L3 microbial metabolism

Question 1

What is meant by metabolism

Answer 1

Chemical reactions that occur within the cell to maintain normal functioning and growth
Mediated by enzymes and fuelled by the input of energy by nutrition

Question 2

What can microbes use as nutrition

Answer 2

Wood, humans, water, metal etc.

Question 3

What is catabolism
What is catabolism used for

Answer 3

Breakdown of molecules into simple forms
Used for energy generation and supplying building blocks for growth

Question 4

What is anabolism
Does it require energy

Answer 4

= biosynthesis = construction of complex molecules from simpler ones
Energy requiring

Question 5

Does catabolism occur quickly or slowly and why

Answer 5

Gradual breakdown, if broken down too quickly then massice release of energy occurs which can be harmful

Question 6

What are the key atomic nutrients for life

Answer 6

C, N, S, O, H, P

Question 7

What 2 things are used to describe organisms (microbes)

Answer 7

How they obtain energy and carbon

Question 8

What is a phototroph

Answer 8

A microbe that generates energy from light

Question 9

What is a chemotroph

Answer 9

A microbe generating energy from the chemical arrangement of molecules (organic or inorganic)

Question 10

What is the name for a microbe which fixes carbon dioxide as its principal carbon source

Answer 10

Autotroph

Question 11

What is the name for a microbe which uses external (organic) sources of carbon for biosnythesis

Answer 11

Heterotroph

Question 12

What is a mixotroph

Answer 12

Able to carry out both autotrophy and heterotrophy
Can fix carbon from both carbon dioxide and organic sources

Question 13

What is a photoautotroph
Give an example

Answer 13

Uses light and carbon diocide
Photosynthetic cyanobacteria

Question 14

What is a photoheterotroph
Give an example

Answer 14

Use light and organic carbon
Purple / green bacteria

Question 15

What is a chemoheterotroph
Give an example

Answer 15

Uses chemical energy and organic carbon source
Enterobacteria

Question 16

What is a chemoautotroph
Give an example

Answer 16

Use chemnical energy and carbon dioxide as carbon source
Ammonia oxidising bacteria

Question 17

What are the two additional terms used to seperate chemotrophs based on whether their carbon source is organic or inorganic

Answer 17

Organotroph = organic molecules
Lithotroph = inorganic molecules

Question 18

Give an example of an energy source a chemolithotroph might use

Answer 18

H2
Fe2+
H2S
NH4+

Question 19

What is another word for direct interaction between microbes

Answer 19

Antagonistic

Question 20

ow can microbes interact indirectly

Answer 20

One species affects the environment to exclude another species

Question 21

What is niche partitioning

Answer 21

Where microbes occupy the same space but compete for different resources

Question 22

Explain how redox reactions can occue without movement of elevtrons

Answer 22

Redox reactions refer to a change in oxidation state
Oxidation increases the oxidation state, reduction decreases it

Question 23

What does the oxidation state represent

Answer 23

The number of electrons that an atom can gain, lose or share when chemically bonding with an atom of another element

Question 24

A reduced compound becomes … during oxidation

Answer 24

Oxidised

Question 25

What is the role of oxidoreductases

Answer 25

Accept and transfer electrons in the electron transport chain

Question 26

What are the first and second laws of energy (thermodynamic laws)

Answer 26

In energy transformations, the total energy remains constant
In energy transformations, some energy created disorder (entropy) and not work (systems tend to become more disordered)

Question 27

What is enthalpy

Answer 27

The total energy of a system

Question 28

What is enthalpy measured in

Answer 28

Joules (or heat)

Question 29

What is the equation for enthalpy (H)

Answer 29

H = G + T * S
G - free energy
T - temperature
S - entropy (disorder) = unusable energy

Question 30

What is the equation for Gibbs free energy

Answer 30

∆G = ∆H - T∆S
∆H - heat energy released or absorbed (enthalpy)
∆S - measure of disorder (change in entropy)
T - temperature

Question 31

If an organism absorbs heat from its environment, is ∆H positive or negative

Answer 31

Positive

Question 32

If a reaction splits one molecule into two, does ∆S increase or decrease

Answer 32

Increases (more disorder)

Question 33

Is ∆S more lilely to be positive for catabolic or anabolic reactions

Answer 33

Catabolic

Question 34

What is Gibbs free energy used to predict

Answer 34

The direction of a chemical reaction

Question 35

If ∆G is positive, which direction is the reaction likely to go in

Answer 35

Reverse

Question 36

What are 3 other factors affecting biochemical reactions

Answer 36

Concentration of reagents
Environmental conditions
Linked reactions
Activation energy
Enzymes

Question 37

What does ∆G˚ mean in terms of the environment

Answer 37

Standard conditions of temperature, pressure and reactant concentrations

Question 38

What does ∆G˚’ mean in terms of the environment of a reaction

Answer 38

Standard conditions plus biochemically relebany conditions pH7 and water activity 1

Question 39

What happens in hydrolysis

Answer 39

Chemical bonds broken via oxidation by water

Question 40

Give an example of energy reactions being coupled with unfavourable reactions in a cell

Answer 40

Glucose phosphorylation coupled with ATP dephosphorylation

Question 41

What is activation energy

Answer 41

Energy input required for a chemical reaction to occur

Question 42

What effect to enzymes have on activation energy

Answer 42

Lower it