

Question 1

what is meant when it is said that amino acids r glucogenic? ketogenic?

Answer 1

if they produce Acetyl Coa which can be used to make ketone bodies>ketogenic
if they produce products than can be used for gluconeogenesis>glucogenic

Question 2

what is meant by the term “turnover”

how much is the total protein turnover in humans?

Answer 2

all body proteins undergo continuous breakdown and synthesis. it is not a random process.

-300-400g per day

Question 3

what is the average half-life of a body protein?

Answer 3

80 days

Question 4

most nitrogen enters the body as________-

and leaves the body as ________

Answer 4

protein

urea

Question 5

*** RATE OF PROTEIN SYNTHESIS EQUALS DEGREDATION

Answer 5

ok

Question 6

what is the amino acid pool?

Answer 6

total amount of free aa in the body

Question 7

what is creatinine? state its function

Answer 7

breakdown product of CREATINE & CREATINE PHOSPHATE in muscle.

• we can use it as an estimate of muscle mass
• and can be used as an indicator of renal function

Question 8

during 1-2 sec of a vigorous activity, what can supply us with ATP?

Answer 8

creatine phosphate can supply the ATP.

its a very rapidly store of ATP

Question 9

***CREATINE & CREATININE R DIFFERENT

Answer 9

remember that

Question 10

describe the nitrogen balance of the body.

in what times would the body have more protein intake that output? and vise versa?

Answer 10

In heakthy adults there is a steady state between amount of N taken and lost. N-BALANCE

Positive N balance= N intake is greater than its loss (active growth,pregnancy, tissue repair)

Negative N balance= N intake is LESS than n loss (starvation, malnutrition, trauma)

Question 11

in which condition would u see heinz bodies?

Answer 11

G6PDH defiency

Question 12

amino acid functions

Answer 12

protein synthesis and synthesis of other N compounds. signalling molecules such asNO r formed too.

Question 13

what is transamination? which enzyme is involved

Answer 13

removal of NH2 from aa, via aminotransferase.

bc its transferring the NH2 group from aa to keto acid (a-ketogluterate

Question 14

What term is used to describe scarring of the liver caused by continuous long-term liver damage?

Answer 14

Cirrhosis

Question 15

during the conversion from ethanol/alchohol to acetylaldehyde which energy product is produced?

Answer 15

NADH

Question 16

Which metabolite can be measured in urine to provide an estimate of muscle mass?

Answer 16

Creatinine is a breakdown product of creatine phosphate and creatine in muscle. It is usually produced at a fairly constant rate and filtered by kidneys into urine. For this reason urine creatinine over a 24 hour period can be used as an estimate of muscle mass.

Question 17

Which effect would the hormone insulin have on the process of protein degradation (proteolysis)?

Answer 17

Decrease in activity

Think of Insulin as the “hormone of plenty”. If you have just eaten a meal there would be sufficient amino acids derived from the ingested protein so there would be no need to degrade body protein.

Question 18

Proline is not dietary essential amino acid

Answer 18

Ok

Question 19

From which amino acid does the body synthesise the hormone adrenaline?

Answer 19

Tyrosine

Question 20

Which keto acid is used by aminotransferase enzymes to funnel the amino group of other amino acids to glutamate?

Answer 20

α-ketoglutarate

Question 21

Which aminotransferase enzyme is routinely measured as part of liver function test?

Answer 21

Alanine aminotransferase and aspartate amino transferase enzymes (ALT and AST) are routinely used as part of a liver function test. These liver enzymes are not normally found in plasma so their presence in a blood test gives an indication of liver damage.

Question 22

Which amino acid is utilised for the transport of ammonia from peripheral tissues to the liver?

Answer 22

Alanine

Ammonia is therefore used to transaminate pyruvate to produce alanine. The alanine is then transported in blood to the liver where it is converted back to pyruvate by transamination.

Question 23

Which of the following amino acids is NOT dietary essential?

Answer 23

Proline

Question 24

why is deamination important in terms of different types of aa isomer (hint: D&L form)?

Answer 24

important for dealing with dietary D aa. found in bacteria and plants.

normally, the aa we consume in the bulk of our food and the aa we use to make protein r the L-amino acid form.
so metabolic pathways cannot deal with the D form, so we need to deaminate them before we can use them. otherwise the protein would be non-functional and structurally abnormal.

Question 25

name 3 enzymes used in deamination?

Answer 25

• aa oxidase
• glutaminase
• glutamate dehydrogenease

Question 26

what happens to the ammonia and ammonium ions that r releases during protein catabolism?

Answer 26

must be removed,
converted to urea via the urea cycle
ore excreted directly in the urine

Question 27

** at physiological PH ammonia (NH3) is converted to ammonium ions (NH4)

Answer 27

ok

Question 28

if urine sample is left for a while, it’ll develop this ammonia smell, what caused this to happen?

Answer 28

BACTERIA have the enzymes top break down the urea to release NH3!

causing the ammonia smell

Question 29

how do we synthesise urea?

Answer 29

via the urea cycle (needs co2 to work)

-when glutamic acid was transaminated, ammonia was released…it enters the mitochondria along w/ co2 (from the krebs cycle) to enter the urea cycle. and shit happens which releases urea.

Question 30

function of urea cycle and where does it occur?and how is it controlled

Answer 30

allows the n groups of amino acids to dispose the body in the form of urea.

controlled via 5 enzymes!

Question 31

what is the refeeding syndrome? why does it occur.

Answer 31

ok, so the enzymes that regulate the urea cycle r upregulted or downregualted depending on the body intake of protein.
itha high protein intake» upregulated
itha low protein intake» downregualted

*when u suddenly give starved patients a protein rich diet, the urea cycle hasn’t got the capacity to deal with the ammonia released. (bc all the enzymes have been downregulated) **and this will lead to accumulation of ammonia causing AMMONIA TOXICITY!

Question 32

u give a starved person a high protein diet, they developed ammonia toxicity, why doe this happen?

Answer 32

*when u suddenly give starved patients a protein rich diet, the urea cycle hasn’t got the capacity to deal with the ammonia released. (bc all the enzymes have been downregulated) **and this will lead to accumulation of ammonia causing AMMONIA TOXICITY!

Question 33

why is ammonia so toxic to cells?

Answer 33

• it is readily diffusible
• extremely toxic to the brain since it can cross the blood brain barrier
• interferes with krebs cycle by reacting w/ a-keogluterate

Question 34

how much should we keep blood ammonia?

Answer 34

25-40 mmol/L

Question 35

what r the 2 ways in which we can get rid of ammonia safely from tissues?

Answer 35

• glutamine>ammonia + glutamate= Glutamine

- alanine> ammonia + pyruvate=alanine

Question 36

how can u treat overdose of paracetamol?

why should u act FAST?

Answer 36

Because effects r IRREVERSIBLE

give antidote ACETYLCYSTINE w/ in 8HRS!

-works by restoring glutathione levels

SOOO..
Acetylcysteine serves as a prodrug to ‘L-cysteine.’
it’ll act as a PRECURSOR for more glutsthione to be made.

(remember glutathione is a tripeptide!
Glycine-Cys-Glutamate)

Question 37

difference btw marasmus and Kwashiorkor?

Answer 37

Marasmus> caused by energy deficiency! > explains muscle wasting

Kwashkiorkor> develops in those with sufficient energy nut insufficient protein intake> explain edema