Carbohydrates Flashcards
1 gram of carbohydrate is =
4 kcal
1 g of protein =
4 kcal
1 g of fat =
9 kcal
Structural component of cells
Recognition molecule
Source of fats and amino acids
Carbohydrates
60-70% of total calories
Dietary Carbohydrates
the increase in blood glucose from the ingestion of a specific food in a given time period
Glycemic response
The concentration of blood glucose observed by consumption of a food, relative to that of a standard food
Glycemic index
Standard of gycemic index
Glucose
100
Dietary carbohydrates
Starch
Cellulose
Disaccharides
Monosaccharides
Starch undergoes hydrolysis by
Amylase
Prevents digestion of carbohydrates
Alpha glucosidase
Acarbose
Give with first spoonful of food
Specific amylase present in saliva
Hydrolyzes starch and it will break it down to maltose and dextrin
Ptyalin
Salivary amylase is responsible for cleavage of this section at this pH
Maltose
Maltotriose
Dextrose
Glucose
Alpha 1,4
Optimum pH 6.6-6.8
Remaining polymers of starch -> hydrolysis of amylopectin or glycogen
Limit dextrins
Dietary fibers
Cellulose Hemicellulose Pectins Mucilages and gums Lignin
Not enzymatically digested
Not a major source of nourishment
Dietary fibers
Acts on cellulose, hemicellulose, pectins, mucilages and gums and lignin to produce carbox dioxide, methane, water and H
bacteria
Absorption of monosaccharides is through
Simple passive diffusion
Facilitated diffusion
Active transport
Pentose/Glucose
Mode of transport
Simple passive diffusion
Fructose/Mannose/Glucose
Mode of transport
Facilitated diffusion
Glucose/Galactose
Mode of transport
Active transport
Due to inability to produce enough glycogen debranching enzyme (GDE)
Accumulation of limit-dextrin like structures in cytosol
Forbes-Cori disease
Glycogen storage Type III Disease
Limit dextrinosis
All cells
Glut 1 and 3
Liver and Pancreas SI
Glut 2
Muscle and fat
Glut 4
Gut and Small intestines
Glut 5
Lactose intolerance results from deficiency of
Beta galactosidase
Lactase deficiency
Undigested lactose hydrolyzed by bacteria Production of lactic acid, gas Diarrhea Abdominal distention Pain Low stool pH from lactic acid
Lactose intolerance
The gene responsible for making GDE (Glucosyl transferase and alpha 1,6 glucosidase) is the
AGL gene
Mirror images
Spatial relationship to the parent compound glyceraldehyde
Optically active
D and L isomers
Carbon: Hydrogen: Oxygen
1: 2: 1
When the OH group of C1 is pointing in the opposite direction to the carbon 6
Alpha glucose
Where the hydroxyl group of C1 and C6 is pointing in the same direction
Beta glucose
2 glucose molecules linked together by a 1,2,4 glycosidic bond
Maltose
Disaccharide
Process of linking monosaccharides with one another is called
Where this is released
Condensation
Water
This process breaks the alpha glycosidic bond by adding water
Hydrolysis
Galactose + Glucose
Linked by a?
Lactose
Beta 1,4 glycosidic bond
Disaccharide
alpha Glucose + beta Fructose
Linked by a bond called?
Sucrose
Glucose alpha 1 and fructose beta 2 bond
Disaccharide
Flipped
Table sugar
Formed by plants
Monosaccharides
Glucose
Galactose
Fructose
Short chain of monosaccharides less than 20 monosaccharides
Oligosaccharide
Glucose + Glucose + Glucose
Maltotriose
More than 20 monosaccharide bonds
Oli becomes
Polysaccharides
Glycans
Polysaccharide with single type of monosaccharide
Contain two or more types of monosaccharide
Homopolysaccharide
Heteropolysaccharide
Polysaccharides can be
Branched
Unbranched
Serve as storage form of polysaccharide in plants
Homopolysaccharide
Ex. starch made up of glucose
Branching between two glucose molecules in starch is at the
alpha 1, 6
If starch is unbranched, it contains
a 1,4 glycosidic bonds
Amylose
If starch is branched it contains
a 1-6 glycosidic bonds
a 1,4 glycosidic bonds
Amylopectin
Storage form of glucose in animals
Glycogen
Contains amylose and amylopectin
Branch points in glycogen occur every
8-12 glucose residues
Branch points in starch occur every
24-30 glucose residues
Structural components of bacteria and yeast made up of a 1,3 and alpha 1,6 bonds
May contain a 1,2 and a 1,4
Dextrans
Make up the plant cell wall
Unbranched homopolysaccharide consisting of thousands of glucose molecules
Glucose molecules have beta configuration
B 1,4 glycosidic bonds
Humans have no enzymes that hydrolyze B 1,4
Cellulose
Aldehydes or ketones that contain hydroxyl groups
Saccharon meaning sugar
Carbohydrates
Major product of digestion of carbohydrates
Glucose
Role of Glucose
Energy source Metabolic fuel and intermediates Structural framework of DNA and RNA Structural elements of living things Glycoconjugates serve as recognition sites of hormones, Ag specificity etc. Source of reducing equivalents (NADPH)
Sugar alcohols
Sorbitol
Mannitol
Xylitol
Fruits
50% of ingested glucose is converted to
Energy (Glycolysis)
The dominant product is pyruvate
Aerobic glycolysis
When oxygen is depleted, as for instance during prolonged vigorous exercise, the dominant product is
Lactate
30-40% of glucose is
converted to fat
10% of glucose is
converted to glycogen
The assimilation of food and its conversion into more useful forms for the maintenance of body processes
Nutrition
Amount of a nutrient considered adequate to maintain health
Recommended Nutrient Intake RNI
Least amount of nutrient that prevents deficiency
Minimum Daily Requirement
Impairment of health from defiency or excess of nutrients
Malnutrition
Mirror images
Spatial relationship to the parent compound Glyceraldehyde
Optically active
D and L isomers
Most abundant heteropolysaccharide
Glycosaminoglycans
Long unbranched polysaccharide
Highly negatively charged
High viscosity
Low compressibility
N-acetylgalactosamine
N-acetylglucosamine
Uronic acid - Glucuronate or iduronate
Dietary carbohydrates recommeded intake
55-70% of the total calories
At least 50-100gm DAILY
70% of the total carbohydrate intake should be
Complex
10% simple
“Equal”
“NutraSweet”
Nutritive
Dipeptide of aspartate and phenylalanine
200x as sweet as sucrose
Aspartame
Non-nutritive
350x as sweet as sucrose
Leaves a bitter aftertaste
High intakes lead to bladder cancer in animals
Saccharin
