Nutrients & their Metabolism Flashcards
What are the important dietary CHO categorised into?
Monosaccharides
Disaccharides + oligosaccharides
Polysaccharides
How many carbons can monosaccharides have?
3 to 7
What are the most important monosaccharides?
The 6C hexoses:
- Glucose
- Galactose
- Fructose
What is the most important monosaccharide
alpha-D-glucose
What is the sweetest monosaccharide?
Fructose
How is high fructose corn syrup manufactured enzymatically?
By changing the glucose in cornstarch to fructose.
What does evidence suggest about high fructose corn syrup?
That high diets of this may contribute to obesity + other health conditions i.e metabolic syndrome.
Where are galactose + fructose metabolised?
Liver
What do infants have when they are born with inability to metabolise galactose?
Galactosemia
What are the 3 most important disaccharides
Sucrose
Lactose
Maltose
How are disaccharides formed?
By glycosidic linked monosaccharides between the active aldehyde or ketone carbon + a specific hydroxyl on another sugar.
Describe what an invert sugar is
A natural form of sugar
An unlinked glucose + fructose in a 1:1 ratio
Why is invert sugar used commercially?
Sweeter than the equal conc. of sucrose.
Give an example of an invert sugar
Honey
What are oligosaccharides
Small 3-10 monosaccharide
Readily H20 soluble
Often sweet
Define a polysaccharide
CHO w/ 10+ monosaccharide units
Why is amylopectin more abundant in the food supply than amylose?
Due to its larger size
What causes different starches to have their own unique taste, texture + absorbability?
The rel. no. of glucose units in straight (amylase) and branched configurations (amylopectin)
+
The degree of accessibility to digestive enzymes.
What does moist cooking cause for the starch granules?
Causes them to swell
= Gelatinises the starch, softens + ruptures the cell wall
= Making starch more digestible by pancreatic amylase.
Define dietary fibre
Intact plant components
GI enzymes can’t digest
Define functional fibres
Nondigestible CHO that have been extracted or manufactured from plants
List some of the less soluble fibres
Cellulose
Hemicellulose
Lignin
Major function of cellulose as a less soluble fibre
⬆️ H20-holding capacity = ⬆️ fecal volume + ⬇️ gut transit time.
Major function of lignin as a less soluble fibre
Fermentation produces short-chain FAs associated w/ ⬇️ risk of tumor formation
List some of the more soluble fibres
Gums
Pectins
Major function of gums being a more soluble fibre
Cause gel formation = ⬇️ gastric emptying, slow digestion = slow gut transit time + glucose absorption
Major function of pectins as a more soluble fibre
Binds minerals, lipids + bile acid = ⬆️ excretion of each = ⬇️ serum cholesterol
What is the major function of the more functional fibre Fructans
Prebiotic that stimulates growth of beneficial bacteria in gut
Used as a fat replacer
Approx what % of the human diet do fats + lipids constitute?
34%
Where is dietary fat stored in the human body?
Adipose cells
What is structural fat?
Fat deposits that aren’t used effectively during a fast.
What type of fat holds the body organs + nerves in position and why?
Structural fat pads
To protect them vs traumatic injury + shock.
What do structural fat pads on the palms + buttocks do?
Protect the bones from mechanical pressure
What is dietary fat essential for?
The digestion, absorption + transport of fat-soluble vitamins + phytochemicals.
Depresses gastric secretions
Slows gastric emptying
Stimulates biliary + pancreatic flow
== Facilitating digestion
Give some examples of photochemicals
Carotenoids
Lycopenes
Length of chains + number of bonds for the fats that are liquid at room temp
Shorter chains
More double bonds
Solid at room temp fats?
Sat fats
Long chained
What type of fat is coconut oil
A highly saturated fat
What state is coconut oil in at room temp?
Why?
Semiliquid
Due to the predominant FA being short (8-14C).
Binding sites on a sat FA
All C binding sites nOT linked to another C are linked to H
+ are therefore saturated.
How many double bonds do monounsaturated FA have?
1
How many double bonds do polunsat FA have?
2 or +
Describe the omega notation convention used to describe the location of double bonds
Lower case omega (w) or n is used to refer to the placement of the 1st double bond counting from the METHYL end.
What can only plants synthesise?
Omega-6 FA
Omega-3 FA
What are aa
Carboxylic acids w/ an amino group attached to the alpha-C
Negative effects of alcohol
Depression
Gi tract irritant
Foetal development issues
Weightgain
By which method is vitamin C absorbed?
Active transport
Where is vitamin c stored?
Pituitary + adrenal glands
WBC
Eyes
Brain
What can vitamin D to phosphorus?
⬆️ its absorption
Where is vitamin E stored?
Adipose tissue
