Lecture quiz 4/10/23 (monday)

Question 1

What are three elements that carbohydrates are composed of?

Answer 1

• carbon (C)
• hydrogen (H)
• oxygen (O)

Question 2

Where does the word carbohydrate derive from?

Answer 2

• Carbo = Carbon
• Hydrate = Water H2O

Question 3

What is ratio of C, H, and O

Answer 3

-1:2:1

example: C6H12O6

Question 4

What is the main (function) nutritional purpose of carbohydrates?

Answer 4

supply energy

Question 5

Where do most carbohydrates originate from?

Answer 5

plant sources

exceptions: glycogen and lactose

Question 6

How much does CHO make up approx in a plant?

Answer 6

3/4 of the dry weight

Question 7

Where are carbohydrates formed?

Answer 7

photosynthesis in plants

Question 8

What is the primary source of carbohydrates in livestock feeds?

Answer 8

forages and grains

grain examples: oats, corn, barley, rice
forages example: fiber
- not suitable for those who cant digest fiber
example: ruminants/horses

Question 9

What are the three classifications of carbohydrates?

Answer 9

• monosaccharides
• disaccharides
• polysaccharides

Question 10

What are monosaccharides?

Answer 10

• composed of 1 sugar molecule
• characterized by how many carbon atoms they contain
  + most important and numerous contain 5 or 6 carbons

Question 11

Pentose has how many carbons?

Answer 11

5

Question 12

What are examples of pentoses?

Answer 12

• arabinose, xylose, and ribose

Question 13

What is the most important pentose?

Answer 13

ribose because it can be found everywhere

Question 14

why is ribose the most important pentose?

Answer 14

• found in every living cell
• occurs in compounds involved in metabolism
  
  • ATP/ADP (energy transfer)
  • Riboflavin (B-vitamin)
  • DNA (genetic coding)
  • RNA (protein synthesis)

Question 15

Why don’t we need ribose in our diet?

Answer 15

bodies can synthesize ribose

Question 16

What are examples of hexose?

Answer 16

• glucose
• fructose
• galactose
• mannose

*** 70% of honey is made out of fructose and semen has high levels of fructose

Question 17

What is the most important hexose?

Answer 17

Glucose

Question 18

Why is glucose the most important hexose?

Answer 18

• 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

Question 19

What are disaccharides?

Answer 19

composed of 2 monosaccharides

Question 20

what are the most important disaccharides?

Answer 20

• 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)

Question 21

What are polysaccharides?

Answer 21

sugar polymers

Question 22

What are the 5 important polysaccharides?

Answer 22

starch, glycogen, beta-glucans, cellulose and hemicellulose

Question 23

What is starch?

Answer 23

made out of repeating units of glucose connected with alpha-bonds.

Question 24

What are the 2 important forms of starch?

Answer 24

Amylose and amylopectin

Question 25

What is amylose?

Answer 25

- straight chain (unbranched) - ∂1,4 linkage only - 14-30% of total plant starch - soluble in water

Question 26

What is amylopectin?

Answer 26

- ∂1,4 lingake with ∂1,6 linkage at branch points - 70-85% of total plant starch - not soluble in water - more digestible than amylose

Question 27

What is the difference between amylose and amylopectin?

Answer 27

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

Question 28

What is glycogen (animal starch)?

Answer 28

- 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

Question 29

What are beta-glucans?

Answer 29

- 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

Question 30

How are beta-glucans be broken down?

Answer 30

microbes in the digestive track

Question 31

What enzyme do we give swine and poultry if barley is given to eat?

Answer 31

beta-glucanase

Question 32

what is cellulose?

Answer 32

- 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

Question 33

What is the difference between starch and cellulose?

Answer 33

starch = glucose connected with alpha cellulose = glucose connected with beta

Question 34

what is the difference between alpha and beta linkages

Answer 34

alpha = OH is same side beta = OH is opposite side

Question 35

what is hemicellulose?

Answer 35

- 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)

Question 36

what is lignin?

Answer 36

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

Question 37

What is the second most abundant biological material on the planet?

Answer 37

lignin because it is exceeded only by cellulose and comprises 15-25% of the dry weight of woody plants

Question 38

What are components of the cell wall?

Answer 38

hemicellulose, cellulose and lignin

Question 39

Cell walls make up a large portion of the forage (T/F)

Answer 39

true it is 40-80% of the dry weight - the amount and composition cell wall is extremely important because it greatly influences forage quality