Introduction to Carbohydrate Unit. 1. What is the predominant monosaccharide in carbohydrates?...

Introduction to Carbohydrate Unit

1. What is the predominant monosaccharide in carbohydrates?

•Glucose, also referred to as dextrose

#s 2-4

• “Di” = 2; two monosaccharide units•Oligo: 3-10 monosaccharide units• Poly: >10 monosaccharide units

#5 What is a common suffix for [specific] carbohydrates? List common carbohydrates

•-Ose•Saccharide: derived from the Greek sakchar, meaning sugar or sweetness

#5 Specific examples of carbohydrates

• Monosaccharides–Examples: glucose (C6H12O6), fructose, and galactose, ribose

• Disaccharides –Examples: sucrose, lactose, and maltose 

#5 Specific examples of Carbohydrates• Oligosaccharides: 3-10

sugars–Raffinose and stachyose

• Polysaccharides–Examples: starch, pectin, cellulose, and glycogen

• Sugar alcohols–Sorbitol, xylitol

#6 & #9: What is the name of the reaction by which di-, oligo-, and polysaccharides are formed? What is the name of the bonds between carbohydrates monomers?

• Dehydration synthesis/condensation

• (#9 )This type of rxn forms a glycosidic bond (C-O-C) also called glycosidic linkage–Two forms: alpha and beta

10. How do alpha and beta glycosidic bonds differ and how can this affect digestion?

• Alpha differs from the beta glycosidic bond only in the angle of formation between the two sugars

• Alpha-glycosidic linkage is below the plane of the rings and the beta glycosidic linkages are above

• Humans lack enzymes needed to cleave beta-glycosidic linkages – lactose intolerance

16. Why are oligosaccharides "gassy"?

• Can’t be broken down in small intestine and become “food” for bacteria of large intestine• Bacterial metabolism of

oligosaccharides results in gas byproducts

7. What is the name of the reaction by which di-, oligo-, and polysaccharides are broken down?

• Hydrolysis–The addition of a water molecule across a bond–The breaking down of a chemical compound into two or more simpler compounds by reacting with water.

• http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.html

#8 – Summarize the relationship between dehydration synthesis and hydrolysis

• They are reverse rxns, where one is a synthesis rxn and one is a break down rxn

Hydrolysis Dehydration Synthesis

Disaccharide + H20 MonoSach + MonoSach

• http://youtu.be/b7TdWLNhMtM

11. In your own words, describe how/why cyclic carbohydrates form.

12. How are carbohydrates found in humans classified?

• By number of carbons–Trisoses–Pentoses–Hexoses–Septoses….

5

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13. Carbs are also classified by their functional groups - what are the names of these classifications?• Aldoses – contain aldehyde

functional group– Terminal carbonyl C=O

• Ketoses – contain ketone functional group– Internal carbonylCarbonyl carbon

Carbonyl Carbon• In the closed-ring (cyclic) structure,

the carbonyl carbon is the one which is attached to the O of the ring and an OH group

14. Where can your body storage glucose?

• Liver as glycogen• Smaller amounts in muscles and brain as glycogen• Circulates in blood stream in very specific range

15. What are indigestible forms of polysaccharides known as?

• Dietary fiber

17. Explain the basic relationship between sugar and diabetes.

• Insulin: pancreatic hormone which signals cells to uptake glucose from blood (into cells)• People with Diabetes either do not produce insulin or do not respond to insulin that is present

18. How does the glycemic index classify carbohydrates?

•By how quickly and how high a specific carbohydrate boosts blood glucose levels compared to pure glucose

19. List food sources of carbohydrates

• Grains (breads, rice, pasta, cereal)• Fruit• Dairy• Beans, legumes• Soda, candy, etc.

20. List some functions of carbohydrates:

• Energy source for cells; primary for brain

• Protein sparing• Breakdown of fats and preventing

ketosis• Biological recognition• *Dietary fiber & digestive health• *Flavor and sweeteners