Metabolism and energetics part 2

Question 1

in the pentose phosphate pathway, what is the source of reducing power?

Answer 1

NADH + H+

Question 2

Witch pathway produces most of the NADH + H+?

Answer 2

pentose phosphate pathway

Question 3

which pentose is used to produce ribose and deoxyribose?

Answer 3

Ribose 5‐phosphate

Question 4

The pentose phosphate pathway leads to what?

Answer 4

the generation of a diversity of sugars. (gluconeogenesis)

Question 5

where does pentose phosphate pathway take place (Prokaryotes and Eukaryotes) ?

Answer 5

In the cytoplasm

Question 6

EUKARYOTES: where are the enzymes of the TCA cycle for respiration and oxidative phosphorylation located?

Answer 6

in the mitochondria

Question 7

EUKARYOTES: where are the enzymes of glycolysis and fermentation located?

Answer 7

in the cytoplasm.

Question 8

PROCARYOTES: where is the respiratory chain located?

Answer 8

cytoplasmic membrane

Question 9

PROCARYOTES: where are the enzymes of glycolysis, TCA cycle and fermentation located?

Answer 9

cytoplasm

Question 10

EUKARYOTES: where does the pentose phosphate pathway occur?

Answer 10

cytoplasm

Question 11

PROCARYOTES: where does the pentose phosphate pathway occur?

Answer 11

cytoplasm

Question 12

what is the cytoplasm made of?

Answer 12

Cytoplasm is a solution of salts, sugars, amino acids, nucleotides, and many other substances.

Question 13

why is it important for the cytoplasmic membrane to be hydrophobic?

Answer 13

The hydrophobic portion of the cytoplasmic membrane prevents the diffusion of those substances. Those referring to what the cytoplasm is made of.

in other words, it acts like a permeability barrier: prevents leakage and functions as a gateway for transport of nutrients into, and waste out, of the cell.

Question 14

What can/cannot diffuse through the cytoplasmic membrane?

Answer 14

• Some small hydrophobic molecules can diffuse through the membrane (O2, CO2)
• Water can freely diffuse, and is helped along by aquaporins
• Polar and charged molecules cannot diffuse, must be transported
another way

Question 15

Name the different types of transport events and explain the difference:

Answer 15

• Facilitated diffusion can only transport solutes down a gradient. For uncharged substrates, the concentration gradient alone will determine the direction of the flow. For charged substrates, the concentration gradient and the charge will determine the direction of the flow. (channel mediated and carrier mediated)
• Active transport can transport solutes against the concentration (or electrochemical) gradient. But requires energy. (simple transport, group translocation, ABC transporter)

Question 16

explain these concepts concerning the transport system:

• saturation
• specificity

Answer 16

• Transport systems can be saturated; the rate of uptake becomes maximal and addition of more substrate does not increase the rate.
• Transport systems are specific; transport single molecule or a class of closely related molecules.

Question 17

which transport system do multicellular organism use to acquire nutrients? unicellular?

Answer 17

• In multicellular organisms, cells usually acquire nutrients by means of diffusion or facilitated diffusion (from blood / plasma).
• In unicellular organisms, including bacteria, archaea and eukaryotes, nutrients are usually acquired by active transport.

Question 18

explain the difference between channel mediated and carrier mediated facilitated diffusion:

Answer 18

• 1) Channel‐mediated:
– Specificity is relatively low
– Can be closed by the cell (gated channel)
• 2) 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 channel‐mediated diffusion.

Question 19

what does ‘going against the gradient’ imply for substrates?

Answer 19

the cells need to concentrate building blocks and energy‐ rich molecules.

Question 20

explain simple trasnport

Answer 20

• driven by the energy in the proton motive force
• requires energy because against the concentration gradient
• you have uniporter, symporter, antiporter
• Sodium-Proton Antiporter: H+ goes in and Na+ goes out
• Lac permease H+ goes in with lactose