Intro to bioengineering

Question 1

What are the factors which affect growth of micro-organisms?

Answer 1

FAT TOM:
F ood
A cidity (conc.)
T emp.
T ime
O xygen
M oisture
also:
-Sources of carbon
-Electron acceptors

Question 2

How do Bacteria grow?

Answer 2

• Can grow to high concentrations, 100kgm^-3
• Growth rate can be extremely rapid (around 20minutes to double)

-Dependent on adequate transfer of nutrients, products and heat

Question 3

How do fungi (yeasts) grow?

Answer 3

• Yeasts grow in colonies of single cells (oblate shaped)
• Many can grow in the absence of oxygen, anaerobic (facultative w.t.r to oxygen)
• Larger in size than bacteria (2-12micrometers)
• Can grow to high cell concentrations, 100kgm^-3
• Grow slightly more slowly than bacteria (1.2hours min. to double)

Question 4

Give an example of a bioprocess that is anaerobic and one that is aerobic

Answer 4

• Anaerobic, production of alcohol with yeast (fermentation)

- Aerobic, production of yeasts for baking

Question 5

What is the equation for alcohol fermentation?

Answer 5

C6H12O6 + 2ADP -> 2CH3CH2OH + 2CO2 + 2ATP

Question 6

How do fungi (mushrooms) grow?

Answer 6

• Grow as highly branched networks of microbes (hyphae) to form mycelium
• Can become very dense in volume when grown in suspended cultures
• Can make the culture very thick, high viscosity
• Fairly slow growth, 3-4hrs min to double
• Only aerobic

Question 7

How do animal cells grow?

Answer 7

• Difficult to grow
• Large, 12-20micrometers
• Fragile
• Complex nutrient requirements
• Slow growth, 12-25h min to double
• Highly susceptible to contamination by faster growing fungi and bacteria

Question 8

How do plant cells grow?

Answer 8

• Very large, 20-150 micrometers
• Delicate, although do have cell walls
• Slow growing
• Difficult to maintain in pure cultures

Question 9

What is the effect of temp. on proteins and on lipid-containing membranes of cells and organelles?

Answer 9

Proteins: high temp. denatures protein

Lipid membranes:

• too low, membranes become rigid and fragile
• too high, membranes become too fluid and can’t contain cell or organelle

Question 10

From the following microorganisms which works at the coolest, and which at the warmest temp.?

mesophiles, psychrotrophs, thermophiles, hyperthermophiles, psychrophiles

Answer 10

psychrophiles < psychrotrophs < mesophiles < thermophiles < hyperthermophiles

Question 11

What range do most organisms have pH optima in? and which can very few species grow in?

Answer 11

pH 5-9 is optima for most

Below 2 or above 10 is difficult for most to grow in

Question 12

For microbial nutrition what do macronutrients do, give some examples?

Answer 12

• Required in large quantities
• Play principal roles in cell structure & metabolism

e.g proteins, carbohydrates

Question 13

For microbial nutrition what do micronutrients do and give some examples?

Answer 13

• Required in small amounts
• Involved in enzyme function and maintenance of protein structure

e.g manganese, zinc, nickel

Question 14

What is the chemical composition of cytoplasm?

Answer 14

• 70% water
• Proteins
• 96% of cell is composed from carbon, hydrogen, oxygen, phosphorus and sulphur

Question 15

What are heterotrophic organisms?

Answer 15

-Organisms which use organic chemicals as a carbon source

Question 16

What are lithotrophic organisms?

Answer 16

Organisms which use inorganic chemicals as a source of carbon

Question 17

What is the need for water in cells?

Answer 17

• Essential for growth and maintenance
• Serves as a transport medium, uptake of substrates, nutrients and release of metabolic products, and is an electron acceptor
• Too little moisture results in loss of acitivity
• Too much moisture reduces gas transfer

Question 18

What is catabolism and examples?

Answer 18

• Reactions where larger molecules break down into smaller ones
• Energy yielding
• Examples: breakdown of carbohydrates, proteins and lipids

-Catabolic reactions results in formation of ATP

Question 19

What is anabolism and examples?

Answer 19

• Reactions where larger molecules are made from smaller molecules
• Energy requiring
• Biosynthetic pathways
• Examples: synthesis of proteins and construction of phospholipids

-Driven by the Gibbs energy released by hydrolysis of ATP to form ADP or AMP

Question 20

What types of work do cells use internal energy e.g ATP to do?

Answer 20

• Chemical synthesis of large or complex molecules, growth
• Transport of ionic and neutral substance into or out of cells (endocytosis and exocytosis)
• Mechanical work required for cell division and motion

Question 21

How are energy requirements within cells met?

Answer 21

-By transferring electrons from substrate to electron acceptor

• Substrate is oxidised
• Electron acceptation is reduced
• Mediated through the action of enzymes

Question 22

In terms of electron acceptors what is the difference between aerobic and anaerobic processes?

Answer 22

-Aerobic, oxygen=electron acceptor
Substrate + O2 -> biomass + CO2 + H2O + organics

-Anaerobic, other chemical=electron acceptor
Substrate + H2 -> biomass + CH4 + organics

Question 23

What are aerobes?

Answer 23

Micro-organisms that can extract energy from compounds ONLY in the PRESENCE of oxygen

Question 24

What are anaerobes?

Answer 24

Micro-organisms that can extract energy from compounds ONLY in the ABSENCE of oxygen

Question 25

What are primary metabolites and give some examples?

Answer 25

• Small molecules of living cells
• Intermediates or end products of reaction pathway
• Directly involved in growth, development or reproduction

Examples: alcohols, amino acids, nucleotides, organic acids, vitamins, enzymes

Question 26

What are secondary metabolites and some examples?

Answer 26

• Accumulate following active growth of an organism
• Have no direct relationship to synthesis of cell material and natural growth (growth, development or reproduction)

Examples: antibiotics, toxins