Chapter 6 Flashcards
2 roles of the pentose phosphate patways
- create NADPH+H+
2. generation of a diversity of sugars
results of glycolysis
2 ATP + 2 NADH + 2 pyruvate
results of TCA
6 CO2 +8 NADH + 2 GTP + 2 FADH
resust of oxidative phosphorylation (respiratory chain and ATPase)
10 NADH + 2FADH2 = 34 ATP
results of pentose phosphate
CO2 + 2 NADPH + Cx
why pentose phsophate pathway is always running at the same time (in parallel) of fermentation and respiration
to make sure there is always enough sugar for the anabolic pathway (in case of fermentation)
what do the anaplerotic pathway in the TCA
it feeds the citric acid cycle with intermediates (produce malate to be sure there are enough)
intermediairs of the TCA are used for what
they are used in anabolic pathway (oxaloacetate can create amino acids from the aspartate family and a-ketoglutarate from the glutamate family)
where are located the enzymes for TCA cycle, respiration, oxidative phosphorylation, glycolysis and fermentation of Eukaryotes
in the cytoplasm for glycolysis and fermentation
in the mitochondria for the others
in prokaryotes, where is the respiratory chain
in the cytoplasmic membrane
in prokaryotes, where are the enzymes for glycolysis, TCA cycle and fermentation
in the cytoplasm
for both prokaryotes and eukaryotes, where is the pentose phosphate patway
in the cytoplasm
where is the TCA cycle
in the matrix of the mitochondrion
what the mitochondrion have in their membrane
ATP/ADP translocase
cytoplasm is a solution composed of what (4)
sugars, amino acids, nucleotides, salts and many other substances
how water, O2 and CO2 diffuse in the cytoplasmic membrane
water can freely diffuse but it is help by aquaporins
O2 and CO2 (small hydrophobic molecules) freely diffuse
cytoplasmic membrane- mecanism for accumulating solutes
transmembrane (integral) transport proteins
role of the permeability barrier of cytoplasmic membrane
prevents leakage and functions as a gateway for transport of nutrients into, and wastes out of the cell
characteristics of facilitated diffusion + 2 examples
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
- channel-mediated with a channel protein
- carrier-mediated with a carrier protein
characteristics of active transport
transport solutes against the concentration (or electrochemical) gradient
3 characteristics of transport systems
- it can be saturated: the rate of uptake becomes maximal and addition of more substrates do not increase the rate (all proteins are used)
- it is specific: transport single molecules or a class of closely related molecules
- biosynthesis of the transport systems are highly regulated by the cells
how nutrients are acquire in
- multicellular organisms
- unicellular (bacteria, archaea, eukaryotes)
- by diffusion or facilitated transport (from blood/plasma) since the concentration is high in the blood
- by active transport
facilitated diffusion - 2 characteristics of channel-mediated
- specificity is relatively low
2. can be close by the cell (gated channel)
facilitated diffusion- 3 characteristics of the carrier-mediated
- the binding of the substrate on one side of the membrane induces a conformational change in the carrier
- the substrate is released on the other side
- tends to be more specific than the channel-mediated diffusion
3 types of active transport + small definition of each
- simple transport: driven by the energy in the proton motive force
- group translocation: chemical modification of the transported substances driven by phosphoenolpyruvate
- ABC transporters: periplasmicbinding proteins are involved and energy comes from ATP
what is the periplasmic
space between the inner and the outer membrane of the Gram-negative bacteria
3 types of simple transport
- uniporter (only one type of molecule in one direction)
- symporter (2 different molecules in the same direction)
- antiporter (2 different molecules in opposite direction)
one example of antiporter and one of symporter
antiporter: sodium-proton which brings H+ in the cell and Na+ out
symporter: lac permease which H+ and lactose inside the cell
what happens during group translocation
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
the best characterized group translocation system is ______ and it is used by what
phosphoenolpyruvate-dependent sugar phosphotransferase system
it is used by bacteria to transport common monosaccharides such as glucose, mannose, fructose
why the glucose use the group translocation (why it is a good solution)
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
in group translocation, what is the sequence of enzymes (in order) that pass the phosphate group of the phosphoenolpyruvate + where are these enzymes
- Enz 1 to HPr (non-specific cytoplasmic components)
- Enx 11a to Enz 11b (specific components in the cytoplasmic membrane)
- Enz 11c (in the membrane)
3 components of the ABC transporters (ATP-binding cassette)
- a substrate-specific binding protein that has a very high affinity for a specific substrate (or a class of substrates)
- a membrane-spanning protein, the active transport carrier
- an ATP-hydrolyzing protein that provides the energy for the active transport
what do the binding-protein in ABC transporters and what is the concentration that it can bind its substrate
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
where are the binding-protein in Gram positive and negative bacteria
positive: anchored in the cytoplasmic membrane
negative: free in the periplasm
what happens when the respiration is not possible for bacteria and archaea
we use ATPases to create proton motive force (since there is no electron transport chain). ATPase are reversible.
Pmf-dpendent transporters are what (which type of transporters)
antoporter and symporters that use the proton gradient
pmf has a chemical and an electrical components. what are they
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
how do we know was is the driven force of the pmf
- look at the transport mechanism (ex: peoton-anion symporter)
- 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!!
what happens for the transport in unicellular eukaryotes-pmf
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
type of ATPase in eukaryotes and prokaryotes and number of H+ pump out per ATP
eukaryote: P-type ATPase = 1H+/ATP hydrolyzed
prokaryotes/mitochondria: F-type ATPase = 3 H+/ ATP hydrolyzed
3 types of endocytosis and what is essential to make it happens
- 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
role of NADPH
used as a reducing power in most anabolic reactions
