Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            Biochemistry I
Amino acid and Protein metabolism
Dr Abed Alnaser Drbal 
14.09.2024
Metabolism of other amino acids
Fates of Carbon Skeletons
❖Glucogenic amino acids are 
degraded to pyruvate or TCA 
intermediate.
❖Ketogenic amino acids are 
degraded to acetoacetyl-CoA or 
acetyl-CoA.
❖Some amino acids are both.
Metabolism of other amino acids
❖Glycine (Gly, G)
➢It is the simplest amino acid, a non-essential glucogenic amino acid and can be synthesized in animal tissues.
➢It is optically inactive. Chemically it is “amino acetic acid”
➢Glycine is an important amino acid forms many biologically important compounds in the body and used in
synthesis of: 
1. Heme
2. Purines
3. Creatine
4. Glutathione
5.Serine
6. Collagen contains very high (about 30%) content of glycine.
❑Conjugation reactions: As a conjugating agent, glycine performs two important functions:
➢The bile acids-cholic acid and chenodeoxy cholic acid-are conjugated with glycine.
Cholic acid + Glycine → Glycocholic acid
➢Glycine is important for detoxification of benzoic acid (commonly used as a food preservative) to hippuric
acid.
Metabolism of other amino acids
❖Degradation of glycine:
➢Glycine undergoes oxidative deamination by glycine synthase to liberate NH3, CO2 and one carbon fragment as N5, 
N10-methyleneTHF. 
➢Glycine synthase is a multienzyme complex and requires PLP, NAD+ and THF for its activity. This reaction is
reversible.
➢Glycine can be oxidized by D-amino acid oxidase into glyoxylic acid, which is oxidized into oxalic acid.
Metabolism of other amino acids
❖Glycinuria:
➢This is a rare disorder due to a defective renal reabsorption of glycine.
➢Glycinuria is characterized by increased tendency for the formation of oxalate renal stones.
❖Primary hyperoxaluria:
➢This disorder is characterized by increased urinary oxalate resulting in oxalate stones due to a defect in glycine
transaminase coupled with impairment in glyoxalate oxidation to formate.
❖Serine
➢
It is a non-essential glycogenic amino acid.
➢
Serine is utilized for the synthesis of 1. Glycine. 2. cysteine. 3. Ethanolamine and choline. 4. Sphingomyelin and cephalins. 5. 
Sphingosine (Amino alcohol).
Metabolism of other amino acids
❖Threonine
➢It is an essential hydroxy amino acid.
➢It is glycogenic and does not participate in transamination reactions.
➢Threonine has 2 asymmetric carbon atoms.
❖Methionine
➢It is an essential glucogenic amino acid.
➢Methionine is activated to active methionine or S-adenosylmethionine (SAM), which acts as methyl
donor in transmethylation reactions.
❖Synthesis of epinephrine from norepinephrine.
Metabolism of other amino acids
❖Synthesis of creatine from guanido acetate.
❖Synthesis of choline from ethanolamine.
Metabolism of other amino acids
❖Synthesis of melatonin from N-acetylserotonine.
❖Synthesis of anserine from Carnosine.
❖Synthesis of N-methyl nicotinamide from nicotinamide
Metabolism of other amino acids
❖Glutamate
➢It is non-essential glycogenic amino acids.
➢It is involved in th

            Quiz: