Carbohydrates CHEM 2030 Carbohydrates - PowerPoint Presentation

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Carbohydrates CHEM 2030 Carbohydrates - PPT Presentation

polyhydroxyaldehydes or polyhydroxyketones of formula CH 2 O n or compounds that can be hydrolyzed to them aka sugars or saccharides Monosaccharides carbohydrates that cannot be hydrolyzed to simpler carbohydrates eg Glucose or fructose ID: 734393

wadsworth glucose thomson 2008 glucose wadsworth 2008 thomson insulin diabetes blood carbohydrates sugar sugars body health pills effects starch fibers recommended carbohydrate

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Slide1

Carbohydrates

CHEM 2030Slide2

Carbohydrates

– polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH

, or compounds that can be hydrolyzed to them. (aka sugars or saccharides)

Monosaccharides

– carbohydrates that cannot be hydrolyzed to simpler carbohydrates; eg. Glucose or fructose.

Disaccharides

– carbohydrates that can be hydrolyzed into two monosaccharide units; eg. Sucrose, which is hydrolyzed into glucose and fructose.

Oligosaccharides

– carbohydrates that can be hydrolyzed into a few monosaccharide units.

Polysaccharides

– carbohydrates that are are polymeric sugars; eg Starch or cellulose.Slide3

Aldose

– polyhydroxyaldehyde, eg glucose

Ketose

– polyhydroxyketone, eg fructose

Triose, tetrose, pentose, hexose

, etc. – carbohydrates that contain three, four, five, six, etc. carbons per molecule (usually five or six); eg. Aldohexose, ketopentose, etc.Slide4

Epimers

– stereoisomers that differ only in configuration about

one

chiral center.Slide5
Slide6

23.2: Fischer Projections and the D, L Notation.

Representation of a three-dimensional molecule as a flat structure (Ch. 7.7). Tetrahedral carbon represented by two crossed lines:

vertical line is going back

behind the plane of the

paper (away from you)

horizontal line is coming

out of the plane of the

page (toward you)

carbon

substituent

(

)-(+)-glyceraldehyde

(

)-(-)-glyceraldehydeSlide7

before the

convention, stereochemistry was related to (+)-glyceraldehyde

D-glyceraldehyde L-glyceraldehyde

-(+)-

glyceraldhyde

S-(-)-glyceraldhyde (+)-rotation = dextrorotatory = d (-)-rotation = levorotatory =

lD-carbohydrates have the -OH group of the highest numbered chiral carbon pointing to the right in the Fischer projection as in R-(+)-glyceraldhydeFor carbohydrates, the convention is to arrange the Fischer

projection with the carbonyl group at the top for aldoses and closest to the top for ketoses. The carbons are numbered from top to bottom. Slide8

Carbohydrates are designated as D- or L- according to the

stereochemistry of the highest numbered chiral carbon of the

Fischer projection. If the hydroxyl group of the highest numbered

chiral carbon is pointing to the right, the sugar is designated as

(

Dextro

: Latin for

on the right side

). If the hydroxyl group is pointing to the left, the sugar is designated as L (Levo: Latin for on the left side). Most naturally occurring carbohydrates are of

the D-configuration. Slide9

23.3: The Aldotetroses.

Glyceraldehyde is the simplest

carbohydrate (C

, aldotriose, 2,3-dihydroxypropanal). The next

carbohydrate are aldotetroses (C

, 2,3,4-trihydroxybutanal). Slide10

Manipulation of Fischer Projections

Fischer projections can be rotate by 180° (in the plane of

the page

) only!

180°

Valid

Fischer

projection

Valid

Fischer

projectionSlide11

a 90° rotation inverts the stereochemistry and is illegal!

90°

This is not the correct convention

for Fischer projections

Should be projecting toward you

Should

be projecting away you

This is the correct convention

for Fischer projections and is

the enantiomerSlide12

If one group of a Fischer projection is held steady, the other

three groups can be rotated clockwise or counterclockwise.

120°

120°Slide13

Symmetry

Monarch butterfly:

bilateral symmetry=

mirror symmetry

Whenever winds blow

butterflies find a new place

on the willow tree

-Basho (~

1644 - 1694)

I anticipate

organic chemistry class

highlight of my day

- RizzoSlide14
Slide15

(+)-glucose? An

aldohexose

Emil Fischer (1902)

Four chiral centers, 2

= 16 stereoisomersSlide16

Epimers

– stereoisomers that differ only in configuration about

one

chiral center.Slide17
Slide18

Addition of alcohols to aldehydes/ketones:Slide19
Slide20
Slide21
Slide22
Slide23
Slide24

Disaccharides:

(+)-maltose “malt sugar”

two glucose units (alpha)

(+)-cellobiose

two glucose units (beta)

(+)-lactose “milk sugar” galactose & glucose (+)-sucrose “table sugar”

glucose & fructoseSlide25
Slide26
Slide27

Polysaccharides

starch

cellulose

Starch 20% amylose (water soluble)

80% amylopectin (water insoluble)

amylose + H2O  (+)-maltose

(+)-maltose + H

O  (+)-glucose

starch is a poly glucose (alpha-glucoside to C-4)Slide28

Amylopectin + H

 (+)-maltose

(+)-maltose + H

O  (+)-glucose

Also a polyglucose, but branched every 20-25 units:Slide29

Cellulose is a polyglucose with a beta-linkage:Slide30
Slide31

The Complex Carbohydrates

Fiber Sources

Dietary fibers are found in plant foods.

Functional fibers are health-benefiting fibers that are added to foods or supplements.Total fiber considers both dietary and functional fibers.Resistant starches escape digestion and are found in legumes, raw potatoes and unripe bananas.

Phytic acid or phytate has a close association with fiber and binds some minerals.Slide32

Digestion and Absorption of Carbohydrates

Carbohydrate Digestion

In the mouth, the salivary enzyme amylase begins to hydrolyze starch into short polysaccharides and maltose.

In the stomach, acid continues to hydrolyze starch while fiber delays gastric emptying and provides a feeling of fullness (satiety).Slide33

Digestion and Absorption of Carbohydrates

Carbohydrate Digestion

In the small intestine, pancreatic amylase among other enzymes (maltase, sucrase, and lactase) hydrolyzes starches to disaccharides and monosaccharides.

In the large intestine, fibers remain and attract water, soften stools and ferment.Slide34

Digestion and Absorption of Carbohydrates

Carbohydrate Absorption

Primarily takes place in the small intestine

Glucose and galactose are absorbed by active transport.Fructose is absorbed by facilitated diffusion.Slide36

Fig. 4-11, p. 110

Monosaccharides, the end products of carbohydrate digestion, enter the capillaries of the intestinal villi.

In the liver, galactose and fructose are converted to glucose.

Small intestine

Monosaccharides travel to the liver via the portal vein.

Stepped ArtSlide38

Digestion and Absorption of Carbohydrates

Lactose Intolerance

Symptoms include bloating, abdominal discomfort, and diarrhea.

Causes include lactase deficiency due to a natural decrease that occurs with aging or damaged intestinal villi.PrevalenceLowest in Scandinavians and northern EuropeansHighest in Southeast Asians and native North AmericansSlide39

Digestion and Absorption of Carbohydrates

Lactose Intolerance - Dietary Changes

Increase consumption of milk products gradually.

Mix dairy with other foods.Spread dairy intake throughout the day.Use of acidophilus milk, yogurt, and kefir (fermented products)

Use of enzymesIndividualization of dietsMust be careful that vitamin and mineral deficiencies do not developSlide40

Glucose in the Body

A Preview of Carbohydrate Metabolism

The body stores glucose as glycogen in liver and muscle cells.

The body uses glucose for energy if glycogen stores are available.If glycogen stores are depleted, the body makes glucose from protein.

Gluconeogenesis is the conversion of protein to glucose.Protein-sparing action is having adequate carbohydrate in the diet to prevent the breakdown of protein for energy.Slide41

Glucose in the Body

A Preview of Carbohydrate Metabolism

Making ketone bodies from fat fragments

The accumulation of ketone bodies in the blood is called ketosis.Ketosis upsets the acid-base balance in the body.The body can use glucose to make body fat when carbohydrates are consumed excessively.Slide42

Glucose in the Body

The Constancy of Blood Glucose

Maintaining Glucose Homeostasis

Low blood glucose may cause dizziness and weakness.High blood glucose may cause fatigue.Extreme fluctuations can be fatal.Slide43

Glucose in the Body

The Constancy of Blood Glucose

The Regulating Hormones

Insulin moves glucose into the cells and helps to lower blood sugar levels.Glucagon brings glucose out of storage and raises blood sugar levels.

Epinephrine acts quickly to bring glucose out of storage during times of stress.Balance glucose within the normal range by eating balanced meals regularly with adequate complex carbohydrates. Blood glucose can fall outside the normal range with hypoglycemia or diabetes.Slide44

Glucose in the Body

The Constancy of Blood Glucose

Diabetes

Type 1 diabetes is the less common type with no insulin produced by the body.Type 2 diabetes is the more common type where fat cells resist insulin.Prediabetes is blood glucose that is higher than normal but below the diagnosis of diabetes.Hypoglycemia is low blood glucose and can often be controlled by dietary changes.Slide46

Glucose in the Body

The Constancy of Blood Glucose

Glycemic response is how quickly the blood glucose rises and elicits an insulin response.

Glycemic index classifies foods according to their potential for raising blood glucose.Glycemic load refers to a food’s glycemic index and the amount of carbohydrate the food contains. The benefit of the glycemic index is controversial.Slide47

Health Effects and Recommended Intakes of Sugars

Sugar poses no major health problem except dental caries.

Excessive intakes may displace nutrients and contribute to obesity.

Consuming foods with added sugars should be limited. Naturally occurring sugars from fruits, vegetables and milk are acceptable sources.Slide49

Health Effects and Recommended Intakes of Sugars

Health Effects of Sugars

Foods with added sugars have sugars listed as a first ingredient.

Nutrient deficiencies may develop from the intake of empty kcalories. Just because a substance is natural does not mean it is nutritious. (Example: honey)Dental caries may be caused by bacteria residing in dental plaque and the length of time sugars have contact with the teeth.Slide50

Fig. 4-14, p. 119

Enamel

Caries

Gum

Pulp (blood vessels, nerves)

Bone

Root canal

Nerve

Blood vessel

Crown

Stepped Art

DentinSlide52

Health Effects and Recommended Intakes of Sugars

Controversies Surrounding Sugars

Excessive sugar intake can contribute to the development of body fat.

Sugar may be able to alter blood lipid levels and contribute to heart disease in some.There is no scientific evidence that sugar causes misbehavior in children and criminal behavior in adults.

There is a theory that sugar increases serotonin levels, which can lead to cravings and addictions.Slide53

Health Effects and Recommended Intakes of Sugars

Recommended Intakes of Sugars

The USDA Food Guide states that added sugars can be included in the diet as part of discretionary kcalories.

Dietary Guidelines state to limit intake of foods and beverages that are high in added sugars.DRI suggest added sugars should contribute no more than 25% of a day’s total energy intake.Slide54

Health Effects and Recommended Intakes of Starch and Fibers

Health Effects of Starch and Fibers

May be some protection from heart disease and stroke

Soluble fibers bind with bile and thereby lower blood cholesterol levels.Fiber may also displace fat in the diet.

Reduce the risk of type 2 diabetes by decreasing glucose absorptionEnhance the health of the GI tract which can then block the absorption of unwanted particlesMay protect against colon cancer by removing potential cancer-causing agents from the bodySlide55

Health Effects and Recommended Intakes of Starch and Fibers

Health Effects of Starch and Fibers

Promote weight control because complex carbohydrates provide less fat and added sugar.

Harmful effects of excessive fiber intakeDisplaces energy and nutrient-dense foodsAbdominal discomfort and distention

May interfere with nutrient absorptionSlide56

Health Effects and Recommended Intakes of Starch and Fibers

Recommended Intakes of Starch and Fibers

RDA for carbohydrate is 130 g per day, or 45-65% of energy intake.

Daily Value is 300 grams per day.Dietary Guidelines encourage a variety of whole grains, vegetables, fruits and legumes daily.

Healthy People 2010 recommends six servings of grains and five servings of fruits and vegetables.Slide57

Health Effects and Recommended Intakes of Starch and Fibers

Recommended Intakes of Fiber

FDA recommends 25 grams for a 2,000-kcalorie diet.

DRI at 14 g per 1000 kcalorie intake (28 grams for a 2,000 kcalorie diet)American Dietetic Association recommends 20-35 g per day.World Health Organization suggests no more than 40 g per day.Slide58

Health Effects and Recommended Intakes of Starch and Fibers

From Guidelines to Groceries

Grains

– encourage whole grainsVegetables – starchy and nonstarchy vegetables differ in carbohydrate content

Fruits – vary in water, fiber and sugar contentMilks and Milk Products – contain carbohydrate; cheese is lowMeat and Meat Alternates – meats are low but nuts and legumes have some carbohydrate

Food labels list grams of carbohydrate, fiber and sugar; starch grams can be calculated.Slide60

Alternatives to SugarSlide62

Artificial Sweeteners

Also called nonnutritive sweeteners

Saccharin

Used primarily in soft drinks and as a tabletop sweetenerRapidly excreted in the urineDoes not accumulate in the bodyHas been removed from list of cancer-causing substancesSlide63

Artificial Sweeteners

Aspartame

General purpose sweetener

Warning about phenylalanine for those with PKUControversial finding that aspartame may have caused cancer in ratsExcessive intake should be avoided by those with epilepsySlide64

Fig. H4-2, p. 134

Aspartic acid

Phenylalanine

Stepped Art

Methyl group hydrolyzed

Oxidized

Methanol

Carbon dioxide

FormaldehydeSlide66

Artificial Sweeteners

Acesulfame-K (acesulfame potassium)

Research confirms safetySlide67

Artificial Sweeteners

Sucralose

Made from sugar

Passes through digestive tractNeotameMost recent on the marketVery sweetPhenylalanine not an issueSlide68

Artificial Sweeteners

Tagatose

Used for foods and beverages

Provides less kcalories than sugarHigh doses can cause flatulence and loose stools.Alitame and CyclamatePending FDA approvalApproved in other countriesSlide69

Artificial Sweeteners

Acceptable Daily Intake (ADI) is the level of consumption, maintained every day and still safe by a wide margin.

Moderation and variety are still recommended.

Artificial Sweeteners and Weight ControlMuch research still being doneUsing artificial sweeteners will not automatically reduce energy intake.Slide70

Stevia – An Herbal Alternative

Lacks research

Classified as a dietary supplement

Not required to have testing and FDA approvalSlide71

Sugar Replacers

Also called nutritive sweeteners, sugar alcohols, and polyols

Maltitol, mannitol, sorbitol, xylitol, isomalt, and lactitol

Absorbed more slowly and metabolized differently in the bodyLow glycemic responseSide effects include GI discomfortSlide72

What Is Diabetes?Slide73

Learning Points

Know the difference between Type 1 and Type 2 diabetes

Know the job of glucose

Know the job of insulin

List some health factors related to getting Type 2 diabetesSlide74

Type 1 Diabetes

Body does not make insulin

Usually develops in children or young adults

Normal Weight

Must take insulin daily to liveSlide75

Type 2 Diabetes

Cells do not use insulin properly

Not enough insulin being produced

Generally develops in adulthood

Becoming more common in children due to obesityCommon in persons who are overweightMany different ways to treat, including diet and exercise, pills, or insulinSlide76

Type 2 Diabetes, Key Concepts

Obesity

Insulin Resistance

Elevated Insulin Levels

Reduced ability to make insulinSlide77

Insulin Resistance

Common in persons who are overweight

Insulin not as effective, and does not allow glucose into cells efficiently, causing blood sugar levels to rise

There is enough insulin activity to prevent diabetic comaSlide78

What Is Diabetes:

How Insulin Works

Insulin

Insulin ReceptorSlide79

How Insulin Works

Insulin is a hormone made in your pancrease

It works like a key to unlock cells so that blood sugar (glucose) can enter

Glucose is then used by the body as fuelSlide80

What Is Diabetes:

How Insulin Works

cell

Receptor Site

Insulin Fills

Receptor Sites

Insulin Passageways

cell

insulin

glucose

glucoseSlide81

What Is Diabetes: Insulin Resistance Due to Excess Weight

insulin

glucose

cell

glucose

glucoseSlide82

What Is Diabetes: Normal Blood Glucose & Insulin LevelsSlide83

Diabetes Pills: Oral

MedicationsSlide85

Diabetes Pills:

Sulfonylureas

These tell the pancreas to make more insulinSlide86

Diabetes Pills:

Names of Sulfonyureas

Brand Name

Generic Name

Diabeta

Micronase

Glynase

glyburide

Glucotrol

Glucotrol XL

glipizide

Amaryl

glimepirideSlide87

Diabetes Pills:

Things to know about sulfonylureas

Main thing to watch out for is having too many

low blood sugars

. If this happens, your doctor will give you a lower dose.Take the same way everydayGlucotrol XL cannot be crushed or cut in half; might see its empty shell in toiletSlide88

Diabetes Pills:

Metformin

Tells the liver to stop sending out sugarSlide89

Diabetes Pills:

Metformin

Comes as generic metformin or brand name Glucophage

Also comes in a long-acting formSlide90

Diabetes Pills:

Things to know about metformin

Can help people lose some weight

Main side effects are upset stomach and diarrhea

These usually get better after about 1 week Taking with food can help

Does not cause blood sugar to go too lowCannot be used in kidney disease or certain kinds of heart failure. Talk with doctor if you have these.

Contact doctor if you notice new fatigue, nausea, muscle pain/weakness, or fast breathing because these could be signs of a serious side effectSlide91

Diabetes Pills:

Glitazones

These help insulin in your body work betterSlide92

Diabetes Pills:

Names of Glitazones

Avandia and Actos

Only come as brand name pillsSlide93

Diabetes Pills:

Things to know about glitazones

The more common side effects of these are weight gain and swelling

People with heart failure should discuss this with their doctor before taking

Occasional blood work to test the liver is recommended, although liver problems on this medicine are very rareThese pills usually take 6 to 12 weeks before you can see their full benefit on blood sugarThese are expensiveSlide94

Diabetes Pills:

Meglitinides

These tell the pancreas to make more insulin

These are taken with meals, so you skip a dose if you skip a mealSlide95

Diabetes Pills:

Names of Meglitinides

Prandin® and Starlix®

Only come as brand name pillsSlide96

Diabetes Pills:

Meglitinides

Things to know

Main side effect to watch out for is low sugars