ch.6 energy crisis solved by glycolysis

Question 1

Name the evolutionary crisis that glycolysis solved, and explain what caused that crisis.

Answer 1

Glycolysis saved the enrgy criss that was caused by the proton pump. Glycolysis allows the cell to break down glucose into 2 copies of a 3 carbon compound, and thereby converts 2 ADP molecules to ATP that will supply the proton pump

Question 2

Describe the sodium/potassium pump. What is pumped out, what is pumped in? Where does the energy come from? How can this pump help solve the osmosis problem if it is pumping solute both out and in?

Answer 2

Sodium/potassium pump pumps in potassium ions, while it pumps out soudium ions. 3 sodium ions enter the pump and ATP is used to push them out of the cell since it’s a form of active transport(going against the concentration gradient). This causes ATP to become ADP+Pi. After the sodium ions exit the pump, 2 potassium ions inter the pump and the Pi breaks off to push the potassium ions into the cell, which is a form of active transport. This pump can help solve osmosis crisis if it’s pumping solute both in and out of the cell because it’s pumping out 3 sodium ions for every 2 potassium ions, which lowers the concentration of protons in the cell.

Question 3

Explain how the sodium gradient achieved by the pump facilitates food acquisition?

Answer 3

sodium gradient that is achieved by the pump facilitates food acquisition because it pumps out more that what is entering the cell (3 sodium ion: 2 potassium ions). This creates a concentration gradient, where ions are pumped back into the cell through diffusion and protein channels. However, along with ions, sugars from food are also diffused into the cell, which supplies food to the cell.

Question 4

Describe the calcium pump. Which way does calcium go? What energy required?

Answer 4

The calcium pump’s concentration gradient goes from low to high. It has a higher concentration outside than it does inside of the cell, so due to osmosis, it is leaving the cell (hyperosmotic). The energy needed is the hydrolysis of ATP, in which ATP becomes ADP+Pi.

Question 5

Know which side (in or out) of every living prokaryotic cell has more hydrogen, sodium, potassium, and calcium

Answer 5

ion: outside, inside
H+: high, low
Ca2+: high, low
K+: low, high
Na+: high, low

Question 6

Evolution of proton pump.
a. Remind yourself how the proton pump solved the osmosis crisis.

Answer 6

proton pump solved osmosis criss because it pumped protons (H+) out of the cells, which equalized solute inside the cell and lowered the concentration of protons inside of the cell

Question 7

Evolution of proton pump.
b. What crisis does the proton pump cause?

Answer 7

energy crisis

Question 8

Evolution of proton pump.
c. What solves the crisis caused by the proton pump?

Answer 8

glycolysis

Question 9

An atom or molecule with reducing power tends to (choose one) gain / donate electrons?

Answer 9

gain

Question 10

An atom or molecule that gains an electron is oxidized / reduced?

Answer 10

reduced

Question 11

An atom or molecule that loses an electron is oxidized / reduced?

Answer 11

oxidized

Question 12

Know how to assign oxidation numbers to C, H and O within a molecule.

Answer 12

All C+H+O=0
H= +1
O= -2
solve for C

Question 13

Use oxidation numbers to recognize which molecules (for example out of a set of single carbon molecules) are most reduced

Answer 13

the more negative the number, the higher the reducing power

Question 14

Know the four ways we learned in lecture to identify which player in a redox reaction is being reduced, and which is being oxidized

Answer 14

X is reduced if:
gains e-
gains H
loses O
charges become more negative

X is oxidized if:
loses e-
loses H
gains O
charges become more positive

Question 15

Explain the mechanism by which a cell establishes ionic gradients across its membrane and describe 3 ways a cell can use ionic gradients.

Answer 15

mechanism used was a pump
used for:
*pushing H+ ions out of the cell to create osmotic balance (H+ pump)
*moving flagella tail thats made of proteins, in which flow of H+ ions whips it around due repulsion of e-
*Na+/K+ pump creats high concentration of Na+ outside of the cell allows glucose transport to move glucose inside the cell due to a Na+ ion being released

Question 16

Use sketches to help you describe the first phase of glycolysis. Start with glucose (not the detailed structure, just depict glucose as a circle as we did in lecture). What happens to the glucose molecule? Use the words, glucose, investment (what is invested?), phosphorylation, ATP, ADP, splitting, glyceraldehyde-3-phosphate.

Answer 16

First, you start off with glucose. One ATP is used to phosphoralyze glucose. Then, the ohter ATP is invested to break apart glucose (6 C molecule) into 2 3C molecules (one being G3P, other just being 3C molecule). After, isomerase (enzyme) comes into play to change the 3C molecule that’s not G3P into G3P, so we have 2 G3P’s.

Question 17

Name the most important output of the investment phase. This is the input to the payoff phase. What characteristic of this molecule gives the payoff phase the capacity to create ATP’s?

Answer 17

The most important output of the investment phase is 2 molecules of G3P. The characteristic of this molecule that gives the payoff phase the ability to create ATP’s is that G3P’s have LOTS of reducing power, meaning that it really wants ot give away e-‘s. This allows a free Pi from the environment to bind, which creates 2 ATP’s when both Pi’s are broken off.

Question 18

Use sketches to describe the second phase of glycolysis. How does glyceraldehyde-3-phosphate get phosphorylated without ATP? Where exactly does the phosphate come from? Use the words, glyceraldehyde-3-phosphate, NAD+, NADH, reduction, oxidation, ATP, ADP, harvesting, pyruvate.

Answer 18

2 G3P molecules made from the investment phase get 2 phosphates from the environment for free, which gives it enough energy fro reduction of NAD+ to NADH. Crux reaction then occurs and G3P molecules adds the phosphates they got for free to itslef using the reducing powers of NADH. Then, each phosphate is broken off one by one creating an ATP for each phosphate broken off. After, you have two pyruvates made an an output of 2ATP’s.

Question 19

Summarize glycolysis as a whole:
a. How many ATP’s are made total?
b. How many ATP’s are invested (ATP—ADP + Pi)?

Answer 19

a. 4ATP’s
b. 2 ATP’s

Question 20

Summarize glycolysis as a whole:
c. Describe the reaction that replenishes NAD+. Name the reactants that get reduced and oxidized. What are the products and where do they go next?
d. How many ATP’s does glycolysis of one glucose molecule net for the cell?

Answer 20

c. Fermentation replenishes NAD+ because it takes the NADH made from glycolysis and oxidizes it to become NAD+. Then, the NAD+ made from fermentation goes back into glycolysis (becomes a cycle).
input: NADH (from glycolysis to fermentation)
output: NAD+ (from fermentation to glycolysis)
d. 2 ATP’s

Question 21

Draw an overall (net only) input output diagram of glycolysis. This is the diagram you will use later. Include in your diagram pyruvate, NADH, NAD+, ADP, Pi, ATP, Glucose. Also include in your diagram where all the inputs come from and where all the outputs go.

Answer 21

input: 2 ADP+2Pi (from proton pump), glucose (from primordial soup), NAD+ (from fermentation)
output: 2 pyruvate (to fermentation), 2 ATP (to proton pump), NADH (to fermentation)

Question 22

Name the new evolutionary crisis that glycolysis created.

Answer 22

food crisis, nothing is making glucose