EXAM 3 STUDY GUIDE

What do proteins serve as?

1. Structural elements of the body: Hair, wool, collagen (constituent of connective tissues)

2. Enzymes

3. Hormones

4. Carriers in the blood (hemoglobin)

5. Associated with genres the hereditary factors

6. Antibodies (In immunological defense mechanisms)

What percentage do proteins comprise of the dry, fat free body?

• 80%

What elements do proteins contain?

• C, H, O

• All proteins contain N (almost all proteins also contain S)

The average N content is taken as ___ for estimating the protein content of ___ and ____

• 16%

• Tissues and feedstuffs

An approximation of N content varies from ___ to ___

• 14 to 20%

TRUE OR FALSE?

The direct determination of protein in feeds or tissues would be practically impossible?

True

What percentage does feed protein contain of N?

• 16%

What does the analysis for protein determine?

• The nitrogen

What is the factor 6.25 used for?

• To calculate the protein content

What is the factor 6.25 determined by?

• Dividing 100% by 16%

FEED CP=

• Nx

MILK CP=

• Nx

What is the classification of proteins based on?

• Physical properties

What do simple proteins yield?

• Only Amino acids or their derivatives on hydrolysis

What does the simple protein group consist of?

• Albumins

• Globulins

• Albuminoids

• Histones

• Protamins

What are conjugated proteins?

• Simple proteins combined with a non protein radical

What are nucleoproteins?

• One or more protein molecules w/ nucleic acid

• High in germs of seed and in glandular tissue and liver

• Example: RNA

What are glycoproteins?

• Protein molecule and a substance containing a carbohydrate group

• For example; Mucin in saliva

What are phosphoproteins?

• Protein molecule and a P- containing substance other than a nucleic acid or lecithin

• E.g Lasein

What are metalloprotein?

• Protein molecules and a metal

• E.g cytochrome oxidase (cu), hemoglobin (fe)

What are lipoproteins?

• Protein molecule and a lipid

• E.g Vldl, cell membranes

What do derived proteins consist of?

• Altered and degraded products of naturally occurring proteins

How are derived proteins produced?

• By an action of heat, enzymes, or chemical agents

What are amino acids?

• The end products of protein digestion

What are amino acids commonly referred to as?

• The building blocks for the body’s protein

How many amino acids are there?

• There are about 25 different ones present in protein

What are amino acids released by?

• By hydrolysis by strong acids or bases and by the action of certain proteolytic enzymes

What primarily are the amino acids liberated from protein hydrolysates?

• a amino

• I.E the carboxyl and amino groups are attached to the same carbon atom

TRUE or FALSE?

The carboxyl and amino groups are attached to the same carbon atom?

True

What are the various a- amino acids that possess different r groups attached to?

• The a carbon

What does the usual classification of amino acids depend on?

• The number of acidic and basic groups that are present

TRUE OR FALSE?

Neutral amino acids contain one amino acid and one carboxyl group

True

What does the acidic amino acids have excess of?

• Carboxyl over amino groups

TRUE OR FALSE?

The basic amino acids possess an excess of basic groups?

• True

What are neutral amino acids?

• Aliphatic amino acids

What are some essential amino acids?

• Methionine

• Arginine

• Threonine

• Tryptophan

• Histidine

• Isoleucine

• Leucine

• Lysine

• Valine

• Phenylalanine

How can plants synthesize all the amino acids found in nature?

• By virtue of their capacity to utilize ammonia and their ability to fabricate the carbon structures corresponding to each of the amino acids

What are skeletons?

Carbon structures

TRUE OR FALSE

Mammals lack the ability to make about half of these carbon structures

True

What is the quantitive phase?

• The gross amount of amino acids present in feedstuff

What is the qualitative phase?

• The proper balance of essential amino acids to meet the animals need

What happens if a quality amino acid is digested to a lesser extent than the overall value?

• The quality of the protein is lowered accordingly

What happens if there is a marked lag in digestion amino acid?

• Protein quality is reduced due to the “time factor” for protein synthesis

Apparent Digestibility coefficient

(Nitrogen intake - Fecal nitrogen) / Nitrogen intake

True Digestibility coefficient

Nitrogen intake - [Fecal nitrogen - M fecal nitrogen]) / Nitrogen intake

What is MFN?

• Enzymes

• Sloughed cells

• Bacteria

Nitrogen retention

Nitrogen intake - (Fecal nitrogen + Urinary nitrogen)

What does biological value measure?

• How well the N absorbed is used; % of digestion N that is utilized