Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Y1 - MEH > Protein And Amino Acid Metabolism > Flashcards

Protein And Amino Acid Metabolism Flashcards

1
Q

What is Creatinine?

A

A breakdown product/metabolite of Creatine and Creatine phosphate in muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the function of Creatinine?

A

Has no metabolic function so is excreted by the kidneys in the urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Clinical relevance of Creatinine levels in the urine

A

Provides an estimate of muscle mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Clinical relevance of creatinine plasma levels

A

Indicate renal function
High plasma levels and low urine levels = poor blood filtration in kidneys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Nitrogen (N) Balance?

A

When rate of nitrogen intake matches the rate of nitrogen lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is meant by a positive N Balance?

A

More nitrogen is taken in than is lost
Increase in total body protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When is it normal to have a positive N Balance?

A

Growth
Pregnancy
Adult recovering from malnutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is meant by a Negative N Balance?

A

The loss of N is greater than the intake of N
Net loss of total body protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When is a Negative N balance normal?

A

It is NEVER Normal
It indicates trauma, infection or malnutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is protein turnover?

A

The constant breakdown and re-synthesis of proteins in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a glucogenic amino acid?

A

An amino acid who’s carbon chain can undergo GLUCONEOGENESIS to produce glucose to release energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a ketogenic amino acid?

A

An amino acid who’s carbon Skelton goes into produce Ketone bodies (ketogenesis) and fatty acids to release energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Give an example of a Glucogenic amino acid

A

Alanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give an example of a Ketogenic amino acid

A

Leucine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give an example of an amino acid which is both glucogenic and ketogenic

A

Phenylalanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When are protein reserves used for energy?

A

During starvation/extreme stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What type of molecules regulate mobilisation of protein reserves for energy?

A

Hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What hormones stimulate protein synthesis and inhibit proteolysis?

A

Insulin and GH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which hormone inhibits protein synthesis and simulated proteolysis?

A

Glucocorticoids (Cortisol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does excess Cortisol lead to the purple striae in the skin in Cushing’s Syndrome?

A

Cortisol stimulates proteolysis
Proteins in skin broken down
Skin weakens forming striae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How are proteins metabolised?

A

Digested to free amino acids
Either Used to produce cellular proteins or enter the liver
Amino group removed and excreted as urea in urine
Carbon Skeleton used to produce energy, the way this occurs depends on whether the amino acid was glucogenic or ketogenic

22
Q

What are the 9 essential amino acids?

A

Isoleucine
Lysine
Threonine
Histidine
Leucine
Methionine
Phenylalanine
Tryptophan
Valine

23
Q

What are the 3 Conditionally essential amino acids?

A

Arginine
Tyrosine
Cysteine

24
Q

Why can tyrosine be a conditionally essential amino acid?

A

Tyrosine can be made from Phenylalanine
If diet is low in phenylalanine Tyrosine becomes Conditionally essential

25
Why can cysteine be a conditionally essential amino acid?
Cysteine can be synthesised from Methionine If diet is low in Methionine cysteine is conditionally essential
26
Why can arginine be a conditionally essential amino acid ?
Small amounts of arginine can be made Becomes essential in periods of active growth like pregnancy
27
What are the 2 ways by which the amino group of amino acids can be removed to allow the carbon skeleton to be utilised in oxidative metabolism?
Transamination Deamination
28
What happens to the nitrogen removed from an amino acid?
Incorporated into other compounds Excreted as urea
29
What is transamination?
Transfer of the amino groups to another molecule
30
What is the name of the enzyme which allows for transamination to occur?
Aminotransferase
31
What are the 2 key aminotransferases?
Alanine aminotransferase (ALT) Aspartate aminotransferase (AST)
32
What is the clinical significance of the levels of ALT and AST?
Part of the liver function test Levels high in conditions that cause extensive cell necrosis
33
What is Deamination?
When the amino group is removed and forms free ammonia (Normally happens in liver and kidney)
34
What is the fate of free ammonia?
Converted to urea which is non toxic and inert Ammonia is very toxic
35
What is the purpose of the urea cycle?
Safely convert ammonia into urea for excretion in urine
36
Where does the urea cycle take place?
Liver
37
How many enzymes are involved in the urea cycle?
5
38
How does a high protein diet affect the levels of the 5 enzymes involved in the urea cycle?
Increases the enzyme levels since more amino acids are being taken in so more ammonia is going to be produced
39
How does a low protein diet affect the levels of the 5 enzymes involved in the urea cycle?
Low protein = less amino acids so less ammonia is going to be produced Therefore the enzyme levels are reduced
40
How is ammonia toxic?
Readily diffusible Causes alkaline blood Alters blood brain barrier Interfere with Krebs cycle
41
What is Phenylketonuria?
Autosomal recessive Genetic defect in amino acid metabolism, causes accumulation of phenylalanine in tissues, blood and urine On chromosome 12
42
What enzyme is deficient in Phenylketonuria (PKU)?
Phenylalanine hydroxylase
43
What substances build up as a result of Phenylketonuria?
Phenylalanine Phenylketones
44
What is not produced as a result of a phenylalanine hydroxylase deficiency in Phenylketonuria?
Tyrosine
45
What is the significance of being deficient in Tyrosine?
Can’t synthesise: Adrenaline Noradrenaline Dopamine Thyroid hormones
46
What are the symptoms of PKU?
Severe intellectual disability Microcephaly Seizure
47
How is PKU Treated?
Avoid high protein foods Diet with low phenylalanine and high tyrosine
48
What is Homocystinurias?
Autosomal recessive disorder A problem breaking down methionine causing excess homocysteine to be excreted in urine as homocystine Homocysteine is what would be present in the plasma (homocystine is the oxidised form of homocysteine formed from methionine being metabolised)
49
Which enzyme is defective in Homocystinurias?
Cystathionine B-synthase
50
What problems does Homocystinurias cause?
Problems with: Connective tissues Muscles CNS CVS
51
How does deficiency of cystathionine B-synthase cause disease?
Homocysteine and it’s metabolites accumulate causing disease symptoms

Y1 - MEH (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions