HN 307 Carbohydrates

What’s the difference between micro and macronutrients

Macro- provide NRG for body functions

Carb, protein, lipids

What are micronutrients?

Important molecules needed for body processes but only need small amounts

(ex: vitamins, minerals, trace elements)

The preferred NRG source of organisms is?

carbohydrates (mainly C, H, O)

Carbohydrates made of 1-2 sugars are called?

Simple carbs, easily digested

Complex carbohydrates are?

Carbs made of 3+ sugars, take longer to break down

The 3 monosaccharides are?

Glucose, fructose, galactose

The 4 types of disaccharides are?

Lactose, sucrose, maltose, trehalose

Lactose =

Glucose + galactose

Sucrose =

Glucose + fructose

Maltose and trehalose are both made of?

2 glucose molecules bonded

Fructose and galactose can be found in?

Fructose- fruits/honey, sweetner

Galactose- rare but in dairy

How are 2 monosaccharides bonded in a disaccharide?

Covalent glycosidic bond

Sucrose can be found in?

Beets, sugar cane, table sugar

A sugar often in made as byproduct of starch digestion and malted beverages?

Maltose

What’re the 3 types of oligosaccharides?

raffinose, stachyrose, verbacose (fructs + galactans)

What’s unique about oligosaccharides?

3-10 monomer sugars, cannot be digested → are prebiotics fermentable for gut bacteria

What’re 2 highly fermentable oligosaccharides?

Fructans, galactans

What would be in beans, broccoli, and whole grains as a good source of nutrition for gut bacteria?

Raffinose

What foods are avoided in low FODMAP diet?

Fermentable oligosaccharides (fructans / galactans)

Disaccharides (lactose)

Monosaccharides (sole fructose)

Polyols (mannitol, sorbitol)

Plants store NRG in what 2 forms of starch?

amylose + amylopectin

which is linear vs branched, amylose or amylopectin?

Amylose- linear so harder to digest (whole grains, legumes)

Amylopectin- branched, easier digestion

Animals store NRG as [ ] for short term reserve?

Glycogen

A polysaccharide that is insoluble and non fermentable:

Cellulose (dietary fiber)

What starts starch digestion in your mouth?

Salivary alpha amylase → break alpha (1-4) bond in starch + glycogen

What carb digestion occurs in the stomach?

None, amylases deactivated by HCl

What digests the carbs in small intestines?

Pancreas → pancreatic alpha-amylase → dextrins or maltose → glucose

What breaks down the disaccharides that are now in the small intestine?

Disaccharidases from microvilli (amylases not enough)

Maltase, Lactase, Sucrase

Why do people get stomach upsets from lactose intolerance?

No lactase to digest lactose → lactose in stomach pulls water into colon and bacteria ferment it→ gas and diarrhea

How is glucose sent to blood when it’s down the concentration gradient?

Facilitated diffusion→ GLUT 2 and GLUT 4 to transport into enterocyte

How is glucose sent to blood when it’s against the concentration gradient?

Active transport with sodium-glucose cotransporter 1:

1) Na+ pumped out via Na+/K+ pump

2) Na+ goes inside cell down gradient, gives NRG so glucose comes in

Why should fructose not be eaten alone?

Absorbed slower, can cause diarrhea

Take with glucose/galactose so GLUT2 receptors increase

How’re monosaccharides taken into the bloodstream?

enter liver via portal vein + facilitated diffusion, all basically converted to glucose

What happens to glucose in the liver?

1) used by liver

2) released into blood to keep glycemic level

3) stored as glycogen

What does insulin promote?

Glucose into glycogen in muscles + liver, reduces glucose production + breakdown to lower blood sugar level

How is insulin activated?

Beta cells (@ pancreas’ islet of langerhans) sense high blood sugar levels

The pancreas secretes insulin

How does insulin facilitate glucose uptake into cells?

Insulin binds to cell receptor

Signals GLUT 4 transporters to come up from vesicle onto surface

Glucose enters cell through GLUT4 transporter

Why does insulin resistance happen?

cells desensitized to insulin, more insulin made

→ with genetic factors + obesity

Insulin resistance can lead to?

Type 2 diabetes

Difference between diabetes type 1 + 2?

Type 1- immune cells destroy pancreas beta cells so NO insulin is made

type 2- not enough insulin is made as pancreas is overworked from insulin resistance; genetic + lifestyle habits

What does the glycemic index measure?

Increase in blood sugar level during a 2 hr period after eating a carbohydrate food = how quickly blood sugar is absorbed after being eaten

Temperature, growing conditions, food processing, insulin sensitivity, activity level, food’s ripeness/location affect?

Glycemic index score, so not actually very realistic and accurate to diet

What should you eat with carbs to lower the glycemic index?

Proteins

GlycoGENesis?

store glucose into glycogen (muscles + liver)

glycogenolysis=

break down glycogen into glucose

Glycolysis?

convert glucose into pyruvate → NRG

GlucoNEOgenesis?

Making glucose from non-carbohydrate sources

What stimulates glycogenesis?

High blood sugar level → insulin → muscles and liver to convert glucose to glycogen

Also by high ATP/AMP levels

What’re the general steps of glycogenesis?

Hexokinase/glucokinase converts glucose → glucose-6-phosphate

Then converted to glucose-1-phosphate

Added to chain of glycogen

How does glycogenesis differ in the liver vs muscle?

Muscle- hexokinase → glucose-6-phosphate limits how much glycogen can be stored

Liver- glucokinase → no limit to glucose storage

Which hormones are related to anabolic reactions?

Insulin, growth hormone, testosterone

Which hormones are related to catabolic reactions?

Glucagon, adrenaline, cortisol

What stimulates glycogenolysis?

Ep, norepinephrine, glucagon, high AMPT ratio → provide quick NRG

Glycogen can only be converted directly to glucose in?

Liver

What is made from glycolysis?

2 pyruvate

2 NADH

net gain 2 ATP (4 ATP made)

Parts of cell respiration happens in?

Glycolysis- cytoplasm

TCA cycle- mitochondrial matrix

ETC- inner mitochondrial membrane

What’s made from TCA cycle?

1 ATP

3 NADH

1 FADH2

CO2

What are the 2 e- carriers in the ETC?

NADH, FADH2

How many NADH and FADH2 go into the ETC?

4 NADH, 1 FADH2

How is NRG generated in the ETC?

NADH/FADH2 unload electrons through protein complexes → releases electric NRG

What is the purpose of the proton motor force?

e- through proteins fuel pumping H+ into inner mitochondrial membrane

ATP synthase turns ADP to ATP as H+ comes back into the matrix down concentration gradient

What is made through the ETC?

28-32 ATP

Water (O2 + H+)

Heat

NAD+ / FAD

What’re 2 forms of anaerobic respiration?

Lactate + Alcoholic fermentation

What happens after glycolysis in lactate fermentation?

Little ATP made

Pyruvate → lactate

Dehydrogenase cat. helps regenerate NAD+

why does lactic acidosis occur?

too much lactate in blood → pH dropping

Can lead to hypoxia, causing respiratory issues, heart failure, shock

A high VO2 max indicates what?

Body is more efficient at bring atm O2 to its cells

What can happen if exercise intensity exceeds the NRG made from aerobic respiration?

Switch to anaerobic metabolism (lactic acid fermentation) →

Can cause lactic acid buildup, fatigue, delayed-onset muscle soreness

What’s the primary reason for gluconeogenesis?

maintain blood sugar level when glycogen stores are out → use amino acids or glycerol to make glucose

Main location for flyconeogenesis?

Liver, little bit of kidneys

What can be used to make glucose in gluconeogenesis?

Lactate, glycerol, amino acids

How is lactate / Amino acids converted back to glucose?

Lactate → pyruvate

AA → malate

Turned into OXALOACETATE

oxalacetate -» phosphenolpyruvate

How is glycerol turned into glucose?

turned into dihydroxyacetone phosphate → to form G3P → reverse glycolysis steps to glucose

What is metabolic flexibility?

After gluconeogenesis starts, some people will use fats more than amino acids, and ability to use NRG from different sources not the same between people

How is high fructose corn syrup made?

Glucose + glucose isomerase turns corn syrup into 55% fructose

Why is pure fructose not good for the body?

Bypasses phosphofructokinase in glycolysis, which regulates it

• glycolysis is not controlled → too much acetyl CoA → fat is made

how can pure fructose affect the body?

More fats generated increase visceral fat → increased CVD(diabetes, heart disease, insulin resistance)

What’re 4 basically similar fructose + glucose products?

Honey < sucrose < high fructose corn syrup < agave syrup

What are the claims of the PO passive overconsumption model?

Calories in = calories out, all calories are the same

Eating high-fat foods contribute to weight gain

What’re the claims of the CIMO model?

Carbohydrates w/ high glycemic index → exaggerated insulin response → more fat/glycogen storage and obesity

Feel hungry soon since blood sugar rapidly decreases after

How is glycogen related to water?

Glycogen attracts and is bound to water

every gram glycogen = 3 g water

What’s considered a low-carb diet?

little simple carbs + starches

140 g or 20-30% daily carb intake

What’s in a keto diet?

Fats: 70-80% of cal intake

Low carb- less than 15 g; 5-10%

Proteins- 20% of cal intake

What’re the pros / cons of keto diets?

Take days to week for ketosis, keto-flu, LDL cholesterol, hard to keep up

Can be effective for short-term weight loss

In the keto vs plant-based diet, which diet lowered NRG intake?

plant-based

In the keto vs plant-based diet, which diet lowered glucose and insulin levels?

Keto

In the keto vs plant-based diet, which diet kept muscle mass, lower NRG density, and dietary fiber?

Plant-based

In the keto vs plant-based diet, which diet caused glucose tolerance?

Keto

In the keto vs plant-based diet, which diet showed higher glycemic load?

Plant-based

What counts under high-quality carbs?

Vegetables, legumes, fruits, whole grains

How much added sugars should we consume a day?

<10% of cal intake

What’re considered natural calorie sweeteners?

Sugar(sucrose), honey, maple syrup, agave nectar

What’re sugar alcohols?

Carbohydrates that are sugar/alcohol mixes

Less cals than sugar but are not really absorbed and ferment in the colon → GI problems

What’re the 4 sugar alcohols/polyols?

Xylitol, erythritol, maltitol/sorbitol

What’re included in low-cal sweeteners? (sugars not well absorbed)

Monk fruit extract, allulose, tagatose, stevia

What’re artificial sweetners?

Aspartame, saccharin, sucralose, acesulfame potassium