Chap 5 and part of 8 Flashcards
Monosaccharides
(simple carbs) 1 sugar unit
- glucose
- fructose
- galactose
Disaccharides
(simple carbs (2 sugar units)
2 monosaccharides bound by a condensation bond.
Alpha and beta
oligasaccarides
Complex sugar (3-10 units of sugar= saccharides)
e.g. raffinose and stachyose
mainly indigestible, may cause discomfort
polysaccharides
Complex sugars (>10 units)
many monosaccharides bound
starch, glycogen, cellulose and fibre
digestibility depends on alpha and beta glycosidic bonds
Sucrose
glucose + fructose
alpha 1,2 glycosidic bond
Monosaccharides
(simple carbs) 1 sugar unit 6 carbon single unit: - glucose - fructose - galactose sugar alcohols: Xylitol, mannitol and sorbitol 5 carbon single unit: Ribose deoxyribose
Maltose
glucose + glucose
alpha 1,4 glycosidic bond
C12 H22O11
Verbacose
glucose + galactose + Fructose
complex carbohydrates
Oligosaccharides and polysaccharides
starch, glycogen and fibre
Simple Carbohydrates
monosaccharides and disaccharides
Carbohydrates
chemical structure
roles
chemical structure:
Carbon, hydrogen and Oxygen
monomer= saccharide
produced by plants via photosynthesis (glucose)
roles:
basis of structural tissue found in plants
source of energy and blood glucose homeostasis. Substrate in the biosynthesis of other compounds.
cell to cell recognition and communication: saccharides used in formation of glycoproteins that sit on surface of cells.
glucose
C6H12O2
Most abundant monosaccharide
consumed as sucrose (glucose + fructose)
Most of glucose cell uptake is insulin dependent via glucose transporter 4 (GLUT 4)
glucose uptake by liver is not insulin dependent
Lactose
galactose + glucose
beta 1, 4 glycosidic bonds
milk sugar
Type 1 diabetes
Autoimmune disease beta cells of pancreas are destroyed- no insulin produced symptoms: excessive urination dehydration/ thirst thrush/ genital itching slow to heal wounds blindness/ blurred vision tired/ lethargic weight loss treatment: drugs
Type 2 diabetes
Lifestyle related
either not enough insulin is produced/ cells aren’t responding as well to insulin. pancreatic beta cells are exhausted/ fail
glucose levels in blood rise/ insulin levels rise
symptoms:
excessive urination
thirst
blurred vision
tiredness
weight loss
treatment: diet/ lifestyle changes- drugs.
Alcohol metabolism
3 pathways
- alcohol dehydrogenase
- MEOS
- catalase
all produce Acetaldehyde—> (aldehyde dehydrogenase) –> acetyl CoA– > citric acid cycle.
Standard drink in Aus
10g of alcohol
what is standard drink based on
assumption that the liver metabolises 10g of alcohol per hour (varies between 5-10 g depending on body size and sex)
specific gravity of alcohol
0.789
specific alcohol in a drink
ml * % * specific gravity of alcohol
Standard drinks
specific alcohol divided by ten.
Fructose
Carbonyl group on the C-2 not the C-1.
sweetest monosaccharide
cell uptake is not insulin dependent!
large consumption linked with fatty liver disease (doesn’t require any transporters- therefore taken up easier by the body, the pathway to glyceraldehyde (2steps Verse 4)
therefore the pool of pyruvate is increased much faster with fructose. Exess goes to fatty acid synthesis for storage.
Is honey a healthier option
no. still contains plenty of carbs.
indigestible polysaccharides
Fibre
Fibre
The fraction of the edible part of the plant, or their extracts, or analogous carbohydrates that is resistant to digestion and absorption in the human intestine, usually with complete or partial fermentation in the large intestine by bacterial colonies. (cellulose beta bond, and starch alpha bond)
Fibre
The fraction of the edible part of the plant, or their extracts, or analogous carbohydrates that is resistant to digestion and absorption in the human intestine, usually with complete or partial fermentation in the large intestine by bacterial colonies. (cellulose beta bond, and starch alpha bond)
sources: cell walls on plants, seed coats (bran) of cereals, Structural components of fruit, nuts and vegetables, roots
vegetables Microbiological, fungal or animal components
(e.g. body shell and exoskeletons)
soluble fibre
(type of dietary fibre) Pectin, gum, mucilage and some hemicellulose
insoluble fibre
(source of dietary fibre) doesn’t change in the presence of water.
cellulose, hemicellulose and lignins
Galactose
diifers with glucose by orientation around the C4. converted to glucose in the liver ( by the enzyme galactokinase)
+ glucose= lactose
the least sweet monosaccharide
Galactocymia
reduction in the metabolism of galactose to glucose.
- deficiency in the enzyme galactokinase or other metabolic genes.
galactose build up leads to bacterial infections, mental retardation and cataracts.
must avoid foods that contain it
- milk products
- organ meats
- some fruit, nuts and veg.
Galactocymia
reduction in the metabolism of galactose to glucose.
- deficiency in the enzyme galactokinase or other metabolic genes.
galactose build up leads to bacterial infections, mental retardation and cataracts. Perceived early on in life.
must avoid foods that contain it
- milk products
- organ meats
- some fruit, nuts and veg.
Sugar alcohols
derivatives of mono, di or polysaccharides.
Class of polyols, 1 OH group attached to each carbon
Primarily used as low energy sweeteners because not fully
absorbed in small intestine. In the colon, fermented by
bacteria (produces gas)
May induce bloating, diarrhoea and flatulence with large
quantity as water is drawn into the colon, and bacterial
fermentation
Occur naturally in many fruit and vegetables (extracted from birch tree, corn cobs), but usually issued from hydrogenation of sugars (sorbitol, mannitol, xylitol), or via fermentation of sugars (erythritol) for commercial purposes
Xylitol, adonitol, Dulcitol.
Discuss the pros and cons alternative sweeteners that may replace sugar and caloric sweeteners
Artifitial sweetners they are much sweeter.
Pros: in context of type 2 diabetes and obesity: don’t contibute to blood sugar levels, don’t contribute to caloric intake
cons: consumed in excess may produce lots of gas, bloating, diarrhoea
Discuss the pros and cons alternative sweeteners that may replace sugar and caloric sweeteners
Artificial sweetners they are much sweeter.
Pros: in context of type 2 diabetes and obesity: don’t contribute to blood sugar levels, don’t contribute to caloric intake
cons: link b/w sweetners and promoting bad bacteria= bad gut microbiota= metabolic effects
psychological response: saving calories to eat more things.
Pentose monosaccharides
(makes supply via pentose phosphate
pathway)
ribose and deoxyribose
contain 5 Carbon
Are an essential part of the cells genetic material- ribose
(RNA) deoxyribose (DNA)
also found in food: nuts, meat, dairy, vegetables, and it is part of riboflavin
Lactose intolerance
Primary/ secondary
symptoms
solution
inability to digest lactose (dosage dependent)
primary: shortage of the enzyme lactase in adulthood because of the lactase non-persistence. which is the default post weaning.
secondary: in lactose persistent phenotypes (ethnicities and pop with farming ancestry) it is associated with damage of the lactase producing cells.
symptoms: Nausea, Cramps, distention, gas, diarrhoea
symptoms last 30min- 2 hrs post consumption.
solutions: take enzyme lactase
zygomil: has enzymes already in the milk to aid digestion
Amylose
all bonds between molecules are 1-4 alpha bonds. Alpha bonds= straight row.
continuous chain of glucose molecules
linked by α-1,4 glycosidic bonds
amylopectin
All bonds between molecules 1-4 alpha bonds, except where the molecule branches.
branched chain of glucose molecules linked by α-1,4 and α-1,6 glycosidic bonds. More quickly digested as more sites available to enzymes activity
