Biochemistry Concepts and Amino Acids, Exams of Advanced Education

Download Biochemistry Concepts and Amino Acids and more Exams Advanced Education in PDF only on Docsity!

NBCE - Part 1 / Biochemistry - Irene

Gold Exam Review With 100% Correct

Answers 2023-

All amino acids are L-form except? - Correct Answer-glycine T/F - All amino acids are amphoteric? - Correct Answer-T What does amphoteric mean? - Correct Answer-Can act as either an acid or a base What are the essential amino acids? - Correct Answer-P = phenylalanine V = valine T = tryptophan T = threonine I = isoleucine M = methionine H = histidine A = arginine L = leucine L = lycine T/F - histidine is essential in a child but not an adult? - Correct Answer-True What are the purely ketogenic amino acids? - Correct Answer-Leucine and Lysine What amino acid is the precursor for carnitine? - Correct Answer-Lysine What is the function of carnitine? - Correct Answer-takes FA into mitochondria for beta- oxidation What are the aromatic amino acids? - Correct Answer-phenylalanine tyrosine tryptophan What is unique about tryptophan? - Correct Answer-It has an indole ring What are the sulfur-containing amino acids? - Correct Answer-cysteine, methionine, and cystine 2 cysteines linked together make what? - Correct Answer-cysteine What are the branched chain amino acids? - Correct Answer-isoleucine, leucine and valine

Maple syrup urine disease is a defect in? - Correct Answer-the bodies ability to breakdown branched chain amino acids What are the acidic amino acids? - Correct Answer-aspartate and glutamate What does aspartame contain that makes it neurotoxic in excess? - Correct Answer- aspartic acid (aspartate) What are the basic amino acids? - Correct Answer-histidine, lysine and arginine T/F - basic amino acids have the smallest positive net charge at NORMAL pH of blood?

• Correct Answer-F - greatest positive net charge Wheat is lacking in which aa? - Correct Answer-lysine Rice is lacking in which aa? - Correct Answer-lysine Legumes are lacking in which aa? - Correct Answer-tryptophan Maize is lacking in which aa's? - Correct Answer-lysine and tryptophan Pulses are lacking in what aa? - Correct Answer-Methionine (or cysteine) Eggs and chicken are lacking in what aa? - Correct Answer-none Phenylketonuria is a deficiency in which enzyme and limits conversion of which two amino acids? - Correct Answer-Phenylalanine hydroxylase; cannot convert phenylalanine to tyrosine Tyrosine is the precursor for what neurotransmitters? - Correct Answer-L-dopa --> dopamine --> norepinephrine --> epinephrine (catecholamines) Tyrosine is a precursor for what pigment? - Correct Answer-L-dopa --> melanin (skin pigmentation) Albinism is a problem with the conversion of what? - Correct Answer-L-dopa --> melanin What hormones can tyrosine be converted to? - Correct Answer-T3, T What is melatonin derived from? - Correct Answer-Tryptophan --> serotonin --> melatonin What is histamine derived from? - Correct Answer-Histidine

What is nicotinamide derived from? - Correct Answer-Tryptophan --> niacin --> nicotinamide For every 10 kg of body wt, how many grams of protein does a person need? - Correct Answer-8g What is the isoelectric point? - Correct Answer-pH when an amino acid has no net electrical charge (neutral) What is a zwitter ion? - Correct Answer-an amino acid at its isoelectric point What is glutathione? - Correct Answer-tripeptide of glycine + glutamate + cysteine What is selenium?. - Correct Answer-mineral for enzyme glutathione peroxidats What is insulin? - Correct Answer-2 polypeptide chains linked by disulfide bonds

• not part of animal cell membrane, but helps glucose enter the cell What are two examples of polypeptide hormones that function in opposition? - Correct Answer-insulin & glucagon What are two examples of catecholamines that function in opposition? - Correct Answer-epinephrine & norepinephrine What are examples of steroids? - Correct Answer-testosterone, cortison, estrogen, progesterone What is the characteristic bond of a protein? - Correct Answer-peptide bond - type of amide bond that is specific for proteins (peptide bond aka C=N or carboxyl-amino bon What is the primary protein structure? - Correct Answer-linear sequence of aa What is the secondary structure of a protein? - Correct Answer-alpha-helix & beta- pleated sheets -held together by hydrogen bonds between atoms of polypeptide backbone What are examples of secondary structures of proteins? - Correct Answer-fibrous protein's collagen and silk; 2 dna strands together What is a tertiary protein structures? - Correct Answer-Folding of a single polypeptide chain in solution. What are examples of tertiary protein structures? - Correct Answer-- myoglobin
• disulfide bonds

What is a quaternary protein structure? - Correct Answer-Association of two or more polypeptide chains to make a functional protein What is the classic example of a quaternary structure? - Correct Answer-- hemoglobin

• hydrogen and disulfide bonds What is an allosteric compound and an example? - Correct Answer-a compound that changes conformational shape
• hemoglobin will change when oxygen binds to it What type of bond connects the light and heavy chains of an antibody? - Correct Answer-disulfide bond What is the Km of an enzymatic rxn? What is the relationship? - Correct Answer-- a measure of the affinity that an enzyme has towards the substrate
• inverse relationship = the lower the Km, the higher the affinity What is Vmax of an enzyme? How is it related to Km? - Correct Answer-- max velocity of an enzyme
• Km = 1/2Vmax What are the 3 main factors that affect the rxn velocity of an enzyme? - Correct Answer-

1. Substrate concentration
2. Temperature
3. pH What is Gibb's free energy? - Correct Answer-measure of the amount of energy available to determine if a reaction is energistically feasible If delta G is (+), is the rxn spontaneous? (-)? - Correct Answer-Spontaneous if delta G is negative B1 - Correct Answer-- thiamine

• TPP (thiamine pyrophosphate is active form)
• decarboxylation
• wet beri-beri = cardiovascular disease
• dry beri- beri = pns, wernicke-korsakoff syndrome
• numbness of legs (CVD) wet
• psychosis w/dementia (dry) What causes Wernicke-Korsakoff syndrome? - Correct Answer-B1 deficiency B2 - Correct Answer-- riboflavin
• FAD
• Oxidation/reduction dehydrogenase enzyme
• Cheilosis, angular stomatitis, magenta tongue

• destroyed by light B3 - Correct Answer-- niacin
• NAD, NADP, nicatinamide, adenine dinucleotide
• redox rxn
• Pellegra
• 4 D's: dementia, diarrhea, dermatitis, death
• tryptophan (T) --> niacin --> nicatinamide B5 - Correct Answer-- pantothenate
• structural component of coenzyme A (CoA)
• burning foot syndrome (parasthesias)
• heat labile B6 - Correct Answer-- pyridoxine
• pyridoxal-5-phosphate

1. transamination; ketoacid <-> amino acid
2. amino acid metabolism

• made by flora B7 - Correct Answer-- biotin
• biocytin
• carboxylation (+CO2); eg acetyl-coA carboxylase (lipogenesis)
• avidin in egg whites depletes biotin
• intestinal bacterial make B9 - Correct Answer-- folic acid
• tetrahydrofolate
• one carbon transfers (methyl transfer)
• DNA & RNA synthesis
• megaloblastic anemia
• glossitis
• neural tube defects --> spina bifida B12 - Correct Answer-- cobalamin
• methylcobalamin
• homocysteine remethylation
• pernicious anemia from decreased intrinsic factor
• PLS: posterior lateral sclerosis AKA combined systems disease
• B12 deficiency from any other cause is megaloblastic anemia (eg vegetarians)
• contains cobalt
• mainly in animal products Vit C - Correct Answer-- ascorbic acid
• hydroxylation of proline and lysine in collagen
• enhances iron absorption

• scurvy
• proline --> hydroxyproline
• Fe3+ --> Fe2+
• destroyed by heat
• one of the highest sources is brussels sprouts Vit A - Correct Answer-- retinal
• retinoic acid = most active form
• vision, growth
• night blindness = "nyctolopia"
• neratomalacia = degeneration of the cornea
• xerophthalmia = dry eyes
• vit for immune system Vit D - Correct Answer-- 1,25 - dihydroxycholecalciferol
• calcium and phosphate metabolism
• rickets in young
• osteomalacia in adults
• body can make Vit E - Correct Answer-- alpha-tocopherol
• lipid antioxidant
• excess = diarrhea
• best source is wheat germ oil Vit K - Correct Answer-- hydroquinoine
• menadione
• best source = green leafy veg
• blood clotting
• precursor for conenzyme Q
• def = clotting time
• converts prothrombin to thrombin
• made by fora Chromium - Correct Answer-- glucose tolerance factor
• helps bind insulin to cell
• impaired glucose tolerance Cobalt - Correct Answer-- constituent of vitamin B
• pernicious anemia Magnesium - Correct Answer-- binds to ATP
• muscle contraction/relax
• protein production
• many enzymes
• mg/ca ration 1:

• hyperexcitability
• muscle weakness
• sleepness Iodine (I) - Correct Answer-- thyroxine (T4)
• triiodothyronine (T3)
• stored as thyroglobulin
• children: cretinsim
• adults: goiter, myxedema Iron (Fe) - Correct Answer-- heme enzymes, hemoglobin, cytochromes
• transported transferrin
• stored ferritin
• Hypochromatic microcytic anemia Selenium (Se) - Correct Answer-- cofactor
• glutathione peroxidase
• antioxidant Zinc ( Zn) - Correct Answer-- cofactor
• carbon anhydrase
• immune system
• taste
• wound healing
• prostate
• impaired wound healing Flouride (F) - Correct Answer-- increased teeth hardness
• deficiency: dental caries
• excess: hyperlfuorosis Methionine Synthase is activated by what cofactors? - Correct Answer-B9 and B methionine --> homocysteine by myelination

• B12 gives methyl group to methionine
• B9 gives methyl group to B What does a B12 deficiency cause? - Correct Answer-anemia How does pernicious anemia occur? - Correct Answer-low intrinsic factor; megaloblastic anemia What happens if you are deficient in B-vitamins during remethylation cycle? - Correct Answer-you have a methylation deficiency What are the steps for vitamin D synthesis? - Correct Answer-7-dehydrocholesterol -->

(UV light) cholecalciferol --> (liver) 25-hydroxycholecalciferol --> (in kidney, 1-alpha- hydroxylase is rate limiting enzyme) 1,25 dihydroxycholecalciferol (vit D3) ACTIVE FORM what is the active form of vitamin D? - Correct Answer-1,25 dihydroxycholecalciferol (vit D3) What is the most active form of iron? - Correct Answer-Fe3+ = ferric What is the most absorbable form of iron? - Correct Answer-Fe2+ = ferrous What is the pathway of iron in the body? - Correct Answer-Fe3+ (in food) --->(vit C) Fe2+ (absorbed in intestines) --> Fe 3+ (used in body) What vitamins are considered antioxidants? - Correct Answer-Vitamin A, C, E and Selenium What do glutathione, lipoic acid and CoQ10 all have in common? - Correct Answer- They are all antioxidants What is the function of PTH? - Correct Answer-increases serum calcium What is the function of calcitonin? - Correct Answer-decreases serum calcium Monosaccharides are characterized into what two groups? - Correct Answer-aldehydes or ketones What carbon number is the aldehyde group always on? - Correct Answer-carbon 1 What carbon number is ketone on in carbohydrate? - Correct Answer-carbon 2 Glucose and galactose are what type of epimer? - Correct Answer-C- glucose and maltose are what type of epimer? - Correct Answer-C- Anomer - Correct Answer-anomeric carbons are formed when sugars cyclize; either alpha or beta sucrose is made up of... - Correct Answer-glucose & fructose (alpha 1, beta2) lactose is made up of... - Correct Answer-galactose + glucose (beta 1,4) Maltose is made up of - Correct Answer-glucose + glucose (alpha 1,4) Isomaltose is made up of... - Correct Answer-glucose + glucose (alpha 1,6)

cellobiose is made up of .... - Correct Answer-glucose + glucose (beta 1,4) What bond can lactase break? - Correct Answer-beta 1, What bond can amylase break - Correct Answer-alpha 1, 4 into maltose What does amylopectin break into? - Correct Answer-maltose and isomaltose What does amylose break into? - Correct Answer-just maltose Glycogen contains what type of bonds? - Correct Answer-alpha 1,4 and alpha 1, amylose contains what type of bonds? - Correct Answer-alpha 1, amylopectin contains what type of bonds? - Correct Answer-alpha 1,4 and alpha 1, cellulose contains what type of bonds? - Correct Answer-beta 1,4 (fiber) What is the most common GAG? - Correct Answer-hyaluronic acid & chondroitin sulfate Where is hyaluronic acid found? - Correct Answer-synovial fluid Where is chondroitin sulfate found? - Correct Answer-cartilage, tendons, ligaments Ester bond? - Correct Answer-acid + alcohol What is the most predominant form of fat/lipids in the body? - Correct Answer- Triacylglycerols Where does glycerol come from? - Correct Answer-glucose What do unsaturated fatty acids contain that decrease the melting temp? - Correct Answer-double bonds naturally occurring double bonds exist in what form? - Correct Answer-cis-conformation What is the purpose of hydrogenation? - Correct Answer-- raise melting pt

• decrease freezing pt
• increase shelf life
• makes trans fats oxidation - Correct Answer-loss of e- or hydrogen reduction - Correct Answer-gain of e- or hydrogen

When you go from unsaturated fat to saturated fat, is this oxidation or reduction? - Correct Answer-oxidation - you have fewer hydrogen What are the essential fatty acids? - Correct Answer-- linoleic acid

• linolenic acid
• arachidonic acid arachidonic acid is a precursor for? - Correct Answer-prostaglandins What is the most saturated oil and therefore the least likely to become rancid? - Correct Answer-coconut oil What oil is primarily found in olive oil? - Correct Answer-oleic acid (omega-9) What are the saturated fats and how many carbons do they have? - Correct Answer- lauric acid - 12 myristic acid - 14 palmitic - 16 stearic - 18 What are the unsaturated fats? How many carbons do they have? How many double bonds? - Correct Answer-Oleic Acid; 18; 1 C=C linoleic; 18; 2 C=C Linolenic ( alpha and gamma); 18; 3 C=C Arachidonic; 20 4 C=C What are the 2 main classes of nonglycerol lipids? - Correct Answer-- sphingolipids
• steroids Where is sphingomyelin found? - Correct Answer-major lipid component in myelin What happens when a person has a deficiency in sphingomyelinase? - Correct Answer- Niemann-Pick disease What is the most abundant sterol in humans? - Correct Answer-cholesterol; derived from acetyl CoA HMG-CoA reductase - Correct Answer-- rate-limiting enzyme of cholesterol synthesis
• converts HMG-CoA to mevalonate What is the rate-limiting enzyme in steroid biosynthesis? - Correct Answer--desmolase
• converts cholesterol --> pregnenolone What function does fiber have in the elimination of cholesterol - Correct Answer-fiber binds biles salts

What is the rate limiting enzyme of ketone body synthesis? - Correct Answer-HMG-CoA synthase Chylomicron - Correct Answer-- produced & secreted from intestinal mucosal cells

• produced in response to dietary intake of fat
• carry triacylglycerides to peripheral tissues VLDL - Correct Answer-- synthesized and secreted from liver
• transports triacylglycerides to peripheral tissues from teh liver LDL - Correct Answer-- derived from VLDL
• transport cholesterol from the liver to peripheral tissues
• contains great amounts of cholesterol HDL - Correct Answer-- synthesized & secreted from the liver
• transports cholesterol from peripheral tissues back to the liver Lipoprotein lipase - Correct Answer-required for the uptake of triglycerides/fatty acids that are carried by VLDL and chylomicrons What ratio contributes to the density of a lipoprotein? - Correct Answer-Protein/TAG What is the order of most dense to least dense lipoproteins? - Correct Answer-HDL -> LDL -> IDL -> VLDL -> chylomicrons The formation of deoxyribose from ribose is what type of rxn? - Correct Answer- reduction b/c you gained a hydrogen Purines? - Correct Answer-Pure As Gold Adenine & Guanine Purine nitrogen is derived from 3 aa - Correct Answer-- aspartate
• glycine
• glutamine What are the intermedates in purine metabolism? - Correct Answer-hypozanthine & xanthine
• leads to uric acid What are the pyrimidines? - Correct Answer-Thymine (DNA only) Uracil (RNA only) cytosine What is the chief component of chromatin? - Correct Answer-Histones - spools for DNA to wind

What is the base pairing for DNA? RNA? - Correct Answer-At The Golf Course A-T G-C A-U G-C Phosphodiester bonds - Correct Answer-- 3 prime carbon in one sugar w/ 5 prime carbon of another

• covalent bonds Replication - Correct Answer-- DNA --> DNA
• nucleus
• S phase
• 5 prime -> 3 prime
• antiparallel
• DNA polymerase Transcription - Correct Answer-- DNA --> mRNA
• 5 prime -> 3 prime
• every 3 bases = codon
• codon codes 1 aa
• RNA Polymerase
• 1st aa always codes methionine
• START AUG, GUG
• STOP: UAA, UGA, UAG Translation - Correct Answer-- mRNA --> protein
• cytoplasm
• rough ER
• peptidyl transferase links 2 aa together Protein synthesis - Correct Answer-- ribosome reads mRNA 5 prime --> 3 prime
• N term to C term

reverse transcription - Correct Answer-- RNA back to DNA Cori Cycle - Correct Answer-- anaerobic

• muscle & liver
• glucose in muscle converted to 2 molecules of lactate
• lactate to liver
• lactate converted to glucose in liver Pyruvate dehyrogenase complex - Correct Answer-- mitochondrial matrix
• pyruvate --> acetyl-CoA

• oxidative decarboxylation
• stimulated by insulin,
• inhibited by glucagon What are the coenzymes in pyruvate dehydrogenase complex? - Correct Answer-- NAD+ (B3)
• FAD+ (B2)
• Thiamine pyrophosphate (B1)
• lipoic acid
• CoA (B5) What are the regulatory enzymes in krebs> - Correct Answer-- citrate synthase
• isocitrate dehyrogenase
• alpha-ketoglutarate dehydrogenase complex per turn of krebs (1 acetyl-CoA) how many ATP do you get? per molecule of glucose? - Correct Answer-12; 24 How many NADH are produced in krebs and therefore how many more ATP? - Correct Answer-3 NADH = 9 ATP via ETC How many FADH2 are produced in krebs and therefore how many more ATP? - Correct Answer-1 FADH2 = 2 ATP (via ETC) How many GTP are used in krebs and how much ATP does it generate? - Correct Answer-1 GTP = 1 ATP (substrate level phosphorylation) ETC - Correct Answer-- each NADH results in 3 ATP
• each FADH2 results in 2 ATP
• O2 is ultimate electron acceptor
• CoQ is component Chemiosmotic hypothesis - Correct Answer-couples the ETC to the synthesis of ATP CoQ10 - Correct Answer-- similar in structure to what vitamin Vitamin K
• structure based on cholesterol
• delivers O2 to ETC
• activates complex I, II, III
• naturally produced in liver Gluconeogenesis - Correct Answer-- cytosol
• stim by glucagon and cortisol
• inhibited by insulin What are the primary precursors for gluconeogenesis? - Correct Answer-1. glycerol

2. lactate

3. amino acids pyruvate carboxylase - Correct Answer-pyruvate + CO2 + ATP --> Oxaloacetate + ADP *** carboxylation rxn, thus biotin is coenzyme

• mitochondria PEP Carboxykinase - Correct Answer-oxaloacetate + GTP --> PEP + GDP + CO ***both pyruvate carboxylase and PEP carboxyykinase are needed to bypass pyruvate kinase in glycolyss Fructose- 1,6-bisphosphatase - Correct Answer-fructose 1,6 bisphosphate --> fructose- 6-phosphate + Pi *** this enzyme bypasses PFK in glycolysis Glucose-6-phosphatase - Correct Answer-glucose-6-phosphate --> glucose + Pi *** present in liver, not muscle *** allows liver to generate free glucose from glycogen breakdown and gluconeogenesis *** glucose-6-phosphatase bypasses glucokinase in glycolysis What is the regulatory enzyme for glycogen synthesis? - Correct Answer-- glycogen synthase What is the hormone regulation for glycogen synthesis? - Correct Answer-- stimulated by insulin
• inhibited by glucagon What is the major intermediate for glycogen metabolism? - Correct Answer-UDP- glucose What is the major regulatory enzyme for glycogen degradation? - Correct Answer-- glycogen phosphorylase
• glycogen + Pi --> glucose-1-P + glycogen (n-1) What is the hormonal regulation for glycogen degradation? - Correct Answer-- inhibited by insulin
• stimulated by glucagon & epinephrine What are the aka's for HMP shunt? - Correct Answer-- pentose phosphate pathway
• phosphogluconate pathway HMP shunt? - Correct Answer-- cytosol
• regulatory enzyme: glucose-6-phosphate dehydrogenase What are the fxn's of HMP shunt? - Correct Answer-1. production of NADPH for both fatty acid synthesis and steroid hormone synthesis

2. production of ribose-5-phosphate for nucleotide synthesis

*** no net gain or loss of ATP Location of lipogenesis - Correct Answer-cytosol regulatory enzyme in lipogenesis? - Correct Answer-Acetyl CoA carboxylase Acetyl CoA + CO2 + ATP --> malonyl-CoA + ADP What hormones regulate lipogenesis? - Correct Answer-- stimulate by insulin

• inhibited by glucagon Coenzymes for lipogenesis? - Correct Answer-- NADPH from HMP SHNT
• fatty acid synthesis is a reductive process Acetyl CoA is transported from the mitochondria to cytosol as what? - Correct Answer- citrate Beta-oxidation - Correct Answer-- lypolysis
• mitochondria Regulatory enzymes of beta-oxidation? - Correct Answer-- hormone sensitive lipase
• cleaves fatty acids off triacylgycerides that are stored in the adipose tissue Hormonal regulation for beta-oxidation? - Correct Answer-- stimulated by epinephrine
• inhibited by insulin How does carnitine function in beta-oxidation - Correct Answer-transports fatty acids from the cytosol into the mitochondria What is the precursor amino acid for carnitine - Correct Answer-lysine Where does the Urea cycle occur? - Correct Answer-cytosol and mitochondria What amino acid is the nitrogen donor in the urea cycle? - Correct Answer-glutamate What is the rate-limiting enzyme in the Urea cycle? - Correct Answer-- carbamoyl phosphate synthase
• present in mitochondria
• catalyzes: CO2 + NH3 + + 2ATP --> carbamoyl phosphate Important intermediates of Urea cycle? - Correct Answer-ARCO ARginine Citrulline Ornithine