Cellular Respiration Flashcards
Is Cellular Respiration Endergonic or Exergonic and why
It is exergonic because it releases energy
Where does Cellular respiration take place
In the mitochondria of eukaryotic cells
What actually happens in cellular respiration
Glucose is broken down to carbon dioxide and water and the cell captures SOME of the released energy to make ATP
in other words: a process that transfers energy from the bonds in glucose to form ATP
Respiration vs Cellular Respiration
Although the two relate, they are not the same.
Respiration is when an organism brings in oxygen from the environment and releases Carbon Dioxide (CO2).
Cellular respiration uses that oxygen
In other words: Breathing happens in order to do cellular respiration
How much ATP is produced from each glucose molecule in cellular respiration
28 - 32 ATP molecules (usually closer to 32)
What percent of energy originally stored in the glucose is captured in cellular respiration
About 34%
Why not just have one chemical reaction that releases all of the energy from the glucose molecule?
If there was just one reaction that went very fast, the energy would burn and we wouldn’t be able to use it. However, with the slow process that gradually releases energy in small amounts (stored in the form of ATP), this is avoided.
Redox Reaction
The movement of electrons from one molecule to another
Reduction (in redox reaction)
The ADDITION of electrons to a substance
that substance gains electrons and therefor gains energy, but in terms of charge, it goes down (because electrons are negatively charged)
Oxidation (in redox reaction)
The LOSS of electrons from a substance
Oxygen “Steals” electrons from them
That substance loses electrons and therefor loses energy, but in terms of charge, it goes up (because electrons are negatively charged)
Cellular respiration equation
Glucose loses its hydrogen atoms (and electrons) and becomes oxidized to CO2 (carbon dioxide)
Oxygen gains hydrogen atoms (and electrons) and becomes reduced to H2O (water)
NAD+
- is an important enzyme in oxidizing glucose
- accepts electrons
- becomes reduced to NADH
4 Stages of Cellular Respiration (in order)
Stage 1 - Glycolysis
Stage 2 - Pyruvate Oxidation
Stage 3 - Citric Acid Cycle
Stage 4 - Oxidative Phosphorylation
Cellular Respiration Equation
Where does Glycolysis occur? What goes in and what comes out in Glycylosis?
Occurs in Cytoplasm
GOES IN: 1 Glucose (2 ATP)
COMES OUT: 2 Pyruvate, 4 ATP (net 2 ATP because 2 in, 4 out), and 2 NADH
Where does Pyruvate Oxidation (grooming) occur? What goes in and what comes out in Pyruvate Oxidation?
Occurs while pyruvate molecules are entering mitochondria
GOES IN: 2 Pyruvate
COMES OUT: 2 AcetylCoA, 2 NADH, 2 CO2
Where does Citric Acid Cycle occur? What goes in and what comes out in Citric Acid Cycle?
Occurs in the Matrix (center of the mitochondria)
GOES IN: 2 AcetylCoA
COMES OUT: 6 NADH, 2 FADH2, 2 ATP, 4 CO2
Where does Oxidative Phosphorylation (ETC) occur? What goes in and what comes out in Oxidative Phosphorylation (ETC)?
Occurs in the inner membrane of the mitochondria
GOES IN: 10NADH, 2FADH2 (sub 2)
COMES OUT: about 28 ATP molecules
What are the two types of Phosphorylation that occur in cellular respiration and when do they occur?
- Substrate-level phosphorylation (occurs in glycolysis and the citric acid cycle)
- Oxidative phosphorylation (occurs in Oxidative Phosphorylation also known as ETC)
Explain Substrate-Level Phosphorylation
An enzyme transfers a phosphate group from a substrate molecule to ADP, ultimately forming ATP
What are the two main phases of glycolysis
- The energy investment phase
- The energy payoff phase
What happens in the energy investment phase of Glycolysis?
- energy consumed as two ATP molecules is used to energize a glucose molecule
What happens in the energy payoff phase of Glycolysis?
- 4 ATP molecules are generated (net 2 because 2 were consumed in energy investment phase)
What happens to the pyruvate formed in glycolysis?
it is transported from the cytoplasm into a mitochondria where the citric acid cycle and oxidative phosphorylation will occur (this all happens through pyruvate oxidation)
how many molecules of pyruvate are produced for each molecule of glucose that enter glycolysis?
2
What is Cellular Respiration
the process by which organisms use oxygen to break down food molecules to get chemical energy for cell functions
How many molecules of AcetylCoA are processed for each initial glucose in the citric acid cycle?
2
What happens during oxidative phosphorylation?
- electrons from NADH and FADH2 travel down the electron transport chain to O2 (oxygen)
- Oxygen picks up H+ to form water
- energy released by these redox reactions is used to pump H+ from the mitochondrial matrix into the intermembrane space
- in chemiosmosis, the H+ diffuses back across the inner membrane through ATP synthase complexes, driving the synthesis of ATP
ATP Synthase
An enzyme and channel that allows for the facilitated diffusion of H+ back into the matrix of a mitochondria after being pumped out (chemiosmosis). The H+ make the ATP Synthase spin which ultimately leads to the creation of ATP.
Chemiosmosis
The facilitated diffusion of protons through the ATP Synthase
How much ATP can 1 NADH produce?
3 ATP Molecules
What stage of cellular respiration evolved first?
Glycolysis
Evidence:
doesn’t need mitochondria
glycolysis doesn’t need oxygen to happen
What stage of cellular respiration evolved last?
Pyruvate Oxidation
Evidence:
step in between one and another (why would it be created if there was nothing yet to connect)
varies from one organism to another
How many times do you have to run pyruvate oxidation per each glucose molecule that goes through cellular respiration?
two because there are two three carbon pyruvate for every one 6 carbon glucose
Why is the citric acid cycle a cycle?
The starting molecule is re-generated by the end of the cycle (but through the cycle ATP is produced and CO2 leaves)
there is no more of the original glucose by the end of the citric acid cycle
What happens to the electron transported in the steps of ETC (during the process and after)
it loses energy through each time being transported and it get’s picked up at the end by oxygen to form water
Where is the remaining energy from the electron that goes through ETC held?
in the concentration gradient
Which electron carrier’s electron’s are more charged by the end ETC and why?
FADH2 electrons are more charged than the NADH electrons by the end of ETC because they go through one less protein
Why do you need oxygen for ETC?
it picks up the electron after it is transported through all of the proteins, MAKING THOSE ELECTRON CARRIERS NOW EMPTY AND ABLE FOR REUSE
Why is the Inner mitochondrial membrane folded?
Folds maximize the surface area upon which the process of oxidative phosphorylation occurs
AND, more membrane = more ATP produced
what are Cellular poisons? What are the three categories of them?
Cellular poisons obstruct the process of oxidative phosphorylation
Three categories:
- ones that Block the electron transport chain
- ones that inhibit ATP synthase
- ones that make the membrane leaky to hydrogen ions
What is Fermentation
and what specifically does it do
Fermentation is a way of harvesting chemical energy that does not require oxygen
Fermentation…
- takes advantage of glycolysis
- produces two ATP molecules per glucose
- reduces NAD+ to NADH
What are the two types of fermentation
- Lactic acid fermentation
- alcohol fermentation
What happens in lactic acid fermentation
- NADH is oxidized to NAD+
- Pyruvate is reduced to lactate
What happens in alcohol fermentation
- NADH is oxidized to NAD+
- Pyruvate is converted to CO2 and ethanol (releases the CO2)
Obligate anaerobes
- poisoned by oxygen (dies in presence of oxygen)
- live in stagnant ponds and deep soils
Facultative anaerobes
- Can make ATP by fermentation OR oxidative phosphorylation
- include yeasts and many bacteria
What is the most direct energy source that powers the making of ATP by Oxidative Phosphorylation?
The facilitated diffusion of the protons, the concentration gradient of the protons,
PROTON MOTIVE FORCE
Could Oxidative phosphorylation work without oxygen? if there was no oxygen, how would that also affect the rest of cellular respiration (besides oxidative phosphorylation)?
- no it could not because the electrons can’t be dropped off to bind with anything at the end (usually binds to oxygen to make water)
- it wouldn’t work because to start glycolysis you need empty electron carriers (all of the electrons carriers would be full but with nothing to drop their electrons off too (usually oxygen)
Anabolic vs Catabolic reactions
AND
is cellular respiration anabolic or catabolic
Anabolic reactions use energy to build complex molecules from simpler organic compounds
Catabolic reactions break complex molecules down into simpler ones, releasing chemical energy
Cellular respiration is CATABOLIC because it breaks down glucose to make energy
aerobe
requires oxygen, performs cellular respiration
anaerobe
does not require oxygen, performs fermentation
Example(s) of simple diffusion in cellular respiration
carbon dioxide leaving the cell (after cellular respiration)
oxygen coming in (for cellular respiration)
Example(s) of facilitated diffusion in cellular respiration
Chemiosmosis - facilitated diffusion of H+ ions through the ATP synthase
Example(s) of active transport in cellular respiration
active transport of H+ ions (protons) moving against the concentrations gradient into the intermembrane space through the ETC proteins
Example(s) of osmosis in cellular respiration
Water leaving the cell (after cellular respiration)
(NOT SPECIFIC TO THIS UNIT)
Phosphofructokinase
an enzyme in glycolysis that gets regulated:
inhibited by (excess) ATP and Citrate (telling PFK to slow down) when there is already enough ATP in the cell or organism (for now)
stimulated by AMP (tells PFK to speed up) when the cell or organism is depleted and it needs more ATP
This is all done as FEEDBACK INHIBITION (ATP inhibits something in the process that made it)
Levels of energy storage
ATP
Glucose
Glycogen
Fat
(fat most long term, ATP most short term)
What is the only type of macromolecules that does all of the steps in cellular respiration?
Carbohydrates (sugars)
Do Proteins (amino acids) go through all of glycolysis? if not where can they skip to?
NO
can skip many steps, most they can skip is up to the citric acid cycle
do Fats (glycerol and fatty acids) go through all of glycolysis? if not where can they skip to?
NO
glycerol skips to glyceraldehyde 3-p (we don’t need to know that, just comprehend)
Fatty acids skip to (turn into) Acetyl CoA
AMP
used up ATP
has less energy than ADP which has less energy than ATP
Endosymbiotic theory
the mitochondria and chloroplast in a eukaryote was once a prokaryote that got engulfed by a larger cell
Evidence for Endosymbiotic theory
- mitochondria has double membrane
- mitochondria replicate on their own (without rest of cell)
- mitochondria have their own DNA and Rybosome
- produce their own protiens
Independant variable in lab
state of the seed (germinated vs nongerminated)
dependent variable in lab
The CO2 concentration in the jar
