Exam 2: Ch 7: Microbial Metabolism

Question 1

Metabolism

Answer 1

pertains to all chemical reactions and physical workings of the cell

Question 2

Anabolism

Answer 2

synthesis of molecules - building stuff up
requires input of energy
need to take smaller molecules & ATP to make larger molecules

Question 3

Catabolism

Answer 3

breaks the bonds of larger molecules - breaking stuff down
releases energy
take larger molecules & get smaller molecules and energy

Question 4

Electron transfer

Answer 4

allows energy to be captured in high-energy bonds in ATP and similar molecules
All catabolic reactions involve it & Cellular respiration is built on it
Directly related to oxidation & reduction electron being passed from one protein to another
By transferring the e-, energy is transferred from A → B

Question 5

Oxidation

Answer 5

loss of electrons

Question 6

Reduction

Answer 6

gaining of electron

the charge is reduced but it now has more energy than it did before

Question 7

Oxidoreductase

Answer 7

enzymes that remove electrons from one substrate and add them to another
their coenzyme carriers are NAD+ and FAD
H+ is often going along in this process

Question 8

Activation energy

Answer 8

the minimal amt of energy required to be available for bonds to be formed or broken
can be in the form of temp, pressure, etc to increase the number of particle collisions (we don’t have time to wait, so we speed up the reaction with heat/pressure/etc)

Question 9

Why do humans need enzymes?

Answer 9

The temp and pressure that humans and bacteria would require for their chemical reactions would kill them – so we need ENZYMES
Enzymes reduce the amt of activation energy needed for chemical reactions and speed them up so that life can continue

Question 10

Enzymes

Answer 10

reduce the amt of activation energy needed for chemical reactions
have specific active sites that bind to specific substrates
Bonds formed btwn the substrate and enzyme are weak and easily reversible
Enzymes are fast!
The # of substrate molecules converted per enzyme per second
Catalase – reacts several million times/sec
Lactase dehydrogenase – reacts a thousand times/sec

Question 11

Specific active sites

Answer 11

arise due to the folding of a protein (folding is what allows for active sites and the activity of enzymes)
One little change could change the enzyme and make it useless

Question 12

Substrates

Answer 12

specifically bind to active sites on the enzyme

lock & key

Question 13

What happens at the end of enzyme-substrate reactions?

Answer 13

once the reaction is complete, the product is released and the enzyme reused

Question 14

Cofactors

Answer 14

participate in precise functions btwn the enzyme and substrate
help bring the active site and substrate close together
participate directly in chemical reactions with the enzyme substrate complex
The need for trace elements for microorganisms arises from their roles as cofactors for enzymes

Question 15

Coenzymes (vitamins)

Answer 15

organic compounds that work in conjunction with an enzyme
remove a chemical group from one substrate molecule and add it to another substrate molecule
Carry and transfer hydrogen atoms, electrons, carbon dioxide, and amino groups

Question 16

Apoenzyme

Answer 16

globular protein that is the main enzyme portion

“the protein part”

Question 17

How do we regulate enzymes?

Answer 17

Adjust for the level you need at that particular time and in that particular situation
use constitutive & regulated enzymes
negative feedback loop
helps reduce waste from making enzymes that arent needed

Question 18

Constitutive enzymes

Answer 18

always present in relatively constant amounts regardless of the amount of substrate
keep substrate up → turn the enzyme down
ex. catalase

Question 19

Regulated enzymes

Answer 19

production is turned on (induced) or turned off (repressed) in responses to changes in concentration of the substrate
regulated thru gene expression

Question 20

How is enzyme function regulated?

Answer 20

Activity of enzymes influenced by the cell’s environment (natural temp, pH, osmotic pressure)

Denaturation - the weak bonds that maintain native shape of enzyme are broken

Question 21

Competitive inhibition

Answer 21

inhibits enzyme activity by supplying a molecule that resembles the enzymes normal substrate
“mimic” occupies the active site, preventing the actual substrate from binding
Actually binds to active site

Question 22

Noncompetitive inhibition

Answer 22

bind to an “allosteric” or “other” site on the enzyme, not the active site
Changes the configuration of the active site so the normal substrate cant bind

Question 23

Metabolic pathways

Answer 23

Often occur in a multistep series/ pathway
each step catalyzed by an enzyme

Metabolic pathways do not stand alone - they are interconnected and merge at many sites

Question 24

Linear pathway

Answer 24

production of one reaction is the reactant (substrate) for the next
linear chain reaction
if an enzyme gets cut out, you dont get the next step

Question 25

Branched pathway

Answer 25

Many pathways have branches that provide alternate methods for nutrient processing
fixes the problem in linear where a cut enzyme inhibits the rest

Question 26

Divergent branched pathway

Answer 26

taking 1 thing and making multiple things from it

1 input and 2 different outputs/directions

Question 27

Convergent branched pathway

Answer 27

multiple things can make 1 thing

Question 28

Cyclic pathway

Answer 28

starting molecule is regenerated to initiate another turn of the cycle
start w/a molecule and get back to that molecule

Question 29

Electron carriers

Answer 29

Cell’s reducing power
NAD+ and FAD
Carriers resemble shuttles that load and unload electrons and hydrogens to facilitate transfer of redox energy

Electrons available in NADH and FADH2

Electrons are transferred in many cases along w/protons as hydrogen atoms since one hydrogen atom (H) = 1 proton (H+) plus 1 electron (e-)

Question 30

Adenosine Triphosphate (ATP)

Answer 30

Three part molecule:
-Nitrogen base (adenine)
-5-carbon sugar (ribose)
-chain of 3 phosphate groups bonded to ribose
Can be used to phosphorylate an organic molecule (ex. phosphorylation of glucose activates its catabolism)
Phosphate groups: bulky and carry negative charges –> cause a strain btwn the last 2 phosphates making it very volatile
No storage aspects of ATP because its so unstable – its your “right now” energy

Question 31

Aerobic respiration

Answer 31

series of reactions that converts glucose to CO2 and allows the cell to recover significant amounts of energy
Complete breakdown of pyruvic acid into inorganic molecules
FEA - O2 (free O2)

Characteristic of many fungi, bacteria, protozoa, and animals

Question 32

Anaerobic respiration

Answer 32

FEA: NO3-, SO42-, CO33- and other oxidized compounds

Like aerobic respiration – there is a complete breakdown of pyruvic acid into inorganic molecules
Unlike aerobic respiration – does not use all of the steps in the Kreb’s cycle

Question 33

Fermentation

Answer 33

lots of sugar and no oxygen
Unlike aerobic and anaerobic respiration, pyruvic acid is not completely broken down into inorganic molecules
Pyruvic acid is partially broken down into organic compounds that are the final electron acceptors