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Questions and Answers
What happens to the blood sugar level when it is decreased to approximately half?
What happens to the blood sugar level when it is decreased to approximately half?
- It decreases the heart rate.
- It increases the body's metabolism.
- It leads to coma due to lack of glucose in brain cells. (correct)
- It causes excessive vomiting.
Where is most of the hypoglycin found in ackee fruit?
Where is most of the hypoglycin found in ackee fruit?
- In the pulp
- In the skin
- In the stem
- In the seed (correct)
What role do amino acids play in higher animals?
What role do amino acids play in higher animals?
- They serve as building blocks for proteins and precursors for various biomolecules. (correct)
- They are only used for energy storage.
- They have no significant function in animal metabolism.
- They are primarily used as structural materials in bones.
What major fates do amino acids' carbon skeletons have when they are used as fuel?
What major fates do amino acids' carbon skeletons have when they are used as fuel?
How do vertebrates digest proteins for absorption?
How do vertebrates digest proteins for absorption?
What is the term used to refer to each unit of an amino acid sequence?
What is the term used to refer to each unit of an amino acid sequence?
How do amino acids serve as a source of energy when ingested in excess?
How do amino acids serve as a source of energy when ingested in excess?
What happens when brain cells lack glucose?
What happens when brain cells lack glucose?
What happens to a protein if the disulfide bridge linking the A-chain and B-chain of insulin is broken?
What happens to a protein if the disulfide bridge linking the A-chain and B-chain of insulin is broken?
Which amino acid is responsible for the formation of disulfide bonds in proteins?
Which amino acid is responsible for the formation of disulfide bonds in proteins?
What is the structural difference between cysteine and cystine?
What is the structural difference between cysteine and cystine?
Which amino acid is known for its polarity due to the amide group?
Which amino acid is known for its polarity due to the amide group?
Which amino acid functions as a hydrogen bond donor?
Which amino acid functions as a hydrogen bond donor?
Which amino acid is negatively charged and referred to as aspartate when charged?
Which amino acid is negatively charged and referred to as aspartate when charged?
How many hydrophilic residues typically occur on the exterior surface of proteins?
How many hydrophilic residues typically occur on the exterior surface of proteins?
What is the function of the CO group in proteins?
What is the function of the CO group in proteins?
What physiological symptoms do phenylketonurics experience?
What physiological symptoms do phenylketonurics experience?
How does phenylketonuria affect tyrosine metabolism?
How does phenylketonuria affect tyrosine metabolism?
What skin-related condition is commonly observed in phenylketonurics?
What skin-related condition is commonly observed in phenylketonurics?
Why do phenylketonurics have lighter skin and hair colour compared to their siblings?
Why do phenylketonurics have lighter skin and hair colour compared to their siblings?
What is the first step in the formation of melanin?
What is the first step in the formation of melanin?
What are the common CNS symptoms associated with phenylketonuria?
What are the common CNS symptoms associated with phenylketonuria?
What is the recommended therapy for phenylketonuria patients?
What is the recommended therapy for phenylketonuria patients?
Why is early diagnosis crucial for phenylketonuria?
Why is early diagnosis crucial for phenylketonuria?
What is the major biochemical abnormality associated with Parkinson's Disease?
What is the major biochemical abnormality associated with Parkinson's Disease?
Which neurotransmitter is primarily affected in Parkinson's Disease?
Which neurotransmitter is primarily affected in Parkinson's Disease?
What happens to the release of dopamine as the number of surviving cells decreases in Parkinson's Disease?
What happens to the release of dopamine as the number of surviving cells decreases in Parkinson's Disease?
Why is the administration of DOPA used in Parkinson's Disease treatment?
Why is the administration of DOPA used in Parkinson's Disease treatment?
What fate do ketogenic amino acids meet during degradation?
What fate do ketogenic amino acids meet during degradation?
What distinguishes glucogenic amino acids from ketogenic amino acids in terms of degradation?
What distinguishes glucogenic amino acids from ketogenic amino acids in terms of degradation?
What is the common fate of the carbon atoms from the degradation of amino acids?
What is the common fate of the carbon atoms from the degradation of amino acids?
What happens to dopamine levels when its concentration exceeds a certain threshold in Parkinson's Disease?
What happens to dopamine levels when its concentration exceeds a certain threshold in Parkinson's Disease?
What is the purpose of transamination?
What is the purpose of transamination?
Which enzyme is responsible for the formation of ammonia from glutamate?
Which enzyme is responsible for the formation of ammonia from glutamate?
What is the prosthetic group of all transaminases?
What is the prosthetic group of all transaminases?
Where does oxidative deamination take place in the cell?
Where does oxidative deamination take place in the cell?
What are the products of the reaction Glutamate + Oxaloacetate?
What are the products of the reaction Glutamate + Oxaloacetate?
Why is it essential to convert NH4+ to urea in the liver?
Why is it essential to convert NH4+ to urea in the liver?
Which amino acid reacts with alpha-ketoglutarate to form p-phenylpyruvate and glutamate?
Which amino acid reacts with alpha-ketoglutarate to form p-phenylpyruvate and glutamate?
What is the nitrogen acceptor in the transamination reaction?
What is the nitrogen acceptor in the transamination reaction?
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Study Notes
Amino Acid Metabolism
- Amino acids serve as building blocks of proteins and as precursors of many other important biomolecules such as hormones, purines, pyrimidines, porphyrins, and vitamins.
- They also serve as a source of energy, particularly when they are ingested in excess.
Digestion
- Proteins cannot enter epithelial cells, and must be digested into amino acids or di-or tripeptides before absorption can occur.
- Digestion involves several stages, including extraction of proteins from food, denaturation of proteins, and more.
Transamination
- Glutamate plays a crucial role in collecting amino groups from all over to form glutamate.
- Transamination reactions involve the transfer of an amino group from an amino acid to a keto acid, resulting in a new amino acid and a keto acid.
- Examples of transamination reactions include:
- Glutamate + Oxaloacetate → α-KG + Aspartate
- Ala + KG → Pyruvate + Glutamate
- Asp + KG → OAA + Glutamate
- Leu + KG → Ketoisocaproate + Glutamate
- Tyrosine + KG → p-phenylpyruvate + Glutamate
Oxidative Deamination
- Glutamate is converted to α-KG and ammonia through oxidative deamination, catalyzed by glutamate dehydrogenase.
- The enzyme responsible is GLUTAMATE DEHYDROGENASE, a mitochondrial enzyme.
- The reaction involves the transfer of a hydride ion, with NAD+/NADP+ serving as a co-factor.
Phenylketonuria (PKU)
- PKU is a genetic disorder characterized by the inability to metabolize phenylalanine.
- Symptoms include mental retardation, seizures, hyperactivity, and tremors.
- The condition is diagnosed by testing urine with FeCl3, which gives a green olive color in the presence of phenylpyruvate.
- Treatment involves a low-phenylalanine diet, which must be started at birth to avoid irreversible brain damage.
Parkinson's Disease
- Parkinson's disease is a neurodegenerative disorder characterized by the degeneration of cells in certain areas of the brain, leading to a deficiency of dopamine.
- Symptoms include tremors, which can be relieved by administering DOPA.
- The administration of DOPA is not a permanent cure, and the disease remains uncontrolled.
Fates of Carbon Atoms of Degraded Amino Acids
- The carbon skeletons of 20 amino acids are funneled into seven major metabolic intermediates, including pyruvate, acetyl-CoA, acetoacetyl-CoA, α-KG, succinyl-CoA, fumarate, and OAA.
- Amino acids can be classified into ketogenic or glucogenic based on their fate.
- Ketogenic amino acids are degraded into acetyl-CoA or acetoacetyl-CoA, while glucogenic amino acids are degraded into pyruvate, α-KG, succinyl-CoA, fumarate, or OAA.
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