Topic 4: Carbohydrates classification and digestion
3. Nutritionally what are carbohydrates classified as?
- Fibrous or structural carbohydrates - Non-fibrous or non-structural carbohydrates
9. In what form is energy from carbohydrate digestion stored in the muscle?
- Glycogen o Also stored in the liver o Used as an immediate energy source - "fight or flight" response
5. What is meant by an enantiomer or isomer?
- Same chemical structure but mirror image - Often different chemical reactions - one form may be active while the other lesser or inactive - L- and D- isomers - Dependent on the orientation of the hydroxyl group on the penultimate C atom
2. What are carbohydrates chemically classified as?
- Sugar - Non-sugar
6. Cellulose is a polymer of which structure (and monosaccharide)?
β-D glucose
4. What is the main difference between fibrous and non-fibrous carbohydrates?
Fibrous contain structural components of plant - unable to be digested by animal enzymes o Able to be digested by microbes (foregut and hindgut fermenters) Non-fibrous contain plant cell contents - easy to digest o Include monosaccharides, disaccharides, starch
1. Discuss why the diet of ruminants is generally high in polyunsaturated fatty acids, and yet ruminant meat and milk are generally low in polyunsaturated fatty acids and high in saturated fatty acids.
*no answer*
15. How are sugars and starches digested and absorbed in the monogastric animal?
- Amylases break down bonds between sugar molecules to reduce polysaccharides to disaccharides - Transported across the luminal wall as disaccharides - Converted into monosaccharides (glucose, galactose, or fructose) by brush border enzymes - Transferred to vascular system
8. Starch is mostly made up of.....
- Amylose - Amylopectin
14. Which is more digestible - cellulose or lignin?
- Cellulose o Lignin is effectively indigestible - Decreases digestibility by rendering the carbohydrates inaccessible, even to the microbes
10. How else can energy from carbohydrate digestion be stored in the body?
Fats
13. Which is the more digestible - cellulose or hemicellulose?
Hemicellulose
11. Is lignin a carbohydrate?
No, but discussed within this category because of its association with carbohydrates in the plant cell wall.
12. Are glycosides generally useful in animal diets?
No, many are toxic, for example cardiac glycosides and cyanogenic glycosides
Which of the following is not a glucan? a) Starch. b) Cellulose. c) Glycogen. d) Fructan.
d) Fructan.
Which of the following statements is correct? a) Diets containing high levels of roughage (fibre) promote acetate production. b) Diets containing high levels of roughage (fibre) promote propionate production. c) Diets containing high levels of water soluble carbohydrates promote acetate production. d) Diets containing high levels of starch promote acetate production
a) Diets containing high levels of roughage (fibre) promote acetate production.
Which of the following is not classified as a non-sugar? a) Disaccharides. b) Heteroglycans. c) Complex carbohydrates. d) Glycolipids.
a) Disaccharides.
Which of the following statements is correct? a) Starch is the main storage carbohydrate in plants. b) Glycogen is the main storage carbohydrate in plants. c) Both starch and cellulose are fructose based structural carbohydrates. d) Fructans are commonly found in both temperate and tropical grass species.
a) Starch is the main storage carbohydrate in plants.
Polysaccharides are polymers of monosaccharide units. a) True. b) False
a) True.
Structural carbohydrates include a) cellulose, hemicellulose and lignin. b) cellulose, starch and lignin. c) cellulose, starch and glycogen. d) cellulose, glycogen and lignin.
a) cellulose, hemicellulose and lignin.
Glucose is a a) hexose. b) pentose. c) disaccharide. d) homoglycan
a) hexose.
The major end-products of microbial fermentation in the rumen are a) volatile fatty acids, methane and carbon dioxide. b) volatile fatty acids, methane and ammonia. c) volatile fatty acids, ammonia and carbon dioxide. d) volatile fatty acids, methane and carbon monoxide.
a) volatile fatty acids, methane and carbon dioxide.
All plants containing glycosides (monosaccharide derivatives) can be safely fed to livestock. a) True. b) False
b) False
Hemicellulose is a homoglycan. a) True. b) False
b) False
The majority of non-fibrous carbohydrates are digested in the small intestines of monogastric animals. a) True. b) False.
b) False
Increases in the acetate: propionate ratio increase both the efficiency of metabolisable energy (ME) use and microbial protein production. a) True. b) False.
b) False.
Lignin is readily fermented by rumen microbes. a) True b) False.
b) False.
The majority of non-fibrous carbohydrates are digested in the small intestine of ruminants. a) True. b) False.
b) False.
Which of the following is not a disaccharide? a) Lactose. b) Fructose. c) Maltose. d) Cellobiose.
b) Fructose.
Sucrose is a a) monosaccharide. b) disaccharide. c) polysaccharide. d) triose.
b) disaccharide.
Starch is a e) hexose. f) pentose. g) disaccharide. h) homoglycan.
h) homoglycan.
7. Starch (and glycogen) is a polymer of what structure (and monosaccharide)?
α-D glucose
