1.
Discuss the importance of glucose metabolism and ATP formation
Glucose is the immediate and most preferred source of energy for most of our cells
in the body. However, there are some cells which can use some other molecules
like the lipids and proteins as the energy source. But all cells essentially able to use
glucose as an energy source. Some cells use glucose as a major source of fuel, like
nerve cells, RBCs and exercising muscle cells.
In need of the energy, the cell firstly metabolize glucose, so we can say it is readily
available source of instant energy.
Furthermore, the other macromolecules like Lipids and proteins also get converted
to glucose or the metabolites of the pathway for glucose metabolism (like Acetyl
CoA, intermediates of TCA cycle). So glucose metabolism is very important for
ATP production.
2. Write two equations comparing photosynthesis to aerobic respiration. List
reactants, end-products, and energy flow for each
Reaction for cellular respiration
C6H12O6 + 6O2 --------- 6CO2 + 6H2O + ATP (energy)
Energy present in the glucose gets converted to the energy currency in form of
ATP which is usable by the cell
Reaction of Photosynthesis
6CO2 + 6H2O + solar energy → C6H12O6 (Glucose) + 6O2.
During the reaction the solar energy get trapped and converted to chemical energy
in form of the bonds of glucose (C6H12O6)
3. Draw, label, and describe the function of a mitochondrion
Diagram
Functions
The most important function of mitochondria is to produce energy currency (ATP)
of the cell for various cellular action. As it is the site of three important steps of
cellular respiration which are as follows:
1. It is the site where pyruvate gets oxidized to acetyl co A
2. Acetyl CoA further get completely oxidized through TCA cycle to produce
CO2 and energy (NADH, FADH2, GTP) in mitochondria
3. It is the site of oxidative phosphorylation where members of electron
transport chain produce ATP using energized carrier like NADH and
FADH2 (which contribute maximum portion of ATP production in aerobic
cellular respiration).
The other functions are as follows:
1. Regulates the metabolic activity of the cell (as it is the major player for ATP
production)
2. Promotes the growth of new cells and cell multiplication (as for all anabolic
reaction cells need ATP)
3. Helps in detoxifying ammonia in the liver cells
4. Plays an important role in apoptosis or programmed cell death ( which kills
and remove the aged and diseased cells naturally)
5. Responsible for building certain parts of the blood and various hormones
like testosterone and oestrogen
6. Helps in maintaining an adequate concentration of calcium ions within the
compartments of the cell
7. It is also involved in various cellular activities like cellular differentiation,
cell signaling, cell senescence, controlling the cell cycle and also in cell
growth.
4. Write the equation for glycolysis. Compare the purpose of the first half (energy-
requiring steps) and second half (energy-harvesting steps) of glycolysis.
The final equation of glycolysis is as follows
Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 pyruvate + 2 NADH + 2 H+ + 2 ATP.
This can be categorized in to two steps: one is energy investing steps, which
converts glucose to fructose 1,6 bis phosphate, which further break down to two
molecules of glyceraldehyde 3 Phosphate
It can be written as
“Glucose+ 2ATP ----------2 glyceraldehyde 3 phosphate + 2ADP +2P”
These sets of reactions are important to increases the energy level of the reactants
(like glucose, fructose 6 phosphate), which make them unstable and ready to get
involved in splitting of the big molecule to the smaller ones (fructose 1,6,
bisphosphate to two molecules of glyceraldehyde 3 phosphate)
The second is energy harvesting step, in which two molecules of glyceraldehyde 3
Phosphate converted to 2 molecules of pyruvic acid, along with production of ATP
and energized carrier (NADH) as follows
“ 2 Glyceraldehyde 3 Phosphate +2NAD+ + 4ADP ----------2 pyruvate +2
NADH+ 2H+ + 4ATP
These sets of reactions are important to produce ATPs and NADH (NADH further
enters in oxidative phosphorylation to produce more ATPs in mitochondria)
5. Differentiate between cellular respiration and fermentation in terms of:
need for oxygen
organisms that use the pathways
number of ATP molecules generated by each
form of metabolism that evolved first.
Cellular respiration Fermentation
need for oxygen Needs oxygen No need of oxygen
organisms that use the Most of the organisms. Some bacteria, yeast
pathways Like many bacteria,
archaea, plants,
animals and fungi.
number of ATP 38 ATPs 2 ATPs
molecules generated by
each
Form of metabolism Evolved later Evolved first
that evolved first
6. Write the equation for glycolysis, beginning with glucose and ending with
pyruvate. Include the total ATP yield and electron carriers produced.
Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 pyruvate + 2 NADH + 2 H+ + 2 ATP.
Total ATP production: 4 ATPs, net ATP production 2 ATPs (as 2 get utilized in
the energy investment steps)
Electron carriers: 2 molecules of NADH
7. Identify which factors determine whether the pyruvate (pyruvic acid) produced
at the end of glycolysis will enter the alcoholic fermentation pathway, the lactate
(lactic acid) fermentation pathway, or the cellular respiration pathway.
Factors:
1. Availability of oxygen (it is the most important factor, presence of
oxygen promotes cellular respiration)
2. Type of respiration (machinery available for the organism, like some
bacteria don’t have the machinery to oxidize the pyruvate further),
3. Cellular energy level
8. Starting with pyruvate, recognize the equations for:
Lactate acid fermentation
Pyruvic acid + NADH --------->Lactic acid + NAD+
Reaction is catalyzed by enzyme: lactate dehydrogenase
Alcohol fermentation
It gets operated in two steps
1. Pyruvate ---------> Acetaldehyde +CO2
2. Acetaldehyde + NADH ---------> Alcohol (ethanol) + NAD+
So, in total
Pyruvate + NADH ---------> Alcohol + CO2 + NAD+
9. In cellular respiration:
Identify the reaction that occurs immediately after pyruvate enters the
mitochondria
Immediately after entry of pyruvate in mitochondria, it gets oxidized to
acetyl co A
The reaction is catalyzed by Pyruvate dehydrogenase complex (PDH)
pyruvate+ NAD+ + CoA-SH ---------> Acetyl CoA+ NADH + H+ +CO2
Identify the products of the Kreb’s Cycle (Citric Acid cycle)
Products of Krebs cycle when one molecule of Acetyl Co A enters in it
along with 3NAD+ + FAD + GDP + Pi and water are CoA-SH + 3NADH +
H+ + FADH2 + GTP + 2CO2
Identify the energized carriers that enter the electron transport chain.
Energized carrier: NADH, FADH2
10. Write the formula and location of these metabolic pathways:
Aerobic cellular respiration
The process take place in 4 steps, the steps and their respective locations are
as follows
Glycolysis: cytoplasm
Oxidation of pyruvic acid to acetyl Co A: mitochondria
TCA cycle: Mitochondria
Electron transport chain: mitochondria
Glycolysis
Location: cytoplasm
Formula
C6H12O6 + 2NAD+ +2ADP +2P-------2 pyruvate+ 2NADH+ 2H+ +2ATP
Oxidation of two pyruvates
Location: mitochondrial matrix
Formula
2pyruvate+ 2NAD+ + 2CoA-SH ---------> 2 Acetyl CoA+ 2NADH + 2H+
+2CO2
Krebs cycle (citric acid cycle)
Location: in mitochondria
Formula:
Acetyl-CoA + 3 NAD+ + FAD + GDP + P + 2H2O ------ CoA-SH +
3NADH + FADH2 + 3H+ + GTP + 2CO2
(you can multiply the number as per number of Acetyl co A given, the above
reaction is for one molecule of Acetyl CoA)
Combined pyruvate breakdown + Krebs cycle
Location: mitochondria
Formula:
Pyruvic acid+ 4NAD+ + FAD + GDP +Pi +2H2O ---------> 4NADH + 4 H+
+ FADH2 +GTP + 3CO2
11. Draw and label the process of chemiosmosis with regards to:
Location
ATP Synthase
H+ gradient
ADP/ATP
Sent separately
Both the diagrams I have taken from the internet let me know in
case you need any other assistance
