Microbial Metabolism

Question 1

enzyme

Answer 1

an organic catalyst

Question 2

function of a catalyst

Answer 2

increases the rate of reaction by lowering the activation energy

Question 3

catabolism

Answer 3

the breakdown of larger molecules into smaller products, releasing energy that is generally used to synthesise ATP

Question 4

metabolic pathway

Answer 4

series of chemical reactions, typically catalysed by an enzyme, that convert an initial molecule into an end product

Question 5

activation energy

Answer 5

the energy required to weaken and break existing bonds

Question 6

endergonic

Answer 6

energy released forming new bonds is less than that required to break them

Question 7

exergonic

Answer 7

energy released forming new bonds is greater than that required to break them

Question 8

active site

Answer 8

functional site of an enzyme, its shape is complimentary to its substrate

Question 9

metabolism

Answer 9

sum total of all chemical reactions occurring within an organism

Question 10

what is the ultimate function of metabolism?

Answer 10

to gather energy and reproduce the organism

Question 11

What are the two general processes metabolism encompasses?

Answer 11

catabolism and anabolism

Question 12

anabolism

Answer 12

otherwise known as biosynthesis, stored energy (generally in the form of ATP) is used to synthesise or assemble complex molecules

Question 13

what happens to energy released from catabolic processes?

Answer 13

it is used to drive anabolic processes

Question 14

where does the energy go in an endergonic reaction?

Answer 14

it is stored in the bonds of the products of the reaction

Question 15

what are the three parts of adenosine triphosphate?

Answer 15

ribose (sugar), adenine (nitrogenous base), three phosphate groups (PO43-)

Question 16

what does ATP do for a cell?

Answer 16

stores energy to be released in exergonic reactions and supplies energy required by endergonic reactions

Question 17

ATP -> ADP exergonic or endergonic?

Answer 17

exergonic

Question 18

ADP -> ATP exergonic or endergonic?

Answer 18

endergonic

Question 19

converting ADP to ATP requires what?

Answer 19

ADP, inorganic phosphate (Pi), energy

Question 20

what kind of chemical reaction breaks ATP’s phosphate bonds? Is this exergonic or endergonic?

Answer 20

hydrolysis, exergonic

Question 21

how is the energy released from ATP hydrolysis used?

Answer 21

generally coupled to endergonic reactions by transferring the removed phosphate to another molecule (phosphorylation)

Question 22

phosphorylation

Answer 22

Phosphorylation is the addition of a phosphate (PO43−) group to a protein or other organic molecule (see also: organophosphate). Phosphorylation turns many protein enzymes on and off, thereby altering their function and activity. Protein phosphorylation is one type of post-translational modification.

Question 23

obligate aerobe

Answer 23

An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy. In this type of respiration, oxygen serves as the terminal electron acceptor for the electron transport chain. Aerobic respiration has the advantage of yielding more energy (adenosine triphosphate or ATP) than fermentation or anaerobic respiration, but obligate aerobes are subject to high levels of oxidative stress.

Question 24

an organism that requires oxygen to grow.

Answer 24

obligate aerobe

Question 25

obligate anaerobes

Answer 25

Obligate anaerobes are microorganisms that are killed by normal atmospheric concentrations of oxygen (21% O2). Oxygen tolerance varies between species, some capable of surviving in up to 8% oxygen, others losing viability unless the oxygen concentration is less than 0.5%. An important distinction needs to be made here between the obligate anaerobes and the microaerophiles. Microaerophiles, like the obligate anaerobes, are damaged by normal atmospheric concentrations of oxygen. However, microaerophiles metabolise energy aerobically, and obligate anaerobes metabolise energy anaerobically. Microaerophiles therefore require oxygen (typically 2-10% O2) for growth. Obligate anaerobes do not.

Question 26

microorganisms that are killed by normal atmospheric concentrations of oxygen but do not require it to function

Answer 26

obligate anaerobes

Question 27

microaerophile

Answer 27

microaerophiles are microorganisms that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere (i.e. <21% O2; typically 2-10% O2). many microaerophiles are also capnophiles, requiring an elevated concentration of carbon dioxide (e.g. 10% CO2 in the case of genus Campylobacter).

Question 28

microorganisms that are killed by normal atmospheric concentrations of oxygen, but require small amounts to survive

Answer 28

microaerophiles
(typically 2-10% O2). many microaerophiles are also capnophiles, requiring an elevated concentration of carbon dioxide (e.g. 10% CO2 in the case of genus Campylobacter).

Question 29

microorganism that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere

Answer 29

microaerophile
(typically 2-10% O2). many microaerophiles are also capnophiles, requiring an elevated concentration of carbon dioxide (e.g. 10% CO2 in the case of genus Campylobacter).

Question 30

capnophiles

Answer 30

capnophiles are microorganisms which thrive in the presence of high concentrations of carbon dioxide. some capnophiles may have a metabolic requirement for carbon dioxide, while others merely compete more successfully for resources under these conditions. the term is a generally a descriptive one and has less relevance as a means of establishing a taxonomic or evolutionary relationship among organisms with this characteristic.

Question 31

aerotolerant organisms

Answer 31

aerotolerant organisms do not require oxygen as they metabolise energy anaerobically. unlike obligate anaerobes however, they are not poisoned by oxygen.

Question 32

organisms that do not require oxygen but are not poisoned by its presence

Answer 32

aerotolerant organisms

Question 33

facultative anaerobe

Answer 33

a facultative anaerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent. an obligate aerobe, by contrast, cannot make ATP in the absence of oxygen, and obligate anaerobes die in the presence of oxygen.

Question 34

an organism that can function both with and without oxygen

Answer 34

facultative anaerobe

Question 35

what is the most reduced form of carbon (single atom)?

Answer 35

methane, CH4
the oxidation state of a one-carbon fragment is unambiguous and defined by the number of C-H bonds that have been replaced by C-X bonds, where X = any electronegative element. Replacing C-H bonds by C-Metal bonds is not a redox process. A C=O double bond is equivalent to two C-O single bonds (C(OH)2).

Question 36

what is the most oxidised form of carbon (single atom)?

Answer 36

CO2, carbon dioxide
the oxidation state of a one-carbon fragment is unambiguous and defined by the number of C-H bonds that have been replaced by C-X bonds, where X = any electronegative element (see periodic table on previous page). Replacing C-H bonds by C-Metal bonds is not a redox process. A C=O double bond is equivalent to two C-O single bonds (C(OH)2).

Question 37

is the burning of methane exothermic or endothermic?

Answer 37

exothermic, electrons are removed from methane (CH4)

and added to oxygen gas to form water, moving them to a lower energy level

Question 38

are organic substances naturally oxidised or reduced in their ground states?

Answer 38

organic molecules are reduced molecules (sugars, lipids, proteins, gasoline, methane, etc.)
energy is released when they are oxidised and converted from a more reduced form to an oxidized form

Question 39

where does the energy from the oxidation of reduced organic molecules in cells go?

Answer 39

most travels the electrons, some may be temporarily captured by a coenzyme such as NAD+/NADH

Question 40

NAD+/NADH which is oxidised form? which is reduced form? which is lower in energy?

Answer 40

NAD+ oxidised, NADH reduced. the oxidised form is lower in energy.

Question 41

list three of the important electron carrier molecules of cells in their oxidised and reduced forms

Answer 41

oxidised / reduced
NAD+/NADH
NADP+/NADPH
FAD/FADH2

Question 42

what are cellular electron carrier molecules derived from?

Answer 42

vitamins (ex. NAD+ and NADP+ are derived from vitamin B3)

Question 43

dehydrogenase

Answer 43

a dehydrogenase is an enzyme belonging to the group of Oxidoreductases that oxidizes a substrate by a reduction reaction that transfers one or more hydrides (H−) to an electron acceptor, usually NAD+/NADP+ or a flavin coenzyme such as FAD or FMN.