Chapter 6 - Cellular Respiration Flashcards by Julia Armstrong

Do plants go through cellular respiration?

Yes, plants experience both photosynthesis and cellular respiration.

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What is the chemical equation for photosynthesis and cellular respiration?

Photosynthesis:
Light energy +6CO2 + 6H2O —–> C6H12O6 + 6O2
Respiration:
C6H12O6 + 6O2 —–> 6CO2 + 6H2O + Energy (ATP + heat)

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Can energy be recycled? Can chemicals from cellular respiration be recycled?

No, energy makes a one-way trip through an ecosystem.
Yes, chemicals are recycled.

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What organelle does cellular respiration take place in?

Mitochondria 🔥THE POWERHOUSE OF THE CELL️‍🔥 (and glycolysis in the cytoplasm)

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Define cellular respiration.

The oxygen requiring harvesting of energy from food molecules by cells.

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Is cellular respiration and breathing the same thing? Explain.

No, but they are related. Breathing supplies the oxygen (via blood) and disposed of the CO2 necessary for cellular respiration.

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What is a kilocalorie (kcal)? What do we measure in kilocalories?

The amount of heat required to raise the temperature of 1 kg of water by 1 degree celsius. Can be used to measure energy in food or how much energy certain activities use up.

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What is the energy staircase?

Cellular respiration can be described as a controlled descent of electrons down an energy staircase (from glucose to oxygen), with small amounts of energy being released at various steps

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What are REDOX reactions? Example?

Chemical reactions that involve a transfer of electrons.
One reactant is reduced while the other is oxidized, (one does not happen without the other).
i.e. Cellular respiration.

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What does the acronym OIL RIG mean?
How are hydrogen atoms related to this?

Oxidation Is Losing electrons;
Reduction Is Gaining electrons.
We can generally follow these electrons by seeing where their associated protons (H) end up.
Hydrogen = electrons

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What is NAD+ and what is its primary function in cellular respiration? What is it reduced to? Where does this fit in the energy staircase?

NAD+ is a coenzyme that cells make from the vitamin niacin. It is used to shuttle electrons (two at a time) in redox reactions, becoming reduced to NADH + H+
The first step.

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What is FAD? What does it reduce to?

An electron acceptor, not nearly as abundant as NAD+, also carries/transfers 2 electrons.
FAD is reduced to FADH2

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What’s the difference between ATP and NADH + H+ (in terms of energy)?

ATP is readily usable energy.
The energy stored in the NADH + H+ is potential energy that will be used in oxidative phosphorylation to generate a lot more ATP.

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______ is the final electron acceptor in cellular respiration.

Oxygen.

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What are the key steps of cellular respiration (3)?

Glycolysis, the Citric Acid Cycle, and Oxidative Phosphorylation (+mini step between glycolysis and the Citric Acid cycle)

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What steps of cellular respiration occur in all cells?

Glycolysis occurs in the cytoplasm of ALL cells, plant, animal, bacterial, etc.

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What do aerobic and anaerobic mean? What step of cellular respiration is anaerobic?

Aerobic = with oxygen.
Anaerobic = without oxygen.
Glycolysis is anaerobic.

Where in the cell does glycolysis occur? What substrate does it start with and what is produced at the end?

Glycolysis occurs in the cytoplasm (liquid interior) of the cell. One 6C glucose molecule becomes 2 3C molecules (pyruvate)
Produces 2 ATP and reduces 2NAD+ to 2NADH + 2H+

How many steps does glycolysis actually have? How much ATP is used and produced by glycolysis?

9 steps split into two stages:
- 4 steps turn 6C glucose into 2 3C molecules of G3P
- 5 steps turn G3P into 2 3C pyruvate
2 ATP are invested; 4 are produced for a net gain of 2 ATP.

What happens to the products of glycolysis before the citric acid cycle? How many NAD are used here?

The pyruvate (2 3C) enters the mitochondrial matrix and is oxidized to become Acetyl Co-enzyme A (2 2C, Acetyl CoA) + 2 CO2.
One NADH + H+ is made per pyruvate (so 2 more NADH + H+ per glucose)

Where does the citric acid cycle occur?

In the mitochondrial matrix/ within the inner membrane of the mitochondrion (cristae/folds).

During the Citric Acid Cycle, how many NAD+ and FAD are reduced?
How many ATP are made per Acetyl CoA? What does the Acetyl-CoA become? What is produced per glucose molecule?

3 NAD are reduced to 3NADH + 3H+, one FAD is reduced to FADH2 and 1 ATP is produced per Acetyl-CoA.
One Acetyl-CoA becomes 2 CO2.
2 Acetyl-CoA are made per glucose so 2 ATP, 6 NADH + 6 H+ and 2 FADH2 are produced (and 4 CO2).

Which substance is regenerated in the citric acid cycle which makes it a cycle.

4C Oxaloacetate
It joins with the 2C Acetyl Co-A at the beginning and is regenerated by the end of the cycle.

What is chemiosmosis? How is it related to ADP/ATP?

An energy coupling mechanism that uses the energy of hydrogen ion gradients across membranes to drive cellular work, such as the phosphorylation of ADP to ATP.

What are the net products of glycolysis and the citric acid cycle from one molecule of glucose?

4 ATP, 10 NADH + 10 H+ and 2 FADH2.

Does the citric acid cycle consume oxygen?

No oxygen is consumed in this cycle. (But also it is a process that cannot occur without the presence of oxygen. idk why)

By the end of the citric acid cycle, how many electrons are available to enter the electron transport chain during oxidative phosphorylation?

24 electrons/hydrogen. These are from the 10 NADH + 10 H+ and 2 FADH2 that have been produced so far.

Where in the mitochondrion does oxidative phosphorylation take place? What are the two parts of this process?

Entirely within the inner membrane (cristae/folds) of the mitochondrion. The electron transport chain and chemiosmosis.

Three transmembrane carrier protein complexes in the electron transport chain actively pump H+ across the membrane from where it is _______ concentrated in the ________ ________ to where it is ______ concentrated in the ________ _______. Where does the energy required for this come from?

Less concentrated (in the mitochondrial matrix) to where it is more concentrated (in the intermembrane space). The energy required for this is in the exergonic process of electrons “falling” towards oxygen.

Why is it important that the inner membrane of the mitochondrion is highly folded into cristae?

This dramatically increases the surface area of the inner membrane, which makes space for many copies of the enzymes.

Hydrogen ions fall down their concentration gradient through a particular enzyme. What is it called and what does it do? Where does the hydrogen fall from and to?

ATP synthase (like a turbine!). It is used to add a phosphate group to (aka. phosphorylate) ADP to make ATP. Hydrogen falls from the intermembrane space to the matrix.

What are the products of oxidative phosphorylation?

About 28 more ATP are made and oxygen is reduced to water.

How many ATP can be produced every second in a working muscle cell?

10 million!!!

In cellular respiration, how much ATP is made by substrate-level phosphorylation compared with oxidative phosphorylation?

4 ATP are made by substrate-level phosphorylation during glycolysis and the citric acid cycle. About 28 ATP are made by oxidative phosphorylation.

If there were no oxygen for electrons to fall to, how would this affect the ability of cells to produce ATP?

The whole system would back up and the majority of the ATP production would stop. This would starve your cells of energy.

How can things like carbon monoxide and poisons interrupt cellular respiration? What are uncouplers?

CO stops the flow of electrons, no H+ is pumped and no ATP can be made. Poisons, called uncouplers, work by making the membrane leaky to H+ ions so the gradient is destroyed.

Other than glucose, what can enter cellular respiration to create energy?

**Starches and glycogen** can be broken down into glucose, **fats** are broken into glycerol that enters glycolysis as (G3P) and fatty acid chains are broken into 2 carbon fragments that enter the citric acid cycle as acetyl Co-A.

The first prokaryotes evolved in the absence of oxygen – so how did they obtain energy?

They got energy from glycolysis alone and there are still many prokaryotic organisms that are still capable of living anaerobically.

How does NADH + H+ get oxidized back to NAD if there is no oxygen? What are two examples?

Fermentation ☺ NADH + H+ becomes oxidized again by reducing pyruvate to either lactate or ethanol. Lactic acid (muscles, yogurt, cheese) and alcohol fermentation (bread, wine, beer)

What are facultative anaerobes? What are obligate anaerobes?

FA: make ATP by fermentation or oxidative phosphorylation, depending on if oxygen is available. OA: Require anaerobic conditions to survive. Oxygen is toxic to them.

Why will a facultative anaerobe prefer to use oxidative phosphorylation to make ATP instead of fermentation?

Oxidative phosphorylation releases far more ATP (28 ATP instead of 2 from just glycolysis).

How do bacteria carry out the citric acid cycle and oxidative phosphorylation without mitochondria?

Citric acid cycle occurs within the cytoplasm of the cell. OP uses the plasma membrane and creates an H+ concentration outside the cell which falls back inside.