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Nutiriton Principles 1 Exam 1
Bastyr Advanced Nutrition Principles 1 Exam 1
76
Biochemistry
Undergraduate 4
10/20/2011

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Term
What form of cysteine would you administer to someone with liver failure to help them increase glutathione levels?
Definition
N-acetyl Cysteine
Term
Which glucose transporter is sensitive to insulin?
Definition
GLUT4
Term
What is the equation for Glycemic Load?
Definition
GI/100 x net carbs
Term
5. Why is the effect of consuming 50g of carbohydrate as starch (white bread) or glucose on blood glucose concentrations basically the same?
Definition
White bread has no fiber and nothing to slow gastric emptying, so it gets absorbed just as fast as glucose does.
Term
Protein digestion begins in the stomach as a result of the secretion of two molecules; what are they, what cells secrete them, and how do they participate in protein digestion?
Definition
Parietal cells secrete HCL - denatures proteins
Chief cells secrete Pepsinogen - endopeptidase cleaves proteins
Term
If one wanted to increase circulating SAM levels, what should they supplement with – methionine or SAM – and why?
Definition
SAM - because Methionine is used for repairing proteins within cells and is in high demand by other cells. It would be used before it could turn into SAM.
Term
Describe the digestion and absorption of dietary carbohydrates.
Definition
Salivary Amylase (breaks small amount of alpha-1-4 linkages). Pancreatic Amylase then further breaks them down. Brush boarder enzymes maltase, sucrase and latase break down disaccharides into monosaccharides. Glucose and Galactose get absorbed by the enterocytes via NA dependent active transport. Fructose goes through GLUT5.
Term
Name two molecules for which cholesterol is a precursor.
Definition
Vitamin D and Bile Salts.
Term
What is trehalose?
Definition
A disaccharide of 1-1 glucose linkage
Term
What do non-digestible oligosaccharides look like?
Definition
Sucrose + x (fructose, galactose, etc.)
Term
Differentiate between starch (amylose & amylopectin) and glycogen in terms of structure.
Definition
Amylose is simple 1-4 a linkage w/ no branching
Amylopectin involves branches every 25-30 glucose molecules
Glycogen involves branches roughly every 10 glucose molecules
Term
What differentiates cellulose from hemicellulose?
Definition
The average length of the molecule

Cellulose ~ 1000 units, is insoluble
Hemicellulose ~ 150 - 200 units, can be soluble or insoluble depending on the molecule
Term
What is a lignin?
Definition
A polysaccharide with phenol subunits
Term
True or false, gums are soluble and fermentable?
Definition
True
Term
What are the functions of the GI tract? (6)
Definition
Motility, Secretion, Digestion, Absorption, Elimination, Nutrient Absorption
Term
What transporter is used for both glucose and galactose in enterocytes?
Definition
SGLT1
Term
Where are glut2 transporters found and what specific function do they have?
Definition
They transfer glucose from enterocytes into the blood
Term
Where are glut5 transporters found and what are they responsible for?
Definition
In the intestines; fructose absorption
Term
What are the approximate lengths of the portions of the small intestine?
Definition
Duodenum ~10” to Jejunum 4-8’ to Ileum 5-10’
Term
Roles of the large intestine (5)
Definition
Capacity to absorb water, sodium, potassium, short-chain fatty acids, vitamin K production
Term
Health benefits of non-starch polysaccharides (6)
Definition
•Delayed gastric emptying of foods from stomach
•Decreased nutrient diffusion rate
•Increased fecal bulk (workout for intestines—helps to prevent diverticulosis)
•Increased substrate for gut bacteria
•Increased fecal bile acid excretion
•Decreased absorption of lipids
Term
What glycolysis step does excess fructose bypass when in abundance/excess?
Definition
Fructose bypasses PFK step
Term
Why are blood levels of galactose and fructose independent of absorption?
Definition
The liver removes galactose and fructose to keep them from going into circulation, and converts them into glucose byproducts that can be used by the liver
Term
Where are glut 2, 4, and 5 located?
Definition
GLUT2: Kidney, Pancreatic B-cell, serosal surface of intestinal mucosa cells, liver

GLUT4: Brown & White Adipose Tissue, Skeletal Muscle, Heart Muscle (muscle & fat)

GLUT5: Intestinal epithelium, spermatozoa, kidney
Term
Why are protease enzymes secreted as zymogens that need to be cleaved in order to become active?
Definition
So they don't degrade the proteins found in our bodies, on our cells.
Term
Amino acid score
Definition
= indispensable amino acid content in test food (mg/g protein) / content of same amino acid in reference protein (mg/g)
Term
Define Glycemic Index
Definition
A classification system that quantifies the impact of a dietary carbohydrate on the elevation of blood glucose levels relative to a reference food. Reflects ease of absorption.
Term
Carbohydrate and Fiber Recommended Intake Levels of Adults
Definition
o 130 g/d for adults

Fiber:
o 25 g/d for women
o 38 g/d for men
Term
What are five consequences of a low-carb diet?
Definition
Potential nutritional deficiencies
Bone mineral loss
Hypercholestemia
Low glycogen stores
ketosis
Term
What is the minimum Carbohydrate g/day recommendation based on?
Definition
130 g/day is the average minimum to avoid ketosis
Term
What are the 5 protein classifications?
Definition
• Enzymes
• Hormones
• Structural proteins
• Immunoproteins
• Transport
Term
What occurs in the stomach regarding protein digestion (3)?
Definition
HCl - parietal cells, denatures proteins

Pepsinogen - chief cells, cleavage to form pepsin activated by HCl

Pepsin- endopeptidase, non-specific, pH<3.5 (cleaves NOT at the ends) results in AA's
Term
What cofactor do carboxypeptidases require, and where do they cleave?
Definition
Require Zn

Are exopeptidases
Term
What protease enzymes do we need to know, and their sites of activity (6)
Definition
Pepsin stomach

Trypsin intestine

Chymotrypsin intestine

carboxypeptidase intestine

Elastase intestine

Collagenase
Term
3 general rules regarding AA rate of absorption
Definition
BCAA > smaller AA
Neutral AA > basic or acidic AA
EAAs > dispensible AAs
Term
What four AA's are used by enterocytes for a variety of processes (4) and what are those processes?
Definition
Glutamine, arginine, glutamate, and aspartate

used by enterocytes for energy, protein synthesis, glutathione synthesis, amino acid synthesis
Term
Define Essential Nutrient
Definition
A nutrient that the body cannot create and needs to consume
Term
What is the RDA for protein? What is the EAR for protein?
Definition
EAR = 0.66g protein/kg/d
RDA = 0.8 g/kg/d
Term
Define Protein Quality
Definition
The ability of a given amount of a particular protein to meet the body’s amino acid requirements
Term
What is complementarity or mutual supplementation for protein?
Definition
– Consuming certain protein containing foods together so that their separate amino acid limitations are eliminated
Term
What are the four sulfur containing -thiols?
Definition
• Methionine
o Essential amino acid as sulfide (-S-CH3)

• S-adenosylmethionine
o Methyl group donor

• Cysteine
o Carbon skeleton from methionine
o Considered conditionally essential

• Glutathione
o Tripeptide antioxidant
Term
Practice Drawing Methylation Diagram from p. 3 on outline 4
Definition
-

SAM is a methyl donor, needed for synthesis of many molecules/compounds including creatine, epinephrine, carnitine, phospholipids, choline, DNA, and RNA

After methylation reactions are complete, product is S-adenosyl homocysteine which is hydrolyzed to homocysteine

Remethylation – homocysteine to methionine (methionine synthase or betaine Hcy-methyltransferase)

Transsulfuration – homocysteine to cysteine
Term
Name some of the things SAM is required for (6)
Definition
creatine, epinephrine, carnitine, phospholipids, choline, DNA & RNA
Term
What three ways/locations can transulfuration occur?
Definition
Enterocytes and pancreatic cells can transulfurate

Alternate route using Betaine occurs in Liver
Term
What four functions does glutathione have?
Definition
Antioxidant – independent antioxidant effects; serves as a substrate for an antioxidant enzyme; and can regenerate other antioxidants (vit c)


Detoxification – GSH is a substrate for glutathione-S-transferases. These enzymes form GSH conjugates to detoxify and increase the solubility of many endogenous and xenobiotic compounds including estrogen, prostaglandins, heavy metals, some drugs and pesticides.

Other function – transport of amino acids via the γ-glutamyl transpeptidases, and is involved in leukotriene and melanin synthesis.

Sulfur storage.
Term
Three conditions where glutathione becomes conditionally essential
Definition
Requirement increases under conditions of oxidative stress

Synthesis increased with inflammation, ionizing radiation, heavy metals

Synthesis decreased with low protein diets
Term
Why would you not want to supplement in cysteine?
Definition
Cysteine is oxidized to insoluble disulfide form in stomach
Term
Name 4 uses for N-acetyl cysteine
Definition
Used to treat acetaminophen toxicity

Other uses – bronchitis, heart disease, heavy metal poisoning
Term
Why is cysteine considered conditionally essential? When (life stage) might it be conditionally essential?
Definition
Hepatic dysfunction or cirrhosis

Total parenteral nutrition

Premature infants

Growth Spurts?
Term
If you consumed a diet low in methionine but high in cysteine, what would happen?
Definition
less transsulfuration to cysteine
Term
What does Cystathionine B-synthase do?
Definition
Homocysteine --B6--> Cystathionine
Term
What are the fat digesting enzymes secreted by the mouth? What enzymes are secreted by the stomach?
Definition
Lingual lipase - secreted in mouth activated in low pH of the stomach

Gastric lipase - secreted by the chief cells of the stomach and active in low pH of stomach
Term
Recreate Lipoprotein Picture from outline 5 page 4
Definition
-
Term
What fat enzymes are secreted by the pancreas (2) and what are their functions?
Definition
Lipase- forms monoglycerides and fatty acids and co-lipase

Colipase enables lipase to attach to lipid

Lipase hydrolyzes fatty acids in positions 1 and 3
Term
What two roles does CCK have?
Definition
Stimulates pancreas to release pancreatic lipase and colipase, phospholipases and cholesterol esterase
Stimulates the release of bile to help emulsify fat
Term
What do phospholipases do?
Definition
Hydrolyzes position 2 fatty acid
Term
What does Cholesterol esterase do?
Definition
Cleaves a fatty acid and cholesterol from a cholesterol ester
Term
Name the Lipoprotein Association and Function of Apo: A1, B48, B100, C1, C2, E
Definition
-apo-A-I

Chylomicrons, HDL

major protein of HDL, activates LCAT

-apo-B-48
Chylomicrons

exclusively found in chylomicrons, derived from apo-B-100 gene by RNA editing in intestinal epithelium; lacks the LDL receptor-binding domain of apo-B-100

-apo-B-100

VLDL, IDL and LDL

major protein of LDL, binds to LDL receptor; one of the longest known proteins in humans

-apo-C-I

Chylomicrons, VLDL, IDL and HDL

may also activate LCAT

-apo-C-II
Chylomicrons, VLDL, IDL and HDL

activates lipoprotein lipase

-Apo-E
(at least 3 alleles [E2, E3, E4] each of which have multiple isoforms)

Chylomicron remnants, VLDL, IDL and HDL

binds to LDL receptor, apo-Ee-4 allele amplification associated with late-onset Alzheimer's disease
Term
Describe exogenous lipid transport/chylomicrons and their fate (7)
Definition
Nascent chylomicron contains b-48 and A apolipoproteins

Apolipoproteins E and C are transferred to the chylomicron from HDL

Chylomicrons deliver the TAGs to other tissues other than the liver, particularly adipose and muscle

Adipose tissue and muscle cannot phosphorylate glycerol so transfers to the serum to be picked up by the liver or kidney

When much of the TAGs are transferred from the chylomicrons they become chylomicron remnants

The chylomicron remant transfers the apolipoproteins C back to HDL

The chylomicron remnant attaches to a liver binding site containing hepatic lipase, and the fatty acids, cholesterol, and cholesteryl esters are transferred to the liver
Term
Endogenous lipid transport/VLDL and their fate (6)
Definition
Nascent VLDL are made in the Golgi
apparatus of the liver.

Additional apolipoproteins C and E are
transferred from HDL.

The fatty acids from triacylglycerols
(TAG) are hydrolyzed by lipoprotein
lipase found in adipose, aorta, heart,
spleen, etc. (non-hepatic tissue).

As the TAG is removed from the VLDL
the particle becomes smaller and
becomes an IDL.

Further loss of TAG and it becomes a LDL.

LDL are taken up by B-100 receptors
found in the liver and non-hepatic tissue.
Term
Reverse cholesterol transport (7)
Definition
HDL is synthesized primarily in the liver with a lesser amount from the intestine. APO-E and APO-C are synthesized in the liver and added to HDL.

The nascent or discoidal HDL contains phospholipids (PL), cholesterol (C) and lecithin: cholesterol acyl transferase (LCAT).

Receptors of the adenosine triphosphate
(ATP)-binding cassette transporter family (ABCA1) transport cholesterol and PL to HDL unidirectionally.

Receptors of the scavenger receptor family (SR-B1) transfer the lipids bidirectionally.

As the HDL particle picks up PL and CE a
polar bilayer of PL is formed with a
non-polar core of C and CE.

The HDL spherical particle cycle in size and lipid content by transferring CE to the liver via SRB-1 site. PL is transferred to the liver and lysolecithin is transferred to albumin.

The life span of HDL is about 2 days and
during this time it actively works at the reverse transport of cholesterol to the liver for excretion via bile.
Term
What are the two essential fatty acid family starting points?
Definition
linoleic acid 18:2n6
a-linolenic acid 18:3n3
Term
What is the notation for arachidonic acid? y-linoleic acid?
Definition
Arachidonic 20:4n6

y-linoleic 18:3n6
Term
What is the only natural trans fatty acid?
Definition
18:1n9 (elaidic acid)
Term
Which FA desaturases do mammals have and lack?
Definition
have: Delta-9, delta-5 and delta-6

lack: delta-12 and delta-15
Term
What do COX (2) enzymes yield? LOX enzymes?
Definition
COX: prostaglandins (PG) and thromboxanes (TX)

LOX: leukotrienes (LT)
Term
Essential fatty acid precursors of eicosanoids (subtraction rule of eicosanoids)
Definition
Dihomo-γ-linolenic acid (DHGLA, C20:3, n-6) is the precursor or the 1-series of PGs and 3-series of LTs

Arachadonic acid (C20:4, n-6) yields the 2-series of PGs and 4-series of LTs

EPA (C20:5, n-3) yields the 3-series of PGs and 5-series of LTs
Term
Phospholipids function
Definition
structure (cell membranes), precursor for eicosanoids (locally active hormones), emulsifiers, energy
Term
Triglycerides function
Definition
energy storage, insulation, protective cushion
Term
Lipase and co-lipase
Definition
Colipase enables lipase to attach to lipid

Lipase hydrolyzes fatty acids in positions 1 and 3
Term
Risk factors for heart disease (the specific ones she gave us)
Definition
High LDL cholesterol
Low HDL cholesterol
Hypertension
Family history
Obesity
Diabetes
Gender
Systemic inflammation

High fat diet
Smoking
Infectious agents
Inactivity / Sedentary lifestyle
Term
Name the four functions of PGs listed
Definition
Smooth muscle cell contraction

Blood pressure regulation

Vasodilation

Platelet aggregation (some PGs reduce, some TXs increase)
Term
Thromboxane Roles (2)
Definition
Platelet aggregation (some PGs reduce, some TXs increase)

Vasoconstriction (TXs)
Term
What fat enzymes are inactive in premature infants? What does this result in?
Definition
Desaturases; results in an importance in the supplementation of EPA and DHA for optimum vision and learning
Term
Why would pancreatic lipase inhibition lead to weight loss?
Definition
People's ability to digest fats would go down, thus their calories would go down.
Term
Describe the process of atherosclerosis
Definition
LDLs that enter the tunica intima become oxidized, but oxLDL is cytotoxin, which activates endothelial cell immune response, which then causes monoctyes to enter tunica intima, differentiate to macrophages, and then look for the source of the problem, consume oxLDL but sometimes become overwhelmed and turn into foam cells. New/Additional Medial layer formed by an increase in and migration of smooth muscle cells to the intima (which are signaled to do so by cytokines), new layer then forms a fibrous cap of elastin, then the foam cells explodes and creates a necrotic core gruel (cereal), new foam cells being made degrade/eat the new elastin layer, then the endothelial tissue gets damaged and then platelet aggregation occurs because after the foam cells explode they become more active.
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