Revision questions - week 4 Flashcards
digestible carbohydrates
can be digested and therefore provide energy
Indigestible cabrohydrates
(contain dietary fibre consisting of a group of complex carbohydrates (found mostly in veges, fruits and legumes) with a fibrous structure the makes them indigestible by humans so contribute no calories or energy to diet) don’t react in water
monosaccharides
simplest carbohydrate
- 6 carbon single units – glucose (carbonyl group on C-1, undergoes glycolysis or glycogenesis), fructose (carbonyl group on C-2, not insulin dependent) and galactose (OH group around C-4, converted to glucose in the liver)
- 5 carbon single unit – ribose and deoxyribose
screenshot of how they look
disaccharides
- Maltose – glucose to glucose, alpha 1,4 glycosidic bond, cereals
- Lactose – galactose to glucose, beta1,4 glycosidic bond, milk
- Sucrose – glucose to fructose, alpha 1,2 glycosidic bond, table sugar, fruit
polysaccharides
Starch – digestible, storage form of carbohydrate in plant,
- Amylose – continuous chain of glucose molecules linked alpha 1,4 glycosidic bonds, - lower GI because broken down more slowly
- Amylopectin – branched chain of glucose molecules linked by alpha 1,4 and alpha 1,6 glycosidic bonds, enzymes can come from every angle and therefore can break down quickly
Glycogen
- Storage form of glucose, branched structure containing 1,2 an d1,6 alpha glycosidic bonds
Cellulose
Why would fructose be considered a “good” sugar for diabetics?
Because blood sugar levels only measure glucose, this false though as turns to glucose inside the cell
What is high fructose corn syrup? How is it different to table sugar?
sweeter as proportion of fructose (55) to glucose (42)
are nutritionally the same
Why is it preferred by the food industry
??
Define how amylose, amylopectin and glycogen differ from each other in structures (bonds, and enzymes used to digest the structures) - will come back to after rewatching lecture
- Amylose – linked alpha 1,4 glycosidic bonds, broken down by salivary amylase
- Amylopectin – linked by alpha 1,4 (broken down by salivary amylase) and alpha 1,6 glycosidic bonds,
Glycogen
containing 1,4 (hydrolysed by both salivary & pancreatic
amylase) and 1,6 alpha glycosidic bonds (intestinal α-dextrinase)
Explain the concept of “carbohydrate quality” using the glycemic index and glycemic load
?
What determines the degree of fermentability of indigestible carbohydrates?
The solubility – more soluble more fermentation
Define dietary and functional fibre?
- Dietary fibre comes from food, functional fibre is added to food
- Men – 30g, women – 25g
- Endpoints chosen to estimate requirements were – adequate gastrointestinal function and adequate laxation rather than reduction of risk for chronic disease
How are carbohydrate foods involved in BGL?
glucose??
What are the mechanisms that regulate high and low blood sugar levels (BGL)?
??
insulin and glucagon??
How is the quality of carbohydrate in food determined, looking at the NIP?
NIP does not show quality? Can be rated by glycaemic quality, glycemic load, carbohydrate quality
Physiological function of fibre
- Promoting bowel health by increasing faecal bulk and laxation
- Reducing obesity and weight gain risk
- Assisting in blood glucose control
- Reducing plasma cholesterol
- promoting gut health and overall health
Promoting bowel health by increasing faecal bulk and laxation
- increases faecal bulk will increase the volume circulating in intestine which promotes peristalysis
- Prevention of diverticulae and diverticulosis/diverticulitis
Reducing obesity and weight gain risk
Assists in appetite control: feeling fuller because it slows down gastric emptying, thus less overeating
- more bulky so slows down as feeling of still full and less likely to over eat
Assisting in blood glucose control
Slowing down gastric emptying, therefore slowing down CHO digestion and glucose absorption and rise in BGL
- glucose absorbed quickly from sugar but when mixed with fibre takes longer for enzyme to access CHO to break down and enzymes will have longer time due to gastric emptying
Reducing plasma cholesterol
Promotes binding and excretion of cholesterol and bile,and thus prevents reabsorption of cholesterol (discussed when studying lipid)
- if consume cholesterol (we produce 80%) and have fibre you prevent dietary cholesterol as it tends to bind with cholesterol
Is honey a healthier option to table sugar? Why?
honey isnt a healthier option as contains same amount of CHO
What is meant by lactase persistence? What is the outcome?
means that one has a mutation in the region of this gene (genetic adaptation);
will elimate lactose intolerance
What is meant by alpha diversity in the context of the gut microbiota?
Healthy diversity = healthy gut microbiota (richness,variety and evenness in species)
How does diet promote health benefits through alpha diversity?
??
