Alcohol & Proteins (midterm) Flashcards
Alcohol is made from carbs by which reaction- oxidation or reduction?
reduction rxn
Alcohol is also known as….
ethanol or EtOH
How does alcohol enter the body?
simple diffusion
Does alcohol require a digestive enzyme?
no, alcohol will go anywhere where there is water
What are the 3 things that the rate of absorption and transport of alcohol depends on?
1) rate of stomach emptying
2) intake of certain drugs
3) type of alcohol consumed
T/F: alcohol conc. in females is more than in males
true, this is also why males don’t get drunk as easily
Alcohol will move through the body wherever there is water. What does alcohol damage first? And then overtime?
first damages the cell membranes and then liver cells damage, which then can lead to liver damage
Can alcohol be stored in the body?
NO
What has the first priority in metabolism? All other metabolism stops until this is metabolized
alcohol metabolism
Some ethanol is metabolized by the __________ cells, but the ___________ cells metabolize the majority of ethanol
stomach, liver
What does alcohol metabolism depend on?
-gender
-race
-size
-food consumption
-physical condition
-alcohol content
3 enzyme systems are capable of oxidizing/detoxifying ethanol. What are these 3 systems?
1) alcohol dehydrogenase (ADH)
2) microsomal ethanol oxidizing system (MEOS)
3) catalase
Which enzyme system metabolizes alcohol first? Where is it found?
alcohol dehydrogenase, which is found in the liver
The more you drink alcohol, the more your tolerance will build. Which enzyme system is responsible for this?
microsomal ethanol oxidizing system (MEOS)
Which enzyme system is a minor pathway for oxidizing/detoxifying ethanol?
catalase
Which enzyme system is the “low ethanol intake” pathway?
alcohol dehydrogenase pathway
Where is alcohol dehydrogenase found?
cytosol of liver cells
Does the alcohol dehydrogenase pathway yield energy?
yes, generates lots of NADH
Ethanol converts to acetaldehyde. NAD is required. What enzyme does this?
alcohol dehydrogenase 1 (ADH1)
note: this is literally converting one toxic molecule to another
Ethanol converts to acetaldehyde. NAD is required. This is done with ADH1. From here, acetaldehyde will convert to what? It uses another NAD, a CoA, and ADH2.
acetyl CoA (which will then go through krebs cycle and make ATP)
What does it mean if you have a strong ADH1 and ADH2?
your body will make acetyl CoA faster and this will also allow you to drink more than the average person
What does it mean if you have efficient ADH1 but not ADH2?
acetaldehyde will build up in the body (this is a toxin and is a known carcinogen)
when build up happens, your face will turn red from drinking and you may develop a cough
What happens when your body has inefficient ADH1 and ADH2?
alcohol cannot be metabolized properly through ADH pathway so it will directly go to MEOS system
Acetyl CoA is made in the ADH pathway. What is the fate of Acetyl CoA now?
-will be metabolized more like a fat than a carb
-so it will make carbon dioxide, water, and FAs
-it will NOT be converted to glucose!!!!!
Which enzyme system is the “high ethanol intake” pathway?
MEOS pathway
note: this pathway works for not only alcohol but also drugs and foreign substances
Which enzyme system generates a lot of ROS (free radicals) which in turn depletes NADPH (an antioxidant)?
potential test q
MEOS pathway
Which enzyme system requires ATP for it to metabolize/detoxify alcohol?
MEOS pathway
In the MEOS pathway, ethanol gets converted to acetaldehyde. What does it require besides ATP?
oxygen and NADPH
What is the byproduct of MEOS pathway?
Water! This is why you pee a lot when you drink alcohol
Where does the MEOS system occur in the body?
liver
The MEOS pathway is similar to ETC but uses what enzymes that are different from ETC?
P450 enzymes
The _______ pathway increases alcohol metabolism, thus, alcohol tolerance
MEOS
(which when someone builds a super high tolerance they can drug overdose)
MEOS pathway requires ATP. What is associated with ATP and alcohol abuse?
weight loss
What is an antioxidant enzyme we talked about in class?
catalase
If theres a decrease in catalase production (usually due to excessive alcohol), then this results in….
premature grey hairs
In the catalase pathway, ethanol gets converted to acetaldehyde. The catalase enzyme is used. What is required for catalase to work?
hydrogen peroxide
What is the byproduct of catalase pathway?
water! same as MEOS pathway, but MEOS pathway produces way more
What is the definition of moderate alcohol intake?
1 drink a day for men and less than a drink a day for women
-5 oz of wine
-12 oz of beer
-1.5 oz of liquor
-3 oz sherry
What are the benefits of moderate alcohol intake?
-social benefits
-relaxation
-increases serum HDL, thus lowering the risk of CVD in middle age and older adults
-alcohol inhibits delta 6 desaturase which is required for synthesizing eicosanoids
What is the leading cause of death?
alcohol abuse
What deficiencies would you have if you are an alcoholic?
several vitamin and mineral deficiencies
alcohol abuse combined with tobacco = risk for what cancer?
esophageal and oral cancer
Besides mineral and vitamin deficiencies, what other risks are there with alcohol abuse?
-CVD
-liver damage (fatty liver or liver cirrhosis)
-fetal damage
-obesity
-cancer
-osteoporosis
-brain damage
-impotence
-sleep disturbances
A build up of acetaldehyde is toxic to what cells?
hepatocytes (liver cells)
Does alcohol damage DNA?
yes
Why do alcoholics have increased risk for fatty liver disease?
they have increased synthesis of fat from accelerated acetyl CoA production
Are advanced stages of liver damage reversible or irreversible?
irreversible
When enlarged fat hepatic cells burst and die, scar tissue replaces normal cells and ________________ develops
liver cirrhosis
What are some complications of liver damage due to alcohol abuse?
-malnutrition
-portal hypertension
-ascites (fluid filled abdominal cavity)
-hyponatremia (decreased sodium in blood)
-hepatic encephalopathy (brain damage due to liver complications)
-fat malabsorption
-osteoporosis
What is ascites?
fluid filled abdominal cavity bc of HTN and blockages
Is fetal alcohol syndrome avoidable?
yes
What is fetal alcohol syndrome?
alcohol consumption deprives the fetus of oxygen and nutrients
Is there a safe level of drinking while pregnant?
NO, abstinence is best
What is the definition of binge drinking?
-4+ drinks in a row
-acute alcohol intoxication
What are the signs of alcohol poisoning?
-semiconsciousness or unconsciousness
-slow respiration (less than 8 breathes per min, or more than 8 seconds between breaths)
-cold, clammy, pale, or bluish skin
-a strong odor of alcohol
T/F: proteins are found in every cell and tissue
true
Proteins help build and repair tissues while carbs….
spare muscle tissue
Are proteins a good energy source?
NO
If theres excessive protein intake, AAs cannot be stored, so what happens to them?
they’re broken down to make fat
What is the natural form of AAs- L form or D form?
L form
What makes up an amino acid?
-alpha carbon (and chiral carbon for all AAs besides glycine)
-R group
-amino group
-H
-acid/carboxyl group
If you remove the amino group in an AA structure, what does that make?
an alpha keto acid
What are the 3 branched chain AAs (BCAAs)?
1) valine
2) leucine
3) isoleucine
all 3 are essential
What are the 3 aromatic AAs?
1) phenylalanine (essential)
2) tryptophan (essential)
3) tyrosine (conditionally essential, essential for PKU pts)
What is the largest AA?
tryptophan/ trp
Which AA is a precursor for niacin (vitamin B3)?
tryptophan/ trp
Which AA initiates protein synthesis?
methionine (start codon)
What are the 3 basic/positively charged (protonated) AAs?
1) lysine (essential)
2) arginine (nonessential)
3) histidine (essential)
What are the 2 acidic/ negatively charged (deprotonated) AAs?
1) aspartate (aspartic acid)
2) glutamate (glutamic acid)
both are nonessential
What are the “10” essential AAs?
-phenylalanine
-valine
-threonine
-tryptophan
-isoleucine
-methionine
-histidine (conditionally essential, essential during +N balance)
-arginine (CONDITIONALLY ESSENTIAL, essential for kids)
-leucine
-lysine
PVT TIM HALL
What is phenylketonuria (PKU)?
-phenylalanine is an essential AA, but for pts with PKU their phenylalanine intake needs to be controlled because their phenylalanine hydroxylase enzyme is either missing or lacking
-phenylalanine hydroxylase should convert phenylalanine to tyrosine but in this case it does not
-tyrosine is usually nonessential BUT for PKU pts it becomes essential
-newborns are screened via the Guthrie test- if hyperphenylalanemia is present then they will need to be on a low phenylalanine diet to prevent mental retardation and death
What bond links 2 AAs together?
peptide bond
Glutathione (GSH) is an important tripeptide. Why?
-it is made up of glycine, cysteine, and glutamate
-the cysteine in the middle has a thiol group, which makes this tripeptide an antioxidant
Which AAs can be synthesized by the body?
nonessential AAs
What is transamination?
Transfer of amino group from AA to an alpha keto acid
ALL aminotransferases use a coenzyme. What is it and what is it derived from?
Pyridoxal phosphate, which is derived from vit B6
What are the 3 aminotransferase pairs we should know?
1) alpha KG and glutamate
2) pyruvate and alanine
3) aspartate and OAA
If alanine donates NH2 to alpha KG what enzyme is used and what are the products?
Enzyme= glutamate pyruvate aminotransferase (GPT) OR alanine aminotransferase (ALT)
Products= pyruvate and glutamate
What vitamin is required with ALT, AST, GPT, or GOT?
Vit B6
If aspartate donates NH2 to alpha KG, what enzyme is used and what are the products?
Enzyme= glutamate OAA aminotransferase (GOT) or aspartate aminotransferase (AST)
Products= OAA and glutamate
High quality protein, also known as complete protein comes from where? Why are they condiered high quality?
-animal products
-contain all 9 essential AAs
What is low quality protein?
-most plants
-deficient or low in 1+ essential AAs
-high in soluble fiber and phytochemicals
-no cholesterol
-low in saturated fat
Grains, nuts and seeds are deficient in which 2 AAs?
isoleucine and lysine
Beans, lentils, and legumes are deficient in which 2 AAs?
methionine and tryptophan
What low quality proteins are the perfect combo to get in all the essential AAs?
-grains + legumes
-grains + veggies
-nuts/seeds + legumes
-nuts/seeds + veggies
note: peanuts are legumes not nuts
so a pb sammy on whole grain bread is good
or black beans with sesame seeds (weird examples, but this is what she had in notes)
What is the pH of gastric juice?
1.5-2.0
T/F: gastric juice is an antiseptic
true
Gastric juice denatures ___________ proteins (opens them up for enzyme activity)
globular
Gastric juice cleaves _____________ to make __________
pepsinogen, pepsin
Pepsinogen is secreted from what cells?
chief cells
CCK is secreted from what cells?
I cells in the duodenum
What activates trysinogen to make trypsin?
enterokinase
Trypsin cleaves….
-chymotrypsinogen to make chymotrypsin
-proelastase to make elastase
-procarboxypeptidase to carboxypeptidase
The SI produces aminopeptidase which is an….
exopeptidase
Proteolytic enzymes are usually ___________
zymogens
What are exopeptidases?
enzymes that cleave the end terminals
ex: carboxypeptidase and aminopeptidase
Carboxypeptidase cleaves the….
C terminal of an AA
Aminopeptidase cleaves the….
N terminal of the peptide chain
What are endopeptidases?
enzymes that cleave within the protein chain
ex: trypsin, chymotrypsin, pepsin
Trypsin cleaves the carboxyl end of what AAs?
Lys and Arg
Chymotrypsin cleaves the carboxyl end of what AAs?
Phe, Trp, and Tyr (aromatic AAs)
Pepsin cleaves the carboxyl end of what AAs?
Phe, Trp, and Tyr (aromatic AAs)
Protein digestion starts where?
in the stomach
HCI activates pepsinogen and makes pepsin. The proteins are denatured and will synthesize polypeptides, oligopeptides, and AAs. These peptides/AAs trigger intestinal endocrine cells in the duodenum to activate I cells to release CCK which will stimulate pancreatic acinar cells to secrete digestive enzymes. Small intestinal mucosal cells secrete ______________________ which activates trypsinogen. Trypsinogen will activate chymotrypsinogen, proelastase, procarboxypeptidase. This will result in mostly free AAs or some oligopeptides which will be absorbed via the carrier on the lumen. The oligopeptides are hydrolyzed into single AA within the mucosal cells. The free AAs enter the capillaries through portal circulation and each transporter is highly specific or a particular group of AAs, based on chemical structure
enteropeptidase (EP)
What is hartnup disease?
-disorder of tryptophan transport in the intestine and kidneys
-its a “pellagra-like” (niacin or tryptophan deficiency) metabolic disorder
-tryptophan can be converted into niacin, a precursor to nicotinamide, a necessary component of NAD
What is cystinuria?
-caused by the inability to reabsorb cysteine in the kidney
-under normal circumstances, the kidney allows certain AAs, including cysteine to be reabsorbed by a transporter protein into the blood from the filtered fluid that will become urine
-mutations in this transporter protein allow cysteine to become concentrated in the urine and kidneys
-as the levels of cysteine in the urine increases, crystals made of cysteine will form and cause kidney stones
-cystine crystals cause persistent kidney stones and reoccurrence of bladder infection
-cystine is the oxidized dimer form of cysteine, so when it gets really bad, cysteine converts to cystine
-if not appropriately treated then the disease will cause severe kidney damage and surrounding organs and then death
major nitrogen waste ends up where?
in urea and gets excreted (some will be converted to uric acid)
What makes uric acid?
purines and ammonia
What is nitrogen balance?
the normal condition in which the amount of nitrogen entering the body each day equals the amount excreted
What is negative nitrogen balance?
occurs when nitrogen loss exceeds nitrogen intake and is associated with the following:
-protein malnutrition (kwashiorkor- edema and low albumin levels)
-dietary deficiency of even one essential AA (body will break down muscles to find it if you don’t consume it)
-starvation (maramus)
-uncontrolled diabetes
-infections
What is positive nitrogen balance?
occurs when the amount of nitrogen intake exceeds the amount excreted and is associated with the following:
-muscle growth or children growing
-pregnancy
-recovery phase of injury or surgery
-recovery from negative nitrogen balance
T/F: alcohol can be oxidized by catalase
true
