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Session 1 BC- AA deg
BioChem- PA TOURO 2011 BIOCHEM amino acid degredation
Question | Answer |
---|---|
What is the cause of PKU | deficiency in phenylalanine hydroxylase (PAH) |
Why is PKU a problem | PHE is elevated in tissues, plasma and urine it gets converted into phenylketones. High PHE decreases brain levels of other aromatic AA in brain |
What are the symptoms of PKU | mental retardation, failure to walk or talk, seizures, tremor, and microcephaly |
How common is PKU allele in US and why is it not a problem in the womb | 1 in 50, mother clears the Phe in the fetus. Because of this testing cannot not be done right after birth but should be done at second feeding |
What is the treatment for PKU and how long should it continue | low protein, low PHE diet that has to start 7-10 days after birth to avoid mental retardation. must follow diet for life |
What is maple syrup urine disease | recessive disorder deficiency of branched-chain a-ketoacid dehydrogenase (BCAKD) Accumulation of Leu, Ile, and Val and their corresponding a-keto acids in blood causes toxic effect on the brain |
Symptoms of Maple syrup urine disease | vomiting, dehydration, severe metabolic acidosis with no treatment disease leads to mental retardation, physical disabilities, and death |
What are the types of maple syrup urine disease | Classic type- no BCAKD activity severe acidosis in first week of life. Intermediate type- 4-5% of normal enzyme activity can be treated with large doses of thiamine. |
What is the treatment of Maple syrup urine disease | giving Leu, Ile, and Val in low doses in diet. need to be tested within first 24 hours and start treatment to continue normal development |
What is Albinism | it is deficiency in melanin production can be autosomal dominant, recessive,or x linked. Complete albinism is from deficiency of tyrosinase activity |
What are the two types of melanine and their sub types | Eumelanin (most abundant)- Black and Brown Pheomelanin has a pink to red hue. |
What are mongolian spots | birthmark results from entrapment of melanocytes in the dermis. normally a blue, black or brown mark. |
What is Homocystinuria | autosomal recessive disease with high plasma and urine levels of Met and homocysteine. Homozygous patients can have mental retardation and arterial disease |
What is treatment for homocstinuria | Low methionine diet with supplementation with vit B12 and B6 and folate which can help metabolize Met. |
What is the major cause of death for people with homocystinuria | about 25% die of myocardial infarction before age 30 |
What is Alkaptonuria | black urine disease rare 1 in 1 million, they have high homogentisic acid, large joint arthritis, and black pigmentation of cartilage. Caused by deficiency in homogentisate oxidase |
What is the treatment of Alkaptonuria | no treatment late in life once you have the associated arthritis you just have to suffer. Can be prevented with nitisionone insectiside that inhibits homogentisic acid. |
What are nonesential amino acids (definition not list) | AA that can be synthesized by us |
What are essential amino acids | AA that can not be synthesized and we get them from the diet |
Why are AA acids broken down? | carbon skeletons give seven intermediate products used in sythesis of glucose and lipids. Production of energy by oxidizing them in the TCA cycle |
Which amino acids are strictly ketogeneic | Leucine, Lysine |
Which AA can be both keto-genic and glycogenic | Phenylalanine, Isoleucine, tyrosine, and Tryptophan. |
AA that yield pyruvate or the intermediates of TCA cycle are called? | Glycogenic or glucogenic the give rise to glucose or glycogen formation |
AAA acids that yield acetoacetate or its precursors (acetyl or acetoaacetyl-CoA) are called what type of AA | Ketogenic give rise to ketone bodies |
Homocystein can be converted into two AA name them and the cofactor needed for the conversion | Homocystein to Methionine needs Folate & Vit B12 Homocystein to Cystein needs Vit B6 |
What is the role of folic acid in AA metabolism | It is a source of one carbon unit along with methanol, formaldehyde, formic acid and carbonic acid |
What are the two carbon carriers in AA metabolism | Tetrahydrofolic acid and S-adenosylmethionine(SAM) |
What makes the active form of Folic Acid (THF) | Dihydrofolate reductase |
List the 9 essential amino acids | His, Iso, Leu, Lys, Met, Phe, Thr, Trp, Val |
Beans are a good source of which essential amino acds | Lysine and Thr |
Rice is a good source of which essential AA | Met |
What is Kwashiorkor | childhood malnutrition due to insufficient protein uptake |
How are the non essential AA made | Made from intermediates of metabolism |
Except Tyr, Phe, and Cys was is required for AA synthesis | Sulfur from Met |
Which nonessential AA is considered essential during childhood because the body cannot convert enough for growth | Arg |
What is transamination | Transfer of amino group to alpha keto acids. Ala, Asp, Glut. each has their own transferase ie ALT |
What is the only AA from glycolisis | Ser |
What are the consequences of defects in AA metabolism | mental retardation and developmental abnormalities. |
How are AA metabolism defects detected | Through screening of new borns generally 10 to 20 markers are tested for abnormalities |