Topic 3 Flashcards
What are the functions of glucose?
- Converted to glycogen to store energy
- Converted to fat to store energy (long term)
- Oxidized for energy
- Glycoproteins
- Precursor of amino acids C-skeleton
- Prevent ketosis
Which tissues/ organs/ processes use glucose for energy?
o Brain, RBCs, mammary gland, fetus, spermatogenesis
Describe glycoproteins
o Spontaneous glycation of proteins doesn’t require an enzyme and can damage the function of protein due to agedisturbs the function
o Some proteins have glucose attached to it that need it to function
The intestine does not need glucose, but uses __ as a fuel.
The intestine does not need glucose, but uses glutamate as a fuel.
WHich cells have an absolute requirement for glucose and why?
• Certain cells have an absolute requirement for glucose, such as the brain and RBCs which do not have any organelles. Therefore, their only source of energy is glucose and glycolysis
What an exception from the rule that glucose is a precursor for glucose?
o All of the amino acids that we can make in the body come from glucose EXCEPT for tyrosine (made from phenylalanine which is hydroxylated).
Phenylalanine+ OH-> Tyrosine
What is the recommended intake of CHOs?
45-65% of energy intake (1/2-2/3 of our intake)
Does glycogen make up a significant part of our diet?
no
Why should pregnant women not do keto diet?
GLucose is a major energy source for the fetus
Brain needs a __ supply of glucose
Brain needs a constant supply of glucose
WHat is the formula for CHO monomer?
Cn(H2O)n
Give an example of CHO monomer and it’s weight and formula
Hexoses-> C6H12O6 (FW: 180g)
What are the 2 types of bonds in disaccharides?
• Alpha or beta glycosidic bonds
o When Hydrogens on same side-> alpha
o When H on opposite sides, or the bond looks diagonal-> beta
List lactose, sucrose, glucose, maltose, fructose in terms of sweetness
o Fructose (twice as sweet as sucrose) (mono) o Sucrose o Glucose (mono_ o Maltose o Lactose
How do CHOs act as preservatives?
Presence of free sugar ties up free water an minimizes bacterial growth-> preservative
Name 2 types of starch units and their bonding
- Amylose alpha (1-4) chains
* Amylopectin alpha (1-4) chains with alpha (1-6) brancheы
Name 3 types of fibers, their examples and where they are found
Soluble
o Pectin (found in fruits)
o E.g. oatmeal
Insoluble
o Hemicellulose, cellulose
o E.g. celery
Functional
o Has characteristics of both soluble and insoluble fibre
o Psyllium added to foods—such as cereals to increase fiber intake
o Added as a food additive in processing, related to health-promoting effects
Metabolic effects of soluble fiber
- Forms viscous el in the stomach
- Delays gastric emptying-> CHOs are distributed more equally-> slower digested and absorbed
- Binds cholesterol and bile acids
- Fermented by colonic microbiota -> produces organic acids
Metabolic effects of insoluble fiber
- Bulk (laxative effect) - - Colon is not going to absorb as much water-> softens stool
- Delays gastric emptying->
Some glycemic control, but less than soluble fiber
o Binds cations (phytates are negative and will bind cations such as calcium, zinc, iron-> not desirable due to deficiencies that may arise)
o Speeds up transit altogether
o Minor fermentation by colonic bacteria
Which bonds does salivary amylase break?
the alpha, 1-4 bonds in starch
What is the pH of the stomach
-1
What is the level of glucose in blood?
usually 5 mmol/L
4g in our blood at any time
Hypoglycemia- what are the conditions and effects on the brain
blood glucose below 4g-? around 2g in the brain- > very low
Hyperglycemia- characteristic
consequences
10 mmol/L
Dehydration- water is excreted
