Intro to Biochem

Question 1

What are the three main components of feedstuffs?

Answer 1

Carbohydrates, proteins and fats

Question 2

Define CARBOHYDRATES

Answer 2

A carbohydrate is a group of substances used as both energy sources and structural materials in organisms. All carbohydrates contain carbon, hydrogen and oxygen.
General formula:
Cn(H2O)n

Question 3

What are the three main groups of carbohydrates?

Answer 3

Monosaccharides (simple sugars)
Disaccharides (double sugars, formed of two monosaccharides)
Polysaccharides (large molecules formed of many monosaccharides)

Question 4

Define GLUCOSE

Answer 4

A monosaccharide. It is the major energy source for most cells.. Highly soluble and the main form in which carbohydrates are transported around the body.
Two types: alpha and beta

Question 5

Define FRUCTOSE

Answer 5

A monosaccharide. The second most important one after glucose.

Question 6

Define MONOSACCARIDES

Answer 6

A monosaccharide is the simplest type of carbohydrate. Can serve alone or as part of a larger structure (di or polysaccharides)
Molecular formula: CH2O
Examples: glucose, fructose

Question 7

Define DISACCHARIDES

Answer 7

A disaccharide is a double sugar, formed of two monosaccharides joined by dehydration synthesis.
The stronger the link between the two single units, the harder it is to break down/digest.
Examples: lactose, sucrose, maltose

Question 8

Define POLYSACCHARIDES

Answer 8

A polysaccharide is a polymer of up to one thousnad monosaccharide molecules, formed by dehydration reactions.
Examples: storage; starch and glycogen
structural; cellulose

Question 9

Define RESPIRATION

Answer 9

Respiration is the process of converting stored energy. The bonds in glucose are broken down the form carbon dioxide and water. The break down of glucose occurs in steps and each step is driven by enzymes. Plants and animals are only able to break down alpha glucose, and therefore it is the one used in respiration.

Question 10

Define GLYCOGEN

Answer 10

Glycogen is an extensive branched glucose storage molecule found in the muscle and liver of animals. Broken down more rapidly than starch.

Question 11

What is cellulose? How is it broken down in the horse?

Answer 11

Celluose is a polysaccharide that is the main component of plant cell walls. Contains long chains of beta glucose molecules. Cannot be broken down by the horse - instead it is broken down by microbiota in the caecum that are able to produce cellulase.

Question 12

What is the general structure of an amino acid?

Answer 12

• a basic amino group
• an acidic carboxyl group
• organic R group

Question 13

How many natural amino acids are there?

Answer 13

20 natural amino acids

Question 14

Define an INDISPENSIBLE AMINO ACID

Answer 14

An indispensable amino acid is one that cannot be synthesised from scratch and therefore must be supplied in its diet.

Question 15

Name the 3 key amino acids and describe them

Answer 15

• lysine - promotes bone growth in foals and enhances growth and nitrogen balance. Often in shortest supply in horse feeds.
• phenylalanine - produces both adrenaline and noradrenaline. It is an antidepressant.
• valine - regulates protein turnover and energy metabolism. Vital for muscle coordination

Question 16

Define DEAMINATION

Answer 16

Deamination is the removal of the amine group in the liver, as the horse cannot store excess amino acids. Too much protein = too much excretion.

Question 17

Define POLYPEPTIDES

Answer 17

Polypeptides are long chains of many amino acids linked together by peptide bonds.

Question 18

Define PROTEASES

Answer 18

Proteases are enzymes that catalyse the reaction that breaks down peptide bonds. An example is trypsin.

Question 19

Define LIPIDS

Answer 19

Lipids are fats. They are an excellent energy reserve due to many carbon-hydrogen bonds.

Question 20

What is the composition of a fatty acid?

Answer 20

• have a carboxyl group at one end
• rest of the molecule is a hydrocarbon
• the hydrocarbon chain can be anywhere from 15-18 carbons long
• they may be saturated (no double bonds) or unsaturated (double bonds)

Question 21

How are fats used in respiration?

Answer 21

• first comes the hydrolysis of the ester bonds holding the fatty acid and the glycerol together
• this hydrolyses the lipid to its glycerol and fatty acid components
• releases energy which is used to generate ATP

Question 22

What is formed when alpha glucose molecules join together?

Answer 22

They form long, coiled chains. Amylose is formed from chains of alpha glucose.

Question 23

What is formed when beta glucose molecules join together?

Answer 23

They form long, straight chains, used in the structural roles of plants. Cellulose is formed from chains of beta glucose.

Question 24

Define AMINO ACIDS

Answer 24

An amino acid is an organic molecule possessing both carboxyl and amino groups. Amino acids are the monomers of proteins. May be positively or negatively charged and may be hydrophilic or hydrophobic.