Carbohydrates, Lipids, Proteins, and Alcohol: GOB Chemistry Study Notes

Carbohydrates

Complex Carbohydrates vs. Simple Carbohydrates

Carbohydrates are classified based on the number of sugar units they contain. Simple carbohydrates consist of one or two sugar units, while complex carbohydrates are composed of longer chains of sugar units.

• Simple carbohydrates: Glucose, fructose, sucrose, lactose. Digested quickly.

• Complex carbohydrates: Starch, glycogen, fiber. Digestion depends on the type; fiber is not fully digestible by humans.

Example: Table sugar (sucrose) is a simple carbohydrate; bread (starch) is a complex carbohydrate.

Soluble vs. Insoluble Fiber

Dietary fiber is a type of complex carbohydrate and is categorized as soluble or insoluble based on its interaction with water.

• Soluble fiber: Dissolves in water, forms a gel, lowers blood cholesterol, slows glucose absorption. Examples: oats, beans, apples, oranges.

• Insoluble fiber: Does not dissolve in water, adds bulk to stool, prevents constipation. Examples: wheat bran, whole grains, vegetables.

Example: Apple flesh contains soluble fiber; apple skin contains insoluble fiber.

Nutritive vs. Nonnutritive Sweeteners

Sweeteners are classified by their caloric content.

• Nutritive sweeteners: Provide energy (calories). Examples: table sugar, honey.

• Nonnutritive sweeteners: Provide little or no energy. Examples: sucralose, saccharin.

Recommended Sugar and Fiber Intake

Dietary guidelines recommend specific daily intakes for fiber and added sugar.

Age Group	Women	Men
Before age 50	25 g/day	38 g/day
After age 50	21 g/day	30 g/day

General recommendation: 14 grams of fiber per 1,000 calories. Added sugar: Women 24 g (6 tsp), Men 36 g (9 tsp) per day.

Carbohydrate Digestive Enzymes

Enzymes break down carbohydrates into absorbable units.

Enzyme	What it breaks down
Salivary amylase	Starch
Pancreatic amylase	Starch
Maltase	Maltose
Sucrase	Sucrose
Lactase	Lactose

Example: Lactase deficiency leads to lactose intolerance.

Primary vs. Secondary Lactose Intolerance

Lactose intolerance results from insufficient lactase enzyme production.

• Primary: Natural decrease in lactase with age.

• Secondary: Intestinal damage or illness reduces lactase production.

Type 1 vs. Type 2 Diabetes

Diabetes is a disorder of blood glucose regulation.

Type 1	Type 2
Little or no insulin produced; requires insulin treatment.	Insulin resistance; managed by lifestyle, medication, or insulin.

Glycemic Index (GI)

The glycemic index measures how quickly carbohydrate-containing foods raise blood glucose compared to a reference food.

• High GI: Rapid increase in blood glucose.

• Low GI: Slower increase.

Lipids

Triglycerides vs. Phospholipids

Lipids are a diverse group of biomolecules, including triglycerides and phospholipids.

• Triglycerides: One glycerol molecule attached to three fatty acids. Main form of fat storage and energy in the body.

• Phospholipids: Glycerol backbone, two fatty acid tails, and a phosphate-containing head. Major component of cell membranes; amphipathic (hydrophilic head, hydrophobic tails).

Example: Triglycerides are found in adipose tissue; phospholipids form the lipid bilayer of cell membranes.

Which Fatty Acid Has a Straight Chain?

Fatty acids differ in their structure based on the presence and type of double bonds.

• Saturated fatty acids: No double bonds; straight chains, pack tightly.

• Cis unsaturated fatty acids: Double bonds cause bends.

• Trans fatty acids: Trans double bond; straighter than cis, but not as straight as saturated.

Eicosanoids

Eicosanoids are signaling molecules derived from fatty acids. They regulate inflammation, blood clotting, and blood vessel function.

Essential Fatty Acids

Essential fatty acids must be obtained from the diet because the body cannot synthesize them.

• Linoleic acid (omega-6)

• Alpha-linolenic acid (omega-3)

Recommended Fat and Saturated Fat Intake

Dietary guidelines distinguish between total fat and saturated fat. It is important to limit saturated fat intake for cardiovascular health.

LDL vs. HDL Cholesterol

Cholesterol is transported in the blood by lipoproteins.

LDL (Low-density lipoprotein)	HDL (High-density lipoprotein)
"Bad" cholesterol; carries cholesterol to tissues, can contribute to plaque buildup.	"Good" cholesterol; carries cholesterol away from tissues to the liver.

R Component in Biomolecules

The R group in fatty acids refers to the hydrocarbon chain. In amino acids, the R group is the variable side chain that determines the amino acid's properties.

Proteins

Essential and Nonessential Amino Acids

There are 20 amino acids; 9 are essential and must be obtained from food, while 11 are nonessential and can be synthesized by the body.

• Essential amino acids: Cannot be synthesized; must be consumed.

• Nonessential amino acids: Can be synthesized by the body.

Example: Lysine is essential; alanine is nonessential.

Nutritional Concerns of a Vegetarian Diet

Vegetarian diets may lack certain nutrients if not properly planned.

• High-biological-value protein

• Riboflavin

• Vitamin D

• Vitamin B12

• Calcium

• Iron

• Zinc

Additional info: Complementary protein sources and fortified foods can prevent deficiencies.

Protein Sources in North America

About 70% of protein in the North American diet comes from meat, poultry, fish, milk, cheese, legumes, and nuts. Not all of this is animal protein.

Functions of Protein in the Body

Proteins serve many vital functions:

• Body structures (collagen, actin, myosin)

• Fluid balance (albumin)

• Acid-base balance (buffers)

• Hormones

• Enzymes

• Neurotransmitters

• Immune function (antibodies)

• Transport (hemoglobin, nutrient carriers)

• Glucose and energy (4 kcal/g)

Protein-Energy Malnutrition

Two main types:

Marasmus	Kwashiorkor
Develops slowly; severe deficiency of energy, protein, micronutrients.	Develops rapidly; severe protein deficiency, often with infection or disease.

Alcohol

Caloric Density of Alcohol

Alcohol provides 7 kcal per gram, higher than protein (4 kcal/g).

Alcohol Metabolism Pathways

Alcohol is metabolized by three main pathways:

• Alcohol dehydrogenase (ADH) pathway

• Microsomal ethanol-oxidizing system (MEOS)

• Catalase pathway

Alcohol is absorbed without digestion; 20% in the stomach, most in the small intestine. Food slows absorption.

Moderate Alcohol Intake

Definitions for moderate intake:

• Women: 1 standard drink/day

• Men: 2 standard drinks/day

• One standard drink: 14 g alcohol (beer: 12 oz, wine: 5 oz, liquor: 1.5 oz)

Amino Acids for Alcoholics

Alcohol abuse can cause protein-energy malnutrition and vitamin/mineral deficiencies. No specific amino acid is identified in the slides.