Lecture 4 – Macronutrients Part 1 Flashcards

Flashcards covering the vocabulary and key concepts of macronutrients, specifically focusing on carbohydrate and protein chemistry, digestion, and metabolism.

Macronutrients

The study of energy-containing nutrients, primarily carbohydrates, protein, and fat, which sustain life processes.

Photosynthesis

The process by which plants use the energy of the sun to combine carbon dioxide ($CO_2$) and water ($H_2O$) to form starches.

Adenosine Triphosphate (ATP)

The form of stored biological energy created from enzymatic reactions; for example, one molecule of glucose can produce $32$ molecules of ATP.

Kilocalorie (kcal)

The technical unit of measurement for biological energy where $1\,kcal=1000\,cal$ and $1\,kcal=4.18\,kJ$.

Macronutrient Energy Values

Calculated as $4\,kcal/gram$ for carbohydrates, $4\,kcal/gram$ for protein, and $9\,kcal/gram$ for fat.

Bomb Calorimeter

A laboratory method used to determine calorie content by burning food in an insulated vessel and measuring the heat generated from combustion.

Monosaccharides

The simplest form of carbohydrates, including glucose, galactose, and fructose.

Glucose

Also known as blood sugar, it is the most abundant monosaccharide in nature and the preferred fuel for cells to make ATP.

Galactose

A component of the milk sugar lactose that is converted to glucose in the liver.

Fructose

Commonly known as fruit sugar, it is sweeter than table sugar and enters the bloodstream more slowly than glucose.

Disaccharides

Carbohydrates composed of two monosaccharides, including maltose, sucrose, and lactose.

Maltose

A disaccharide composed of glucose + glucose, found in beer, malted bread, and as a breakdown product of starch.

Sucrose

Commonly called 'white sugar,' it is composed of glucose + fructose and found in sugar cane and maple syrup.

Lactose

Known as milk sugar, it is composed of glucose + galactose and is produced by the mammary glands of animals.

Oligosaccharides

Short-chain polymers made of more than $2$ monosaccharides, such as Fructooligosaccharides (FOS).

Inulin

A dietary source of FOS found in Jerusalem artichokes and onions that is fermented in the colon by bacteria.

Polysaccharides

Long chains of monosaccharide units, including starch, glycogen, and fibre.

Starch

The most common digestible polysaccharide in plants, existing in two forms: amylose and amylopectin.

Glycogen

The major form of stored carbohydrate in animal tissues, localized primarily in the liver and skeletal muscle.

Salivary Amylase

The enzyme secreted in the mouth that begins the digestion of starch by breaking it into maltose and short-chain polysaccharides.

Pancreatic Amylase

An enzyme secreted by the pancreas into the small intestine to complete the breakdown of starch.

Brush Border Enzymes

Specific enzymes on the surface of the intestine, including lactase, maltase, and sucrase, which perform the final breakdown of disaccharides.

Active Transport

The rapid, energy-dependent method utilizing ATP and $Na/K$ pumps to move glucose and galactose into the bloodstream.

Facilitated Diffusion

The slower absorption method used by fructose which can lead to a build-up of sugar in the small intestine if consumed in excess.

Insulin

A hormone secreted by the pancreas to lower blood glucose levels by storing it in muscle and fat cells.

Glut1

Glucose transporters in the brain and red blood cells that remain in a constant open state to allow glucose inflow.

Glut4

Insulin-regulatable glucose transporters found in adipocytes (fat cells) and muscle cells.

Glucagon and Adrenaline

Hormones secreted to increase blood glucose levels by releasing stored glucose from the liver and muscle cells.

Glycaemic Index (GI)

A numerical scale standardized to white bread ($100$) that correlates the effect of various carbohydrates on blood glucose concentrations.

Glycogenesis

The metabolic pathway triggered by insulin that converts glucose into the storage molecule glycogen.

Glycogenolysis

The process stimulated by glucagon and adrenaline that breaks down stored glycogen into individual glucose units.

Gluconeogenesis

The creation of new glucose from non-carbohydrate sources, specifically by using the carbon skeletons of deaminated amino acids.

Glycolysis

The biochemical pathway in the cytosol that degrades one molecule of glucose into $2$ molecules of pyruvate to generate ATP.

Aerobic Metabolism

Energy production occurring in the presence of oxygen, utilizing the Kreb's Cycle to yield the bulk of cellular ATP.

Anaerobic Metabolism

Energy production without oxygen, where pyruvate is converted into lactate (lactic acid), often resulting in sore muscles.

Kreb's Cycle

Also known as the Citric Acid Cycle, it occurs in the mitochondria and completely oxidizes Acetyl-CoA to $CO_2$ and $H_2O$ for ATP production.

NADH and FADH2

Co-enzymes derived from Niacin (B3) and Riboflavin (B2) that transfer electrons to the electron transport chain.

Dietary Fibre

Heterogeneous plant substances resistant to human digestive enzymes, classified by their water solubility.

Cellulose

An insoluble fibre from plant cell walls found in bran, legumes, and root vegetables.

Pectin

A water-soluble and completely fermentable fibre found in apples, strawberries, and citrus fruits.

Lignans

Insoluble structural components found in root vegetables and linseeds that absorb water well and assist in toxin removal.

Amino Acids

The building blocks of protein, consisting of an amino group ($NH_3$) and a carboxylic acid group.

Pepsin

An enzyme that functions in the acidic environment of the stomach to break large proteins into smaller peptides.

Cholecystokinin (CCK)

A hormone that signals the brain for satiety, slows gastric emptying, and stimulates the pancreas to secrete alkaline juices.

Deamination

The process occurring in the liver where the amino group is removed from an amino acid, producing ammonia.

Urea Cycle

The pathway by which the liver converts toxic ammonia into urea for excretion by the kidneys.

Nitrogen Balance

A comparison of nitrogen consumption vs. excretion; zero balance indicates health, while negative balance occurs during infection or trauma.

Transcription

The process of copying DNA into messenger RNA (mRNA) within the cell nucleus.

Translation

The process occurring on the ribosome where mRNA is decoded into a sequence of amino acids to form a protein.

Complete Protein

Food that contains all essential amino acids in physiologically significant proportions, such as meat, eggs, and dairy.

Complementary Protein

The practice of combining different plant protein sources, such as rice and beans, to obtain a full complement of essential amino acids.

Serotonin

A neurotransmitter responsible for happiness and calm, which is synthesized directly from the amino acid tryptophan.

Melatonin

A hormone responsible for regulating sleep, synthesized from the amino acid tryptophan.