Study Unit 2 (II)

Question 1

What is a protein?

Answer 1

A protein is a polypeptide chain with more than 50 amino acids

Question 2

What are conjugated proteins?

Answer 2

Proteins that contain prosthetic groups

Question 3

What are the purpose of prosthetic groups like organic and non-organic components?

Answer 3

They determine the catalytic activity of proteins

Question 4

Example of a conjugated proteins

Answer 4

Haemoglobin

Question 5

Primary structure of proteins

Answer 5

Specific sequence of amino acids as specified by the gene, held together by covalent/peptide bonds

Question 6

Secondary structure of proteins

Answer 6

Portions of the structure begin to fold in unique 3D formations due to hydrogen bonds forming between the main chain peptide groups of the same polypeptide chain

Question 7

Tertiary structure of proteins

Answer 7

Formed by interactions of side chains of various amino acids. Some proteins are complete here

Question 8

Quaternary structure of proteins

Answer 8

Proteins incorporate multiple polypeptide subunits (more than one amino acid chain is present in this chain)

Question 9

In what is the mass of proteins determined?

Answer 9

Daltons

1 Dalton = mass of 1 hydrogen atom

Question 10

What do carbohydrates consist of?

Answer 10

Carbon, Hydrogen and Oxygen

Question 11

How are carbohydrates produced?

Answer 11

During photosynthesis in plants, in the form of mono- and polysaccharides. Light energy is converted to sugars by using CO2 and water.

Question 12

Examples of monosaccharides

Answer 12

Hexose (6 carbons)
- Glucose, Fructose, Galactose
Pentose (5 carbons)
- Arabinose, Ribose, Xylose

Question 13

Examples of disaccharides

Answer 13

Maltose
Sucrose
Lactose

Question 14

Examples of polysaccharides

Answer 14

Amylose
Amylopectin
Starch (consists of amylose and amylopectin)
Cellulose
Hemicellulose
Glycogen (stores energy in animals and fungi)

Question 15

What are lipids responsible for?

Answer 15

Lipids are responsible for energy storing in cells and also act as structural components of cell membranes

Question 16

What are fats?

Answer 16

Esters of fatty acids and glycerol that are soluble in organic solvents and insoluble in water.

Question 17

What are steroids?

Answer 17

Microbes with enzymes that mediate specific hydroxylations or dehydrogenations

Question 18

What is cholesterol?

Answer 18

A steroid that is produced in the liver and that is required to build and maintain membranes

Question 19

What is cortisone?

Answer 19

Cortisone is released during stress and suppresses the immune system

Question 20

What is transesterification?

Answer 20

Transesterification is the process of exchanging the organic group of an ester with the organic group of an alcohol

Question 21

What is biodiesel?

Answer 21

It is a fuel that consists of mono-alkyl esters of long-chain fatty acids derived from plant oils and animal fat

Question 22

Through which process is biodiesel produced?

Answer 22

Transesterification

Question 23

Sources of biodiesel

Answer 23

Plant oils
- Soy
- Canola
- Palm oil
- Tallow
- Lard
Waste oils
- Restaurant oil
- Old lubricating oil

Question 24

How is biodiesel obtained from these oils?

Answer 24

All these oils and fats consist mainly of triglycerides so the esters are thus obtained from them

Question 25

What are triglycerides?

Answer 25

Esters that consist of 3 fatty acids and glycerol

Question 26

Name and elaborate slightly on the process by which biodiesel is produced

Answer 26

During transesterification, the oil that contains esters reacts with alcohol

Question 27

How is biodiesel produced?

Answer 27

1. Free fatty acids are removed prior to the addition of a transesterification catalyst (NaOH, POH). (Leftover concentration of ffa should not be more than 5%)
2. During transesterification, the oil that contains esters reacts with alcohol (mainly methanol) to produce different esters.
   oil (Ester) + alcohol = esters (biodiesel) + glycerol (alcohol)
3. Separation of the resulting biodiesel and glycerol takes place in a separation funnel with the less dense biodiesel on top and the mostly dense glycerol at the bottom.

Question 28

How is it possible to separate biodiesel and glycerol?

Answer 28

Glycerol is an alcohol and alcohols are polar.
Biodiesel is nonpolar.
These products will thus not mix.

Question 29

Why do free fatty acids need to be removed before transesterification?

Answer 29

To prevent soap formation

Question 30

If there is a high concentration of free fatty acids in the feed (above 5%) how can biodiesel still be produced?

Answer 30

Through the esterification of the free fatty acids with an acid as catalyst. Transesterification of the ffa and an alcohol then produces biodiesel and water. The problem with this is that water formation then takes place, which formed the ffa in the first place. Heat is required to remove that water again.

Question 31

What are nucleotides?

Answer 31

They are the building blocks of RNA and DNA.

Question 32

What do nucleotides consist of?

Answer 32

Nucleobase
Sugar (ribose or deoxyribose)
Phosphate
Basis

Question 33

RNA vs DNA

Answer 33

DNA is double stranded whilst RNA is single stranded.
DNA is longer than RNA.
RNA consists of hundreds of bases whilst DNA can have 3 billion bases.

Question 34

Why should a cell’s composition differ from its environment?

Answer 34

If a living cell reaches thermodynamic equilibrium it will die. Energy must be consumed to avoid thermodynamic equilibrium.