Lecture quiz 4/10/23 (monday) Flashcards
What are three elements that carbohydrates are composed of?
- carbon (C)
- hydrogen (H)
- oxygen (O)
Where does the word carbohydrate derive from?
- Carbo = Carbon
- Hydrate = Water H2O
What is ratio of C, H, and O
-1:2:1
example: C6H12O6
What is the main (function) nutritional purpose of carbohydrates?
supply energy
Where do most carbohydrates originate from?
plant sources
exceptions: glycogen and lactose
How much does CHO make up approx in a plant?
3/4 of the dry weight
Where are carbohydrates formed?
photosynthesis in plants
What is the primary source of carbohydrates in livestock feeds?
forages and grains
grain examples: oats, corn, barley, rice
forages example: fiber
- not suitable for those who cant digest fiber
example: ruminants/horses
What are the three classifications of carbohydrates?
- monosaccharides
- disaccharides
- polysaccharides
What are monosaccharides?
- composed of 1 sugar molecule
- characterized by how many carbon atoms they contain
+ most important and numerous contain 5 or 6 carbons
Pentose has how many carbons?
5
What are examples of pentoses?
- arabinose, xylose, and ribose
What is the most important pentose?
ribose because it can be found everywhere
why is ribose the most important pentose?
- found in every living cell
- occurs in compounds involved in metabolism
- ATP/ADP (energy transfer)
- Riboflavin (B-vitamin)
- DNA (genetic coding)
- RNA (protein synthesis)
Why don’t we need ribose in our diet?
bodies can synthesize ribose
What are examples of hexose?
- glucose
- fructose
- galactose
- mannose
*** 70% of honey is made out of fructose and semen has high levels of fructose
What is the most important hexose?
Glucose
Why is glucose the most important hexose?
- the primary form of sugar used for energy
- most complex carbohydrates contain glucose
- major end - product of CHO digestion for nonruminants
Exception: free form of glucose can be found in blood glucose
What are disaccharides?
composed of 2 monosaccharides
what are the most important disaccharides?
- sucrose (table sugar) = glucose + fructose (∂1,2 - glycosidic linkage)
- lactose (milk sugar) = galactose + glucose (ß 1,4 - glycosidic linkage)
- maltose (from germinating grain + need to make beer) = glucose + glucose (∂1,4 - glycosidic linkage)
What are polysaccharides?
sugar polymers
What are the 5 important polysaccharides?
starch, glycogen, beta-glucans, cellulose and hemicellulose
What is starch?
made out of repeating units of glucose connected with alpha-bonds.
What are the 2 important forms of starch?
Amylose and amylopectin
What is amylose?
- straight chain (unbranched)
- ∂1,4 linkage only
- 14-30% of total plant starch
- soluble in water
What is amylopectin?
- ∂1,4 lingake with ∂1,6 linkage at branch points
- 70-85% of total plant starch
- not soluble in water
- more digestible than amylose
What is the difference between amylose and amylopectin?
amylose
- unbranched helical chain
- harder to digest
amylopectin
- branched chain
-more open ends
- more places to break and easily digested
*** animals are fed mostly grain + rarely fed rice
potatoes have high in starch
waxy corn and potatoes have more amykopectin
- more energy for animals
- humans do not need these
What is glycogen (animal starch)?
- found in liver and muscle
- composed of highly branched chains of glucose (alpha linkage) which is store in animal cells (liver and muscle) for a ready supply of energy
- limited amount
- each glycogen granule has protein, glycogenin surrounded by branches of glucose units
** not a significant source of carbs
What are beta-glucans?
- minor polysaccharides that can be found at increased levels in barley and oat (4-5% of the dry weight)
- chains of glucose with ß 1,4 and ß 1,3 linkages
- absorbs water and forms a gel (once it reaches the intestines)
= reduces rate of passage (and feed consumption)
= reduces digestibilty of other nutrients and energy
= may cause sticky or wet feces in pigs and poultry
How are beta-glucans be broken down?
microbes in the digestive track
What enzyme do we give swine and poultry if barley is given to eat?
beta-glucanase
what is cellulose?
- made out of repeating units of glucose connected with beta bonds
- most abundant biomolecule on earth
- comprises 25-30% of fibrous plants (high in cell walls)
- can not be digested by mammalian or avian enzymes
- digested by microbial enzymes
What is the difference between starch and cellulose?
starch = glucose connected with alpha
cellulose = glucose connected with beta
what is the difference between alpha and beta linkages
alpha = OH is same side
beta = OH is opposite side
what is hemicellulose?
- just about like cellulose except all of the sugar units are not just glucose
- complex mix of glucose, xylose, mannose, arabinose and galactose with beta linkages
- principle component of plant cell walls
- degraded only by microbial enzymes
- hemicellulose and cellulose are 2 of the major CHO found in forages and roughage (pasture, hay, silage, straw and etc)
what is lignin?
lignin is NOT A CARBOHYDRATE
- it is associated with cellulose and hemicellulose in fibrous feeds
- encases cellulose and hemicellulose to enhance rigidity of the plant cell wall
- as plants mature they become woody due to lignification
- lignification reduced digestibitly by acting as barrier to the plant CHO
- no animal or bacterial enzymes can breakdown lignin (INDIGESTIBLE)
- when fibrous feeds are analyzed for nutrients, its also important to analyze lignin
What is the second most abundant biological material on the planet?
lignin because it is exceeded only by cellulose and comprises 15-25% of the dry weight of woody plants
What are components of the cell wall?
hemicellulose, cellulose and lignin
Cell walls make up a large portion of the forage (T/F)
true it is 40-80% of the dry weight
- the amount and composition cell wall is extremely important because it greatly influences forage quality
