DS: Macromolecules Flashcards
What is the main source of energy in the diet?
Carbohydrates
How are carbohydrates used to provide energy for the body?
Carbohydrates are broken down into gluocse which is then converted into intermediates for ATP and energy production by a process called glycolysis.
What are the 3 monosaccharides of carbohydrates?
- Gluocse
- Fructose
- Galactose
What are the 3 disaccharides of carbohydrate?
- Sucrose
- Maltose
- Lactose
What are the monosaccharide units of sucrose?
Fructose + glucose
What are the monosaccharide units of maltose?
2 x glucose monomers
What are the monosaccharide units of lactose?
Glucose + Galactose
How are gluocse monomers linked together?
Gluocse mongers are linked together by alpha 1,4 glycosidic bonds to form polymer chains. These polymer chains can be linked by alpha 1,6 glycosidic bonds to form branched chains.
What are the 3 polysaccharides of carbohydrate?
- Amylose
- Amylopectin
- Glycogen
Describe the structure of amylose
Starch composed of long chains of glucose linked by alpha 1,4 glycosidic bonds
Describe the structure of amylopectin
Starch composed of branched polymer chains of glucose, containing both alpha 1,4 and alpha 1,6 glycosidic bonds.
Describe the structure and function of glycogen
Glycogen is composed of long chains fo glucose monomers, synthesised by the enzyme glycogen synthase. Important for the storage of excess glucose molecules when blood sugar levels are high.
Where is carbohydrate digestion initiated?
Carbohydrate digestion is initiated in the oral cavity by salivary amylase.
What is the role of salivary amylase?
Salivary amylase breaks down starch (and glycogen) into disaccharides (maltose) and trisaccharides (maltotriose) and limit dextrins by cleaving alpha glycosidic bonds between glucose molecules. Breakdown into smaller monomers helps aid in the uptake of carbohydrates by the small intestine for utilisation by the rest of the body
What are the 3 main macronutrients?
- Carbohydrates
- Lipids (fats)
- Protein
Why does the amount of carbohydrate digestion decrease between the oral cavity and the stomach?
Salivary amylase production is low. Carbohydrate digestion also ceases temporarily in the stomach as the pH is too low to activate salivary amylase, plus being a protein means the enzyme would be digested itself.
What happens to carbohydrates that are still present in the duodenum of the small intestine?
Remaining complex carbohydrates are broken down by pancreatic alpha-amylase (PAA) from the pancreases.
Why cant PAA breakdown amylopectin?
PAA cannot break bonds at ends of chains or at branch points
What is the role of brush border enzymes in the duodenum of the small intestine?
Complete the hydrolysis of complex carbohydrates to monosaccharide monomers so they are in a readily absorbable form to be taken up by intestinal (enterocyte) mucosal cells for distribution around the body
What are the brush border enzymes present in duodenum and what are their functions?
- Sucrase: sucrose to fructose + glucose
- Lactase: lactose to galactose + glucose
- Maltase: maltose to 2 x glucose monomers
- Glucomylase: amylose to gluocse
- Dextrinase: amylopectin and limit dextrins to glucose