Microbiology Exam 3

Catabolism is ________ whereas anabolism is _________

break down; synthesis

How many parts of the nitrogen cycle are done solely by microbes?

4

How many parts of the nitrogen cycle are microbes a part of?

8

1 cal = _____ J

4.184

What type of reaction is this?

exergonic

What type of reaction is this?

endergonic

ΔG for an exergonic reaction is positive. True or False

false it is negative

Are endergonic reactions spontaneous or nonspontaneous?

nonspontaneous

Where is the energy stored in an endergonic reaction?

in the bonds

Exergonic reactions

• -ΔG

• spontaneous

• energy released

Endergonic reactions

• +ΔG

• nonspotaneous

• energy entering

GTP is involved in ______ synthesis

protein

Lipid synthesis uses ____

CTP

UTP is involved in what synthesis?

peptidoglycan

What is -ΔG for ATP hydrolysis?

-7.3 kcal/mol

ATP has the highest phosphate transfer potential. True or False

false it is not the highest but it is still high

You have two redox potentials -0.68 and 0.84 which one is the electron donor and electron acceptor?

-0.68 = electron donor (oxidation)

0.84 = electron acceptor (reduction)

What are all the names of oxidation?

electron donor, reductant, reducing agent

What are all the names of reduction?

electron acceptor, oxidant, oxidizing agent

What are the 2 rules of redox pairs?

1. reduced member that is more negative donates electrons to the oxidized member that is more positive

2. greater the difference in redox potential the greater amount of energy available

When ΔG is less than 0 what is the redox potential and direction of reaction?

redox potential is greater than 0

reaction is spontaneous is forward direction

When ΔG is greater than 0 what is the redox potential and direction of reaction?

redox potential is less than 0

reaction is spontaneous is reverse direction

What is Faraday’s constant?

23 kcal/volt

96.5 kJ/volt

What is the Nernst equation?

ΔG⁰' = -nFE^{o ‘}

Where is the ETC in prokaryotes versus eukaryotes?

eukaryotes = mitochondria

prokaryotes = cell membrane

What electron carrier in the ETC is the most negative redox potential?

the first electron carrier, NADH

Which of the electron carriers accepts two electrons and one proton?

NADH and NADPH

What are the flavoproteins and how many electrons and protons do they accept?

FAD and FMN

carry 2 electrons and 2 protons

What is a lipid that transports two electrons and two protons?

CoQ/ubiquinone

Which electron transport carrier uses iron and is part of a heme group that carries 1 electron?

cytochromes

Ferredoxin is an example of _________

nonheme iron-sulfur protein

Nonheme iron-sulfur protein carry _____ electron

1

What is the difference in binding for prosthetic groups and coenzymes?

prosthetic group = covalently bound to enzyme

coenzyme = loosely bound to enzyme

What is a holoenzyme composed of?

apoenzyme + cofactor

What is the transition state complex?

when the reactants come together; at the top of the graph

How do enzymes lower activation energy?

• increasing substrate concentration at active site

• orienting substrates properly

Reaction rate _______ as [substrate] increases

increases

A higher Km means what?

higher [substrate]

Would amylase work in the stomach?

no because pH is specific to each enzyme and have their own optimum pH

Sulfa drugs are an example of a ________ inhibitor. Why?

competitive; they resemble PABA

What is an example of a noncompetitive inhibtor?

poisons like cyanide

What are ribozymes made up of?

RNA

What are functions of ribozymes?

1. catalyze peptide bond formation

2. self splicing

3. involved in self replication

How do cells regulate metabolism?

1. compartmentation

2. transcriptional & translational

3. post-translational

Prokaryotes don’t have compartmentation. True or False

false they do

What are examples of reversible post-translational mechanisms?

• allosteric regulation

• covalent modification

What are isoenzymes?

different forms of enzymes that bind to same substrate

Pacemaker enzymes are the first enzyme of the pathway. True or False

false they usually are but not always

What are the carbon, electron, and energy source for a photolithoautotroph?

carbon = CO2

energy = light

electron = inorganic electron donor

Plants are an example of what type of nutritional organism?

photolithoautotrophs

What type of organism uses organic carbon, light, and organic electron donor?

photoorganoheterotroph

CO2, inorganic materials, and inorganic electron donor are for what organism?

chemolithoautotroph

What does a chemolithoheterotroph use?

organic carbon, inorganic chemicals, inorganic electron donor

What is the difference between heterotrophs and autotrophs?

heterotroph = use organic molecules

autotroph = use single carbon molecule, CO2

Which of the microorganisms are primary producers?

photolithoautotrophs/photoautotrophs & chemolithoautotrophs

The majority of pathogens are ________

chemoorganoheterotrophs '

What are the basic needs of all living organisms?

• ATP as an energy currency

• reducing power to supply electrons for chemical reactions

• precursor metabolites for biosynthesis

Oxygen is the difference between fermentation and respiration. True or False

false

What can chemoorganotrophs do that chemolithotophs can’t?

fermentation

What is the difference between fermentation and respiration?

ETC = respiration

no ETC = fermentation

What are the 6 requirements for all life?

CHONPS

Where are electrons donated in fermentation?

to an endogenous acceptor

What is the difference between aerobic and anaerobic respiration?

the final electron acceptor differs

aerobic = oxygen

anaerobic = not oxygen, an exogenous acceptors

Where is the ATP made through respiration?

SLP and oxidative phosphorylation

What is an example of an endogenous electron acceptor?

pyruvate

What is the pacemaker enzyme in glycolysis?

phosphofructokinase

What are the routes of glycolysis?

1. EMP (most common)

2. ED

3. PPP

Are archaea able to go through beta-oxidation? Why?

no because beta oxidation uses fatty acids which archaea do not have, they have isoprene units

What is an commonality between all 3 glycolysis routes?

all convert glucose to G3P

What is the net gain of ATP from the EMP pathway?

2 ATP

How many NADHs are made from glycolysis?

2 NADH

The EMP pathway functions only in the presence of oxygen. True or False

false it works with or without O2

What is the order of glycolysis?

glucose, G6P, F6P, F1,6-BP, G3P, 3-phosphoglycerate, PEP, pryuvate

What type of bacteria use the ED pathway? Give an example.

soil bacteria and a few gram (-) bacteria; ex = Bacillus

Would yeast use the ED pathway? Why or why not?

no because yeast is a type of fungi which is eukaryotic and eukaryotes don’t use ED pathway

What is major difference between the EMP and ED pathway in terms of the pathway intermediates?

the ED pathway produces 2-keto-3-deoxy-6-phosphogluconate (KDPG)

Why does the ED pathway produce 1 ATP while EMP produces 2?

because only 1 G3P is made; KDPG becomes pyruvate and G3P

PPP is a major source of what electron carrier?

NADPH

What is important about E4P and ribose-5-phosphate?

make RNA nucleotides

PPP works at the same time as EMP. True or False

true

Does the Kreb’s cycle work in anaerobic bacteria?

no

What is yield of TCA?

• 6 NADH

• 2 FADH2

• 2 ATP

What is the role of pyruvate dehydrogenase?

oxidizes and cleaves pyruvate into acetyl-CoA and CO2

What type of bond is present in acetyl-CoA?

thioester bond, which yields a lot of energy

The ATP produced after succinyl-CoA is due to what?

SLP

Why is alpha-ketoglutarate important in TCA?

important in the making of amino acids

What is overall occurring in TCA?

the carbons from glucose are getting oxidized while NADH is getting reduced through gaining those electrons

What 2 places in the Kreb’s cycle are the thioester bond found?

succinyl-CoA and acetyl-CoA

Where is the ETC located in bacteria vs eukaryotes?

bacteria = cell membrane

eukaryotes = inner mitochondrial membrane

Where does the NADH come from in the ETC?

from TCA and glycolysis

Complex I in the has a negative or positive reduction potential? Why?

negative because the higher the reduction potential is the more likely it is to be reduced so the first complex has to be the lowest so the other ones can accept the electrons

If there is a high concentration of cytochrome c outside the mitochondria what does that mean about the cell?

the cell is not healthy

Glucose is a better _____ and ½ O2 is a better ______

glucose = electron donor (oxidized)

½ O2 = electron acceptor (reduced)

What is a coupling site and which of the complexes does not do this?

coupling site = where protons are being pumped

complex II is NOT a coupling site

What does CoQ connect?

connects complex I to III and complex II to III

What does cytochrome c connect?

complex III to IV

Complex II participates in pmf. True or False

false since it does not pump H+

If rotenone and malonate were given how many ATP would be created?

4 ATP (2 from glycolysis +2 from TCA)

What happens when rotenone is given?

it inhibits complex I so NADH accumulates and there is no NAD+ so glycolysis can’t move forward and the cell dies

Where are protons present in gram (-) bacteria?

periplasmic space