AN SC 260 - 4

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What are the functions of carbs?
- Major components of plant tissue
- Main energy source for most livestock
- Free CHO central to metabolism
What are some examples of monosaccarides?
- Glucose - hexose/dextrose
- Fructose
What is important about glucose?
- Ultimate source of E for most animal cells
- Central to metabolism
- No degradation needed for absorption
What are some examples of disaccharides?
- Sucrose
- Lactose
- Maltose
What does sucrase do and what is released?

Hydrolyzes sucrose

Glucose and fructose released
What is maltose a product of and where is it present?

Starch Digestion

Germinating Grain (beer production)
What are the bonds found in polysaccharides?

Alpha and Beta
What significance do alpha and beta bonds have?

Animals can break down alpha bonds but not beta bonds

Microbes in ruminants can break down beta bonds
What bonds are found in starch?

Amylose - alpha-1,4 linked glucoses

Amylopectin - alpha 1,4 linked glucoses with alpha-1,6 branches
Why is starch more soluble in hot water than in cold water?

Insoluble in cold water

When heated, water in starch will gelatinize which increases accessibility by enzymes
What happens amylose and amylopectin upon cooling after gelatinization?
- Amylose - re-crystalizes
- Amylopectin - gels
What are some properties of Cellulose?
- Unbranched chain of beta-1,4 linked glucoses
- Most abundant plant constiuent
What are some properties of hemicellulose?
- Branched
- More digestible than cellulose
- Acid releases arabinose side chains
What is lignin?
- Derived from wood
- Not a carb
- Repeating phenylpropane units
What are soluble fibres?
- Soluble non-starch polysaccharides
- beta-linked sugar molecules (indigestible by animals)
- beta-glucans
What is an example of a soluble fibre?

Arabinoxylans
What is starch broken down by and where?
- Amylase
- Mouth(saliva), Pancreas
What are the steps of starch breakdown?

Starch => dextrins => maltose => glucose
Where does most of absorption occur?

Small intestine - duodenum & jejunum (mostly beginning of jejunum)
How glucose transported across the membrane?
- Facilitated
- Sodium symport - 2 Na+ per 1 glucose
- Down [] gradient
What are the precursors for gluconeogenesis?
- AAs
- Lactic Acid
- Fat (glycerol, no net synth of glucose)
Why is it important to replenish glycogen stores?
- Reserves only stored in liver for 1/2 day
- Brain & red blood cells completely dependent on glucose for E
What are the steps of glycolysis and how many ATP are produced?
- Glucose => fructose 1,6 bisphosphate => pyruvate
- Net 8 ATP generated
- Pyruvate => 2 Acetyl CoA
- 6 ATP
- 2 Acetate => 2 CO2 + 2 H2O
- Net 24 ATP generated
TOTAL 38 ATP
What is the precursor for fat synth?

Acetyl CoA
What is ketosis?
- Not enough glucose in blood
- Fat metabolized for energy
- Ketones produced faster than can be metabolized
What is insulin-dependent diabetes mellitus (Type I) caused by?

Destruction of Islets of Langerhans in pancreas
What is non-insulin-dependent diabetes mellitus (Type II) caused by?
- Deficiency of cell-surface binding sites for normal glucose uptake
- Aggravated by obesity
What is the most important form of diabetes in domestic animals?

Gestational diabetes mellitus

Author

ebacker

177739

Card Set

AN SC 260 - 4

Description

Chapter 4 - Carbohydrates in Animal Nutrition

Updated

2012-10-15T18:50:10Z

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