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NBCE - Part 1 / Biochemistry - Irene Gold Review
Questions with complete & Updated Solutions
All amino acids are L-form except? - Answer ✔️ ✔️ -glycine
T/F - All amino acids are amphoteric? - Answer ✔️ ✔️ -T
What does amphoteric mean? - Answer ✔️ ✔️ -Can act as either an acid or a base
What are the essential amino acids? - 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? - Answer ✔️ ✔️ -True
What are the purely ketogenic amino acids? - Answer ✔️ ✔️ -Leucine and Lysine
What amino acid is the precursor for carnitine? - Answer ✔️ ✔️ -Lysine
What is the function of carnitine? - Answer ✔️ ✔️ -takes FA into mitochondria for beta-oxidation
What are the aromatic amino acids? - Answer ✔️ ✔️ -phenylalanine
tyrosine
tryptophan
What is unique about tryptophan? - Answer ✔️ ✔️ -It has an indole ring
What are the sulfur-containing amino acids? - Answer ✔️ ✔️ -cysteine, methionine, and cystine
2 cysteines linked together make what? - Answer ✔️ ✔️ -cysteine
What are the branched chain amino acids? - Answer ✔️ ✔️ -isoleucine, leucine and valine
Maple syrup urine disease is a defect in? - Answer ✔️ ✔️ -the bodies ability to breakdown branched chain amino acids
What are the acidic amino acids? - Answer ✔️ ✔️ -aspartate and glutamate
What does aspartame contain that makes it neurotoxic in excess? - Answer ✔️ ✔️ - aspartic acid (aspartate)
What are the basic amino acids? - Answer ✔️ ✔️ -histidine, lysine and arginine
T/F - basic amino acids have the smallest positive net charge at NORMAL pH of blood? - Answer ✔️ ✔️ -F - greatest positive net charge
What is nicotinamide derived from? - Answer ✔️ ✔️ -Tryptophan --> niacin --> nicotinamide
For every 10 kg of body wt, how many grams of protein does a person need? - Answer ✔️ ✔️ - 8 g
What is the isoelectric point? - Answer ✔️ ✔️ -pH when an amino acid has no net electrical charge (neutral)
What is a zwitter ion? - Answer ✔️ ✔️ -an amino acid at its isoelectric point
What is glutathione? - Answer ✔️ ✔️ -tripeptide of glycine + glutamate + cysteine
What is selenium?. - Answer ✔️ ✔️ -mineral for enzyme glutathione peroxidats
What is insulin? - 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? - Answer ✔️ ✔️ -insulin & glucagon
What are two examples of catecholamines that function in opposition? - Answer ✔️ ✔️ - epinephrine & norepinephrine
What are examples of steroids? - Answer ✔️ ✔️ -testosterone, cortison, estrogen, progesterone
What is the characteristic bond of a protein? - 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? - Answer ✔️ ✔️ -linear sequence of aa
What is the secondary structure of a protein? - Answer ✔️ ✔️ -alpha-helix & beta- pleated sheets
- held together by hydrogen bonds between atoms of polypeptide backbone
What are examples of secondary structures of proteins? - Answer ✔️ ✔️ -fibrous protein's collagen and silk; 2 dna strands together
What is a tertiary protein structures? - Answer ✔️ ✔️ -Folding of a single polypeptide chain in solution.
What are examples of tertiary protein structures? - Answer ✔️ ✔️ -- myoglobin
What is a quaternary protein structure? - Answer ✔️ ✔️ -Association of two or more polypeptide chains to make a functional protein
What is the classic example of a quaternary structure? - Answer ✔️ ✔️ -- hemoglobin
- hydrogen and disulfide bonds
What is an allosteric compound and an example? - 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? - Answer ✔️ ✔️ - disulfide bond
What is the Km of an enzymatic rxn? What is the relationship? - Answer ✔️ ✔️ -- a measure of the affinity that an enzyme has towards the substrate
- inverse relationship = the lower the Km, the higher the affinity
- FAD
- Oxidation/reduction dehydrogenase enzyme
- Cheilosis, angular stomatitis, magenta tongue
- destroyed by light
B3 - Answer ✔️ ✔️ -- niacin
- NAD, NADP, nicatinamide, adenine dinucleotide
- redox rxn
- Pellegra
- 4 D's: dementia, diarrhea, dermatitis, death
- tryptophan (T) --> niacin --> nicatinamide
B5 - Answer ✔️ ✔️ -- pantothenate
- structural component of coenzyme A (CoA)
- burning foot syndrome (parasthesias)
- heat labile
B6 - Answer ✔️ ✔️ -- pyridoxine
- transamination; ketoacid <-> amino acid
- amino acid metabolism
B7 - Answer ✔️ ✔️ -- biotin
- biocytin
- carboxylation (+CO2); eg acetyl-coA carboxylase (lipogenesis)
- avidin in egg whites depletes biotin
- intestinal bacterial make
B9 - Answer ✔️ ✔️ -- folic acid
- tetrahydrofolate
- one carbon transfers (methyl transfer)
- DNA & RNA synthesis
- megaloblastic anemia
- glossitis
- neural tube defects --> spina bifida
B12 - 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 - Answer ✔️ ✔️ -- ascorbic acid
- lipid antioxidant
- excess = diarrhea
- best source is wheat germ oil
Vit K - 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 - Answer ✔️ ✔️ -- glucose tolerance factor
- helps bind insulin to cell
- impaired glucose tolerance
Cobalt - Answer ✔️ ✔️ -- constituent of vitamin B 12
Magnesium - Answer ✔️ ✔️ -- binds to ATP
- muscle contraction/relax
- protein production
- many enzymes
- mg/ca ration 1:
- hyperexcitability
- muscle weakness
- sleepness
Iodine (I) - Answer ✔️ ✔️ -- thyroxine (T 4 )
- triiodothyronine (T3)
- stored as thyroglobulin
- children: cretinsim
- adults: goiter, myxedema
Iron (Fe) - Answer ✔️ ✔️ -- heme enzymes, hemoglobin, cytochromes
- transported transferrin
- stored ferritin
- Hypochromatic microcytic anemia
Selenium (Se) - Answer ✔️ ✔️ -- cofactor
- glutathione peroxidase
- antioxidant
Zinc ( Zn) - Answer ✔️ ✔️ -- cofactor
- carbon anhydrase
- immune system
- taste
what is the active form of vitamin D? - Answer ✔️ ✔️ -1,25 dihydroxycholecalciferol (vit D3)
What is the most active form of iron? - Answer ✔️ ✔️ -Fe 3 + = ferric
What is the most absorbable form of iron? - Answer ✔️ ✔️ -Fe 2 + = ferrous
What is the pathway of iron in the body? - Answer ✔️ ✔️ -Fe3+ (in food) --->(vit C) Fe2+ (absorbed in intestines) --> Fe 3+ (used in body)
What vitamins are considered antioxidants? - Answer ✔️ ✔️ -Vitamin A, C, E and Selenium
What do glutathione, lipoic acid and CoQ10 all have in common? - Answer ✔️ ✔️ - They are all antioxidants
What is the function of PTH? - Answer ✔️ ✔️ -increases serum calcium
What is the function of calcitonin? - Answer ✔️ ✔️ -decreases serum calcium
Monosaccharides are characterized into what two groups? - Answer ✔️ ✔️ - aldehydes or ketones
What carbon number is the aldehyde group always on? - Answer ✔️ ✔️ -carbon 1
What carbon number is ketone on in carbohydrate? - Answer ✔️ ✔️ -carbon 2
Glucose and galactose are what type of epimer? - Answer ✔️ ✔️ -C- 4
glucose and maltose are what type of epimer? - Answer ✔️ ✔️ -C- 2
Anomer - Answer ✔️ ✔️ -anomeric carbons are formed when sugars cyclize; either alpha or beta
sucrose is made up of... - Answer ✔️ ✔️ -glucose & fructose (alpha 1 , beta 2 )
lactose is made up of... - Answer ✔️ ✔️ -galactose + glucose (beta 1,4)
Maltose is made up of - Answer ✔️ ✔️ -glucose + glucose (alpha 1,4)
Isomaltose is made up of... - Answer ✔️ ✔️ -glucose + glucose (alpha 1,6)
cellobiose is made up of .... - Answer ✔️ ✔️ -glucose + glucose (beta 1,4)
What bond can lactase break? - Answer ✔️ ✔️ -beta 1,
What bond can amylase break - Answer ✔️ ✔️ -alpha 1 , 4 into maltose
What does amylopectin break into? - Answer ✔️ ✔️ -maltose and isomaltose
What does amylose break into? - Answer ✔️ ✔️ -just maltose
Glycogen contains what type of bonds? - Answer ✔️ ✔️ -alpha 1,4 and alpha 1,
amylose contains what type of bonds? - Answer ✔️ ✔️ -alpha 1,
amylopectin contains what type of bonds? - Answer ✔️ ✔️ -alpha 1,4 and alpha 1, 6
cellulose contains what type of bonds? - Answer ✔️ ✔️ -beta 1,4 (fiber)
What is the most common GAG? - Answer ✔️ ✔️ -hyaluronic acid & chondroitin sulfate
Where is hyaluronic acid found? - Answer ✔️ ✔️ -synovial fluid
Where is chondroitin sulfate found? - Answer ✔️ ✔️ -cartilage, tendons, ligaments
Ester bond? - Answer ✔️ ✔️ -acid + alcohol
What is the most saturated oil and therefore the least likely to become rancid? - Answer ✔️ ✔️ -coconut oil
What oil is primarily found in olive oil? - Answer ✔️ ✔️ -oleic acid (omega- 9 )
What are the saturated fats and how many carbons do they have? - 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? - 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? - Answer ✔️ ✔️ -- sphingolipids
Where is sphingomyelin found? - Answer ✔️ ✔️ -major lipid component in myelin
What happens when a person has a deficiency in sphingomyelinase? - Answer ✔️ ✔️ - Niemann-Pick disease
What is the most abundant sterol in humans? - Answer ✔️ ✔️ -cholesterol; derived from acetyl CoA
HMG-CoA reductase - Answer ✔️ ✔️ -- rate-limiting enzyme of cholesterol synthesis
- converts HMG-CoA to mevalonate
What is the rate-limiting enzyme in steroid biosynthesis? - Answer ✔️ ✔️ -- desmolase
- converts cholesterol --> pregnenolone
What function does fiber have in the elimination of cholesterol - Answer ✔️ ✔️ -fiber binds biles salts
What is the rate limiting enzyme of ketone body synthesis? - Answer ✔️ ✔️ -HMG- CoA synthase
Chylomicron - Answer ✔️ ✔️ -- produced & secreted from intestinal mucosal cells
- produced in response to dietary intake of fat
- carry triacylglycerides to peripheral tissues
VLDL - Answer ✔️ ✔️ -- synthesized and secreted from liver
- transports triacylglycerides to peripheral tissues from teh liver
LDL - Answer ✔️ ✔️ -- derived from VLDL
- transport cholesterol from the liver to peripheral tissues
- contains great amounts of cholesterol
HDL - Answer ✔️ ✔️ -- synthesized & secreted from the liver
- transports cholesterol from peripheral tissues back to the liver
What is the base pairing for DNA? RNA? - Answer ✔️ ✔️ -At The Golf Course
A-T
G-C
A-U
G-C
Phosphodiester bonds - Answer ✔️ ✔️ -- 3 prime carbon in one sugar w/ 5 prime carbon of another
Replication - Answer ✔️ ✔️ -- DNA --> DNA
- nucleus
- S phase
- 5 prime - > 3 prime
- antiparallel
- DNA polymerase
Transcription - 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 - Answer ✔️ ✔️ -- mRNA --> protein
- cytoplasm
- rough ER
- peptidyl transferase links 2 aa together
Protein synthesis - Answer ✔️ ✔️ -- ribosome reads mRNA 5 prime --> 3 prime
reverse transcription - Answer ✔️ ✔️ -- RNA back to DNA
Cori Cycle - 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 - Answer ✔️ ✔️ -- mitochondrial matrix
- pyruvate --> acetyl-CoA
- oxidative decarboxylation
- stimulated by insulin,
