Microbial Nutrition

Question 0

How do viruses obtain nutrients?

Answer 0

Obtain ‘resources’

Question 1

Why do microorganisms require food?

Answer 1

For synthesis of molecular constituents of the cell and as an energy supply

Question 2

How do cynobacteria and algae obtain nutrients?

Answer 2

Photosynthesis

Question 3

How do protozoa obtain nutrients?

Answer 3

Ingest solid food particles

Question 4

How do bacteria and fungi obtain nutrients?

Answer 4

Receive nutrients in aqueous solution, digestion outside cell and secrete enzymes into the environment

Question 5

What are the basic nutrients required for microorganisms?

Answer 5

Carbon, nitrogen, inorganic ions (phosphate, sulphate) essential metabolites and water

Question 6

What are chemoheterotrophs?

Answer 6

Include bacteria, fungi, protozoa and all higher animals. They use complex organic materials for carbon and energy source

Question 7

What are chemo autotrophs?

Answer 7

Include bacteria such as thiobacillus. They use carbon dioxide for their carbon source and use inorganic materials as energy source

Question 8

What are photoheterotrophs?

Answer 8

Includes the purple non sulphur bacterium rhidospirillum and they use sunlight as energy source and complex organic materials as carbon source

Question 9

What are photo autotrophs?

Answer 9

Includes all green plants, cynobacteria, and they use sunlight as energy source and fix carbon dioxide as carbon source

Question 10

How do bacteria obtain energy from organic nutrients?

Answer 10

Respiration or fermentation

Question 11

What are the three main points for respiration in microorganisms?

Answer 11

The substrate is oxidised by oxidising agents obtained from the environment. It gives up to 38 ATP per molecule of glucose and oxygen is used as the terminal electron acceptor in aerobic respiration

Question 12

In anaerobic respiration what is the alternative terminal electron acceptor?

Answer 12

Carbon dioxide or inorganic ions such as sulphate and nitrate

Question 13

What are the three main points for fermentation in microorganisms?

Answer 13

There is no overall net oxidation. The substrate is broken down by small steps and the net yield is 2 ATP per molecule of glucose

Question 14

What are the three main steps in respiration?

Answer 14

1. Through glycolysis a NADH molecule is released and the product of glycolysis pyruvic acid is used in the kreb cycle which is catalysed by the co enzyme acetyl.
2. During the kreb cycle a carbon dioxide molecule, ATP and NADH are released.
3. The NADH molecules are used for the electron transport chain and chemiosmosis. ATP is released and oxygen is used. Water is the final product.

Question 15

Describe glycolysis and how it’s related to fermentation

Answer 15

2 NADH molecules are released and 2 ATP to make 2 pyruvic acid molecules. 2 NADH molecules are used to reduce the pyruvic acid to form fermentation end products like lactic acid

Question 16

Name four ways of identifying bacteria

Answer 16

Gram stain
Catalase test
Oxidase test
O-F test

Question 17

What are the comparisons of gram negative and gram positive cell walls?

Answer 17

Gram positive cells walls have peptidoglycan and plasma membrane. Gram negative cell walls have peptidoglycan, plasma membrane and an outer membrane

Question 18

What are the 5 main steps in the gram stain procedure?

Answer 18

Heat fixation of the slide to ensure cells aren’t washed away.
Flood with crystal violet for 15 seconds
Flood with iodine for 15 seconds
Decolorisation by alternately flooding with alcohol and waster until no more colour is washed away.
Flood with saffronin for 15 seconds

Question 19

If a bacteria is catalase positive what will be observed?

Answer 19

Bubbles of oxygen from hydrogen peroxide

Question 20

What is the oxidase test looking for and what will happen if the test is positive?

Answer 20

Presence of cytochrome c oxidase and a positive result gives a blue colour

Question 21

What does the O-F test look for and why is it useful?

Answer 21

Used to determine if gram negative bacteria metabolise carbohydrates oxidative lay or by fermentation.
It also differentiates between aerobes/ anaerobes and facultative anaerobes

Question 22

What will be observed if the test is oxidative?

Answer 22

Green colour

Question 23

What will be observed if test is fermentative?

Answer 23

Yellow colour