Chapter 6

Question 1

2 roles of the pentose phosphate patways

Answer 1

1. create NADPH+H+

2. generation of a diversity of sugars

Question 2

results of glycolysis

Answer 2

2 ATP + 2 NADH + 2 pyruvate

Question 3

results of TCA

Answer 3

6 CO2 +8 NADH + 2 GTP + 2 FADH

Question 4

resust of oxidative phosphorylation (respiratory chain and ATPase)

Answer 4

10 NADH + 2FADH2 = 34 ATP

Question 5

results of pentose phosphate

Answer 5

CO2 + 2 NADPH + Cx

Question 6

why pentose phsophate pathway is always running at the same time (in parallel) of fermentation and respiration

Answer 6

to make sure there is always enough sugar for the anabolic pathway (in case of fermentation)

Question 7

what do the anaplerotic pathway in the TCA

Answer 7

it feeds the citric acid cycle with intermediates (produce malate to be sure there are enough)

Question 8

intermediairs of the TCA are used for what

Answer 8

they are used in anabolic pathway (oxaloacetate can create amino acids from the aspartate family and a-ketoglutarate from the glutamate family)

Question 9

where are located the enzymes for TCA cycle, respiration, oxidative phosphorylation, glycolysis and fermentation of Eukaryotes

Answer 9

in the cytoplasm for glycolysis and fermentation

in the mitochondria for the others

Question 10

in prokaryotes, where is the respiratory chain

Answer 10

in the cytoplasmic membrane

Question 11

in prokaryotes, where are the enzymes for glycolysis, TCA cycle and fermentation

Answer 11

in the cytoplasm

Question 12

for both prokaryotes and eukaryotes, where is the pentose phosphate patway

Answer 12

in the cytoplasm

Question 13

where is the TCA cycle

Answer 13

in the matrix of the mitochondrion

Question 14

what the mitochondrion have in their membrane

Answer 14

ATP/ADP translocase

Question 15

cytoplasm is a solution composed of what (4)

Answer 15

sugars, amino acids, nucleotides, salts and many other substances

Question 16

how water, O2 and CO2 diffuse in the cytoplasmic membrane

Answer 16

water can freely diffuse but it is help by aquaporins

O2 and CO2 (small hydrophobic molecules) freely diffuse

Question 17

cytoplasmic membrane- mecanism for accumulating solutes

Answer 17

transmembrane (integral) transport proteins

Question 18

role of the permeability barrier of cytoplasmic membrane

Answer 18

prevents leakage and functions as a gateway for transport of nutrients into, and wastes out of the cell

Question 19

characteristics of facilitated diffusion + 2 examples

Answer 19

can only transport solutes down the gradient. For uncharged substrates, the concentration gradient alone will determine the direction of the flow. For charged substrates, the concentration and the charge will determine the direction of the flow

1. channel-mediated with a channel protein
2. carrier-mediated with a carrier protein

Question 20

characteristics of active transport

Answer 20

transport solutes against the concentration (or electrochemical) gradient

Question 21

3 characteristics of transport systems

Answer 21

1. it can be saturated: the rate of uptake becomes maximal and addition of more substrates do not increase the rate (all proteins are used)
2. it is specific: transport single molecules or a class of closely related molecules
3. biosynthesis of the transport systems are highly regulated by the cells

Question 22

how nutrients are acquire in

1. multicellular organisms
2. unicellular (bacteria, archaea, eukaryotes)

Answer 22

1. by diffusion or facilitated transport (from blood/plasma) since the concentration is high in the blood
2. by active transport

Question 23

facilitated diffusion - 2 characteristics of channel-mediated

Answer 23

1. specificity is relatively low

2. can be close by the cell (gated channel)

Question 24

facilitated diffusion- 3 characteristics of the carrier-mediated

Answer 24

1. the binding of the substrate on one side of the membrane induces a conformational change in the carrier
2. the substrate is released on the other side
3. tends to be more specific than the channel-mediated diffusion

Question 25

3 types of active transport + small definition of each

Answer 25

1. simple transport: driven by the energy in the proton motive force
2. group translocation: chemical modification of the transported substances driven by phosphoenolpyruvate
3. ABC transporters: periplasmicbinding proteins are involved and energy comes from ATP

Question 26

what is the periplasmic

Answer 26

space between the inner and the outer membrane of the Gram-negative bacteria

Question 27

3 types of simple transport

Answer 27

1. uniporter (only one type of molecule in one direction)
2. symporter (2 different molecules in the same direction)
3. antiporter (2 different molecules in opposite direction)

Question 28

one example of antiporter and one of symporter

Answer 28

antiporter: sodium-proton which brings H+ in the cell and Na+ out
symporter: lac permease which H+ and lactose inside the cell

Question 29

what happens during group translocation

Answer 29

the substrate will be modified as it passes through the transporter accross the membrane.
For example, the glucose will become the glucose-6-phosphate when it comes out of the transporter, which is the first step of glycolytic pathway in prokaryotes

Question 30

the best characterized group translocation system is ______ and it is used by what

Answer 30

phosphoenolpyruvate-dependent sugar phosphotransferase system
it is used by bacteria to transport common monosaccharides such as glucose, mannose, fructose

Question 31

why the glucose use the group translocation (why it is a good solution)

Answer 31

because the glucose has a tendency to diffuse out of the cell so want way to keep it inside is to give it a charge (phosphorylates) so it will not be able to pass through the membrane anymore

Question 32

in group translocation, what is the sequence of enzymes (in order) that pass the phosphate group of the phosphoenolpyruvate + where are these enzymes

Answer 32

1. Enz 1 to HPr (non-specific cytoplasmic components)
2. Enx 11a to Enz 11b (specific components in the cytoplasmic membrane)
3. Enz 11c (in the membrane)

Question 33

3 components of the ABC transporters (ATP-binding cassette)

Answer 33

1. a substrate-specific binding protein that has a very high affinity for a specific substrate (or a class of substrates)
2. a membrane-spanning protein, the active transport carrier
3. an ATP-hydrolyzing protein that provides the energy for the active transport

Question 34

what do the binding-protein in ABC transporters and what is the concentration that it can bind its substrate

Answer 34

it binds to its substrate and transfers it to the transporter.
it can bind its substrate at very low concentration: less than 10^-6 M

Question 35

where are the binding-protein in Gram positive and negative bacteria

Answer 35

positive: anchored in the cytoplasmic membrane
negative: free in the periplasm

Question 36

what happens when the respiration is not possible for bacteria and archaea

Answer 36

we use ATPases to create proton motive force (since there is no electron transport chain). ATPase are reversible.

Question 37

Pmf-dpendent transporters are what (which type of transporters)

Answer 37

antoporter and symporters that use the proton gradient

Question 38

pmf has a chemical and an electrical components. what are they

Answer 38

electrical: due to the difference in charge
chemical: due to the difference of in concentration (of protons or sodium) so it when we have the protn gradient

Question 39

how do we know was is the driven force of the pmf

Answer 39

1. look at the transport mechanism (ex: peoton-anion symporter)
2. look at the net charge (ex:0)
   * * if the net charge is 0, the electrical components does not have a role in the driven force
   * * if there is no proton (for H+ transporter) or no Na+ (for Na+ transporter), the chemical gradient does not have a role!!

Question 40

what happens for the transport in unicellular eukaryotes-pmf

Answer 40

since the pmf is created inside the mitochondria, a pmf needs to be created at the level of the cytoplasmic membrane. For that, a P-type ATPase (a proton-translocating ATPase) uses ATP to pump out protons.
The pmf creates at the cytoplasmic membrane can now be used to power-up symporters in the cytoplasmic membrane

Question 41

type of ATPase in eukaryotes and prokaryotes and number of H+ pump out per ATP

Answer 41

eukaryote: P-type ATPase = 1H+/ATP hydrolyzed

prokaryotes/mitochondria: F-type ATPase = 3 H+/ ATP hydrolyzed

Question 42

3 types of endocytosis and what is essential to make it happens

Answer 42

• actin filaments
• phagocytosis: for large and solid molecules, called a phagosomes when there is food vacuole that is create
• pinocytosis: non-specific, take extracellular fluid with molecules inside and form vesicle
• receptor-mediated endocytosis: specific, there is coat protein, form coated vesicle

Question 43

role of NADPH

Answer 43

used as a reducing power in most anabolic reactions