carbohydrates: background Flashcards
What is the general chemical formula for carbohydrates?
(CH 2O) x
Name three key functions of carbohydrates in the body.
Source of metabolic fuel and energy storage.
Structural components of plant cell walls.
Components of RNA, DNA, proteins, and lipids.
What are the three main monosaccharides, and where are they found?
Glucose: Found in fruits, plant juices, and honey.
Fructose: Found in honey and ripening fruits.
Galactose: Found in milk as part of lactose.
What determines whether a carbohydrate is digestible by mammalian enzymes?
The type of glycosidic bond (α or β).
What is the difference between glycaemic and non-glycaemic carbohydrates?
Glycaemic carbohydrates are digestible and raise blood glucose levels.
Non-glycaemic carbohydrates are not broken down by pancreatic or brush border enzymes.
What are the two types of polysaccharides, and what distinguishes them?
Glycaemic: Includes starch (amylose and amylopectin) and glycogen.
Non-glycaemic: Includes cellulose, hemicellulose, and pectins.
What are the recommended UK dietary intake percentages for carbohydrates?
Total carbohydrates: 50% of energy intake.
Free sugars: Less than 5% of energy intake.
Fibre: 30 g/day.
What are the key enzymes involved in carbohydrate digestion in the small intestine?
Pancreatic amylase and brush border enzymes.
How are monosaccharides transported across the small intestine wall?
Active transport: SGLT-1 for glucose and galactose.
Facilitated diffusion: GLUT transporters for fructose.
What happens to carbohydrates in the large intestine?
Non-digestible carbohydrates are fermented by gut microbiota, producing short-chain fatty acids and gases.
How is glucose stored in the body?
As glycogen in the liver and muscle tissues.
Why is fibre intake important for health?
Fibre improves bowel habits and reduces the risk of bowel cancer.
What is the role of glucose in metabolism?
Primary source of energy for cells.
Precursor for amino acid and fatty acid synthesis.
What are the potential effects of low carbohydrate intake?
Glycogen depletion and hypercholesterolemia.
What are free sugars, and why are they limited in the diet?
Free sugars include mono- and disaccharides added to foods and naturally present in honey and syrups.
High intake is linked to poor oral health.
