PRINCIPLES OF HUMAN NUTRITION Flashcards
WHAT IS METABOLISM?
The ensemble of chemical reactions that either provide energy from nutrients for the body to use (CATABOLISM) or provide energy storage when the body has enough energy (ANABOLISM).
- all reactions tightly regulated by hormones
WHAT ARE NUTRIENTS AND WHAT ARE THE 6 MAIN CATEGORIES?
Molecules we ingest used by an organism to survive, grow and reproduce.
6 categories: sugars, proteins, fats, vitamins, minerals and water
WHAT ARE MACRONUTRIENTS?
- nutrients consumed in large quantities
- involved in energy production, growth and repair
- e.g. carbs, proteins, lipids, water, calcium, sodium, potassium, magnesium, chloride, phosphorus, sulfur
WHAT ARE MICRONUTRIENTS? (‘TRACE ELEMENTS’)
- nutrients consumed in smaller quantities, but can still be essential
- important in metabolism, often acting as coenzymes or cofactors
- e.g. zinc, copper, selenium and iodine
WHAT AMOUNT OF ENERGY IS RELEASED PER g OF MAIN NUTRIENTS?
CARBOHYDRATES and PROTEIN: 4kcal
LIPIDS: 9kcal
WHAT ARE ESSENTIAL NUTRIENTS?
Nutrients which cannot be synthesized by the human body. E.g. vitamins or some amino acids (9/20 are essential, like omega 3 and 6)
WHICH ESSENTIAL NUTRIENT CAN ACTUALLY BE SYNTHESIZED, AND HOW?
Choline (can be synthesized from Phosphatidyl choline)
WHAT IS THE MAIN SOURCE OF ENERGY FOR BRAIN AND ERYTHROCYTES?
Carbohydrates
DIGESTION OF WHICH CARBOHYDRATE PROVIDES THE MAJORITY OF GLUCOSE IN HUMAN NUTRITION?
STARCH
WHAT ARE THE CATEGORIES OF CARBOHYDRATES?
Mono-, Di- and Polysaccharides
+ Oligosaccharides
WHAT IS THE GENERAL CHEMICAL FORMULA OF MONOSACCHARIDES?
Cx(H20)x
Which carbohydrates can’t be digested beyond their form? (cannot be further hydrolyzed)
Monosaccharides
3 examples of monosaccharides & the amount of carbons they have:
Glucose, fructose and galactose, all are HEXOSES (6 carbons)
IS GLUCOSE A KETOSE (contains keto group) or ALDOSE (contains aldehyde group)?
ALDOSE
IF A SUGAR HAS 5 OR MORE CARBONS IS IT MORE LIKELY TO FORM A LINEAR OR RING STRUCTURE?
RING
THE 2 ENANTIOMERS (D and L) OF MONOSACCHARIDES TAKE WHICH GROUP AS A REFERENCE?
HYDROXYL GROUP (OH)
CAN HUMANS METABOLIZE D OR L SUGARS?
ONLY D SUGARS,
WHERE ARE DISACCHARIDES BROKEN DOWN?
SMALL INTESTINE (brush border)
ARE DISACCHARIDES WATER SOLUBLE?
YES
3 DISSACHARIDE EXAMPLES AND THEIR COMPOSITION:
SUCROSE (GLUCOSE + FRUCTOSE)
MALTOSE (GLUCOSE + GLUCOSE)
LACTOSE (GLUCOSE + GALACTOSE)
HOW ARE MONOSACCHARIDES COMBINED IN DISACCHARIDES?
via GLYCOSIDIC BOND
HOW ARE DISACCHARIDES BROKEN DOWN?
By digestive enzymes which break down glycosidic bonds
WHAT ARE THE FUNCTIONS OF POLYSACCHARIDES?
storage of energy for later use, structural strength, lubrication
WHICH STRUCTURAL FORMS CAN THE POLYSACCHARIDES HAVE?
LINEAR and BRANCHED
HOW ARE MONOSACCHARIDES LINKED POLYSACCHARIDES?
by alpha 1-4 glycosidic bonds or alpha 1-6 glycosidic bonds
EXAMPLES FOR POLYSACCHARIDES WITH ALPHA 1-4 BONDS AND ALPHA 1-6 BONDS?
1-4: AMYLOSE
1-6: AMYLOPECTIN and GLYCOGEN
WHAT ARE GLYCOAMINOGLYCANS + ONE EXAMPLE
Molecules that combine polysaccharides and proteins. They are a part of the cell membrane and components of the synovial fluid. The large amounts of sugars on proteins creates a viscous fluid which gives them their properties. E.g. HYALURONIC ACID
WHAT ARE THE FUNCTIONS OF LIPIDS?
Metabolic messengers, regulators, cushioning for internal organs, insulation, absorption of ADEK vitamins..
HOW MANY KG OF ADIPOSE TISSUE (TRYGLICERIDES) ARE THERE IN A 70KG ADULT HEALTHY MALE AND HOW MUCH CALORIES CAN BE GENERATED FROM THAT?
11kg, 100 000 kcal
WHAT IS THE FORM OF LIPID STORAGE IN HUMANS CALLED?
Triglycerides
WHAT ARE PROTEINS?
Polymers of amino acids (MORE THAN 100) linked by peptide bonds
HOW MANY AMINO ACIDS ARE THERE IN NATURE AND HOW MANY IN HUMANS?
300 in nature, 20 in humans
WHAT ARE THE FUNCTIONS OF PROTEINS?
structural function, enzymes, hormones, receptors, channels…. THEY PARTICIPATE IN THE INTEGRITY OF THE CELL
WHAT ARE THE STRUCTURAL COMPONENTS OF AMINO ACIDS?
CARBOXYLIC ACID GROUP (COOH), AMINE GROUP (NH2) and THE ‘R’ GROUP
WHAT ARE THE POLYMERS OF LESS THAN 100 AMINO ACIDS CALLED?
peptides
WHAT IS THE DETERMINANT OF PROTEIN STRUCTURE?
AMINO ACID SEQUENCE
WHY ARE THE SECONDARY, TERTIARY AND QUATERNARY PROTEIN STRUCTURES 3D?
As a result of FOLDING (of amino acid sequences)
ENZYMES AND IMMUNOGLOBINS HAVE WHICH PROTEIN STRUCTURE?
Tertiary: protein chains folded into globular shapes
HOW MUCH OF THE ENERGY PRODUCED IN CATABOLIC PATHWAYS IS USED AS HEAT, AND HOW MUCH TO SUPPORT BODILY FUNCTIONS?
60% heat, 40% functioning
WHAT MAKES ATP A HIGH ENERGY COMPOUND?
The high-energy bond between 2nd and 3rd phosphate groups
GIVE OVERVIEW OF CATABOLISM OF MAIN NUTRIENTS
sugars - monosaccharides - undergo glycolysis - pyruvate
lipids - fatty acids + glycerol - undergo beta oxidatation - acetylCoA
proteins - amino acids (shouldn’t be further digested)
WHICH OF THE FOLLOWING DOESN’T RESULT IN PRODUCTION OF ENERGY STORAGE: GLYCOGENESIS, LIPOGENESIS, GLUCONEOGENESIS
Gluconeogenesis
WHAT IS THE PRODUCT OF GLYCOGENESIS AND WHERE IS IT STORED
Glycogen, mostly in liver + small amount in skeletal muscle
WHAT IS USED TO PRODUCE GLUCOSE DURING GLUCONEOGENESIS AND WGERE DOES THIS PROCESS OCCUR?
pyruvate, glycerol and amino acids are used, takes place in the liver
