NUTR 301 Quiz #2

What does a BMI of < 18.5 indicate?

Low risk of co-morbitidies

What does a BMI of 18.5-24.9 indicate? >25?

• Average

• Overweight

What are the common health risks associated with obesity/high BMI?

Type 2 diabetes, Dyslipidemia, High BP, Metabolic syndrome

What is metabolic syndrome otherwise known as? What is it?

Syndrome X or insulin resistance syndrome

• Describes individuals more than just obese who are at risk of CVD and diabetes

What is the prevention for obesity?

Regulate energy intake

Regulate macro intake and EE

• Anti-obesity drugs

Is glucose a simple sugar?

Yes

Do most CHO come front plants or animals?

Plants

• Animals make complicated CHO for storage

  • Glycogen in muscle

What is the ending to naming an aldehyde?

-ose

• 1 aldehyde, 1C

What is the ending to naming a ketone?

-ulose

• 1 ketone, 2C

Name the names of sugars with 2, 3, 4, …. #C

Triose, tetrose, pentose, hexose, heptose, octose, nonose

How many C, H, O do all hexose sugars have?

6 C, 12 H, 6 O

What monosaccharides all have 6C?

Glucose, galactose, fructose

What is the difference between fructose vs glucose/galactose?

Fructose is a 5-sided ring

• others are 6-sided

What is the difference between glucose vs galactose?

Similar chemical structure but OH on C4 in opposite directions

How is a glycosidic bond formed? Where do they join?

Condensation reaction between 2 monosaccharides

• OH on 1 glucose bonds w/ H atom from other glucose

What is the difference between alpha and beta glycosidic bonds?

alpha: bond facing down

beta: bond facing up

What is sucrose?

Dissacharide

• Glucose bonded to fructose

• Table sugar (sweetener)

What is maltose?

Glucose bonded to glucose

What is lactose?

Glucose bonded to galactose

What is a reducing vs. non-reducing sugar?

Reducing: unsubstituted anomeric OH group

• reactive

What are the 4 types of polysaccharides?

1. Linear

2. Alternating branches consisting of a single sugar unit

3. Blocks of consecutive sugar unit branches

4. branches on branches

What is different about sugars that contain aldehyde groups?

They have an open chain form

• can be oxidized to carboxylic acids

• Reducing sugars

What should blood glucose levels always be?

5 mmol

What is the maillard rxn?

Aldoses/ketoses + amines (primary and secondary)

What happens when an aminoketose is formed?

Conversion to highly reactive dicarbonyl compound

What is formed w/ the amino group from an aminoketose?

Collagen-rich tissues

• cross-linked proteins

What can prolonged hyperglycemia cause?

Increased sugar rxns

What does the HbA1C test measure?

Avg blood glucose over lifespan of RBC (3 months)

What result from HbA1C is a measure for diabetes?

Above 6.5%

What does fiber stay intact when were eating it?

Humans lack digestive enzymes that hydrolyze B1-4 glycosidic bonds

• enzyme: cellulase

Which enzymes could degrade fiber?

What is the difference between starch vs. cellulose?

Starch: can break down

Cellulose: cannot break down

What do plant starches have?

Amylose and amylopectin

Resistance starch can be formed while ______

Cooking

What are the digestible polys?

Starch (amylose and amylopectin), Resistance starch, glycogen

What are the 2 major steps of CHO digestion?

1. Intraluminal (inside stomach) hydrolysis (amylases)

2. Membrane digestion (brush border)

Describe intraluminal hydrolysis

• Initial digestion: salivary amylase & continues w/ pancreatic amylase

What is salivary amylase deactivated by?

Stomach acid

What do pancreatic juices in SI do?

Neutralize acid

Describe membrane digestion

Maltose, maltotriose, trisaccharides, oligos, and alpha-limit dextrins (from starch hydrolysis) require further breakdown

What does salivary aplha-amylase do in amylose and amylopectin?

Hydrolyzes alpha-1,4 glycosidic bonds in amylose/amylopectin = forms dextrins

What happens in the stomach to amylose/amylopectin?

No digestion in stomach

• Activity of gastric juice destroys enzymatic activity of salivary alpha-amylase = dextrins pass unchanged into SI

What happens in the SI to amylose/amylopectin?

Pancreas releases pancreatic alpha-amylase into SI which hydrolyzes alpha-1,4 glycosidic bonds = dextrins broken down to maltose

What happens in the brush border to amylose/amylopectin?

Amylose: Maltose hydrolyzed by maltase = free glucose

Amylopectin: maltose hydrolyzed = free glucose

• alpha-1,6 glycosidic bonds in limit dextrins are hydrolyzed by alpha-dextrinase = glucose

What does the glycemic index tell us?

How easy to breakdown

• Increased glycemic index= broken down fast

• Non-digestible = decreased glycemic index

What are the final product of hydrolysis to amylose/amylopectin?

Amylose: maltose + maltotriose

Amylopectin: maltose + maltotriose + alpha-limit dextrins

Where are membrane transporters most concentrated?

In membranes near enzyme complexes

What brush border membrane enzymes does amylose vs amylopectin deal with? What types of bonds do they deal with?

Amylose: maltase + glucoamylase

• alpha 1,4

Amylopectin: Maltase + glucoamylase + isomaltase

• alpha 1,4 & alpha 1,6

What brush border enzyme does sucrose deal with? what bonds are included?

Sucrase

• alpha 1,2

• Monosaccharide product = glucose + fructose

Describe trehalose

Mushrooms

Alpha 1,1

BB enzyme: trehalase

Monosacc product: glucose

How are glucose/galactose vs fructose absorbed?

Glucose/galatose: into enterocytes by carrier-dependent energy-requiring active T

Fructose: facilitated diffusion

Does fructose absorb readily?

Yes

• Doesnt rise in blood

Once absorbed, where do monos circulate?

In liver via hepatic portal vein

What transporters are used when hexose conc in lumen is low? How do they exit the cells to get to the bloodstream?

Enter enterocytes via SGLT 1 and GLUT 5

Exit via GLUT2 to enter blood

What would cause GLUT2 to go to apical membrane from intracellular pool? What does this cause?

Consumption of sugar-rich meal

• Triples sugar uptake by enterocyte

What is an example of malabsorption?

Milk - requires lactase

• Undigested lactose = fermented by bacteria

• hydrolysis defect

How can you test for malabsorption?

Hydrogen breath test & stool acidity test

What are commonly accepted definitions of dietary fibre?

Edible carbohydrate polymers w/ 3 or more units which are not hydrolyzed by enzymes in SI of humans

• Naturally occurring in food

• have a physiological benefit to health

What bonds is the flat, ribbon-like structure stabilized by in cellulose?

Hydrogen bonds

What is the digestible and non-digestible parts of a plant cell?

Digestible: Cell lumen

Non digestible: Cell Wall

What is the distribution of a whole grain wheat kernel?

80% endosperm : increase starch/protein, decrease micros

15% bran : increase fibre, micros, antioxidants, phytos

5% germ : plant embryo

Which is more susceptible to irreversible retrogradation?

Amylose

• Amylopectin can reverse process w/ gentle heating

What are examples of food w/ resistant starch?

Unripe bananas

oats

cooked/cooled rice

beans/legumes

raw/cooked potatoes

What happens to cholesterol when you consume soluble fibre?

Decreases

What does indigestible fibre do to body?

Increase distention

• adding bulk w/ low energy density

• increase satiety

• decrease daily kcal

Is insoluble fibre fermentable?

No

• Poorly fermentable

Does soluble fibre speed up or delay gastric emptying?

Delay

• increase transit time

• delays nutrient abs

Soluble fibres attract water and do what to blood glucose?

Increase satiety

• Lower postprandial blood glucose

Does insoluble fiber increase or decrease transit time?

Decrease

• More fecal bulk

Where are insoluble fibres mainly found?

Whole grains and veggies

• lignin, cellulose, hemicelluloses

Why is the glycemic response lower with soluble fibre?

Decreased nutrition diffusion rates into blood

What does fibre do for enterohepatic circulation?

Prevents it

• fibre binds to FA, cholesterol, bile acids = prevents micelle formation, lipid abs

What does production of lactate mean for pH?

Decrease

What is propionate and acetate?

Energy source

made in liver

What is butyrate?

Energy source for colonocytes

What are the effects of short chains FA’s?

Increased water + sodium abs in colon

Increased mucosal cell proliferation

Provides energy

Acidifies luminal environment

What are SCFAs effect on luminal environment?

• Increased excretion of bile

• decreased solubility of free bile acids

• increased Ca binding

• decreased rate of conversion of primary bile acids to secondary

Fecal bulk increases as fermentability _____

Decreases

How does detoxification w/ fibre work?

Increase bulk = diluting effect on toxins = decreased contact time w/ intestinal wall

What do prebiotics do?

Stimulate growth of bacteria = beneficial effect

Through what processes what G6P be produced by?

1. Phosphorylation of free glucose

2. Glycogen degradation

3. Gluconeogenesis

G6P is the precursor for glycogen ______ and the _____pathway

• synthesis

• pentose phosphate pathway

The ____ can hydrolyze G6P to glucose

Liver

Glucose is metabolized by glycolysis to ______then further broken down to ______

• Pyruvate

• Acetyl-coA

What are precursors for gluconeogenesis?

Lactate and AA’s

How much glucose does the liver remove from portal vein circulation?

1/3

• fructose and galactose removed on 1st pass

• remaining glucose circulates to provide energy

  • stimulate insulin release

What processes/things can glucose be derived from?

1. diet

2. glycogen stores

3. endogenous synthesis (from gluconeogenic precursors - fat stores)

What are the fates of glucose?

• Precursor for synthesis of other CHO

  • mammary lactose, ribose for DNA

• sugar residues

  • glycoproteins, glycolipids

Which cells are very dependent on glucose as an energy source?

• RBC, nerves, intestinal mucosa, brain

What is the UL for plasma glucose level?

6

What is the mean for plasma glucose level?

5

What would ~80 mg/dl mean?

Decreased insulin secretion

What is the Lower Limit for plasma glucose level? What does this mean for body?

~4

• Increased glucagon secretion

• Increased epi secretion

What would a 50mg/dl plasma glucose level mean for the body?

• Decreased cognition behaviour

  • aberrant: seizure, coma

What plasma concentration is neuronal death?

~20 mg/dl

Difference between glycolysis vs complete oxidation

Glycolysis: produce some ATP (SLP), occurs in all cells in cytoplasm, anaerobic

Complete oxidation: Lots of ATP formed (Ox phos), Aerobic in mitochondria

For uncoupling, which step would you upregulate?

The 2nd step

If you were to run fast for a short time would you be coupling or uncoupling your systems?

Uncoupling

Does skeletal muscle and cardiac tissue do glycolysis and completely oxidize?

skeletal: glycolysis or completely oxidize or store as glycogen for use

cardiac: completely oxidize

What does cardiac muscle use as primary fuel source?

FA bc there is more mitochondria