Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

F214 > 4. Respiration > Flashcards

4. Respiration Flashcards

0
Q

Outline the link reaction.

A

Occurs in the matrix of the mitochondria. Pyruvate is dehydrogenated and decarboxylated and converted to acetate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Outline glycolysis.

A

Can happen aerobically or anaerobic ally. A 6 carbon sugar (glucose) is broken down into 2, 3 carbon sugars (pyruvate).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Outline the Krebs cycle.

A

Takes place in the matrix of the mitochondria.
Citraline is decarboxylated and dehydrogenated.
Forms ATP, reduced NAD and reduced FAD.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Outline oxidative phosphorylation.

A

Takes place on the folded inner membrane (cristae) of mitochondria. This is where ADP is phosphorylated to ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why are coenzymes needed?

A

Many oxidation reactions occur in link and Krebs.
Although enzymes catalyse a wide range of metabolic reactions they struggle to catalyse oxidation and reduction reactions. Coenzymes are needed to help them catalyse oxidation/reduction.
NAD is a hydrogen carrying coenzyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe NAD

A

Organic non-protein.
Helps dehydrogenase enzymes carry out oxidation reactions.
Nicotinamide adenine dinucleotide (NAD).
2 linked nucleotides.
Base contains adenine as the nitrogenous base.
The other has a nicotinamide ring that can accept hydrogen atoms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe coenzyme A, structure and function.

A 
Made from 'pantothenic acid' adenosine (ribose + adenine) three phosphate groups and cysteine.
Carries ethanoate (acetate) from the link reaction to the Krebs cycle.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the stages of glycolysis?

A
  1. Phosphorylation
  2. Splitting hexose 1, 6 - bisphosphate.
  3. Oxidation of triose phosphate.
  4. Conversion of triose phosphate of pyruvate.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the ultrastructure of a mitochondrion.

A

All mitochondria have an inner and outer phospholipid membrane. These 2 membranes make up the envelope.
The inner membrane is folded into crisate
The two membranes enclose and separate the two compartments within mitochondria: the intermembrane space and the matrix.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the matrix of a mitochondrion.

A

The matrix is enclose by the inner membrane. It is semi rigid and gel like. Consisting of a mixture of proteins and lipids.
It also contains looped mitochondrial DNA, mitochondrial ribosomes and enzymes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the shape and size of a mitochondrion?

A

Between 0.5 - 1.0 micrometers in diameter.

2-5 micrometers long.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How might mitochondria distribution vary from person to person?

A

Athletes may have more mitochondria in metabolically active cells.
These mitochondria may have more densely packed cristae to house more electron transport chains and more ATP synthase enzymes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How might mitochondria move around cells?

A

Mitochondria can be moved around within cells by the cytoskeleton.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does the structure and composition of the matrix help it to carry out its functions?

A

The matrix is where the link reaction and Krebs cycle take place.
The matrix contains: enzymes which catalyse the stages of the reactions, molecules of co-e NAD, oxaloacetate (the 4c compound that accepts acetate from the link reaction, mitochondrial DNA which codes for mitochondrial enzymes and other proteins and mitochondrial ribosomes where these proteins are assembled.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does the structure of the outer membrane help it to carry out its functions?

A

Contains protein channels and carriers that allow the passage of molecules such as pyruvate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the structure of the inner membrane enable it to carry out its function?

A

Impermeable to small ions.
Folded into many cristae to gain a large surface area to assist diffusion.
Electron carriers and ATP synthase enzymes implanted into the membrane.
The electron carriers are protein complexes arranged in electron transport chains.
Each electron carrier is an enzyme. Each is associated with a co-factor. The cofactors are non protein groups. They are haem groups which contain an iron atom.
The cofactors can accept and donate electrons because the iron atoms can become reduced or oxidised. This makes the iron atoms oxidoreductive enzymes as they can oxidise or reduce.
Some of the electron carriers also have a coenzyme that pumps protons from the matrix into the intermembrane space.

16
Q

What are the stages of the link reaction?

A
  1. Pyruvate dehydrogenase removes hydrogen atoms from pyruvate.
  2. Pyruvate decarboxylase removes a carboxyl group, which eventually becomes CO2, from pyruvate to form acetate.
  3. The coenzyme NAD accepts the hydrogen atoms.
  4. Coenzyme A accepts the formed acetate to become acetyl coenzyme a which carries the acetate to the Krebs cycle.
17
Q

Describe the stages of the Krebs cycle.

A
  1. Acetate from the link reaction is off loaded from coenzyme A and joins with oxaloacetate, a 4 carbon compound, to form the 6 carbon compound citrate.
  2. The 6 carbon compound citrate is decarboxylated and dehydrogenated to form a 5 carbon compound and a molecule of CO2 and releasing a hydrogen atom to form a molecule of NAD.
  3. The 5 carbon compound is then decarboxylated and dehydrogenated to form a 4 carbon compound, a molecule of CO2 and releasing a hydrogen atom to reduce a molecule of NAD.
  4. The 4 carbon compound then undergoes substrate level phosphorylation in order to form one molecule of ATP.
  5. The second 4 carbon compound is dehydrogenated releasing a hydrogen atom which combines with another coenzyme FAD in order to form reduced FAD.
  6. The third 4 carbon compound is further dehydrogenated releasing a hydrogen atom which combines with NAD to form reduced NAD and regenerating the 4 carbon compound oxaloacetate.
18
Q

How many of each small molecule are released per molecule of glucose in the Krebs cycle?

A 
Each molecule forms 2 molecules of pyruvate in glycolysis and subsequently 2 molecules of acetate in the link reaction so the Krebs cycle occurs twice per molecule and so the overall numbers are:
6 molecules of NADH
2 molecules of FADH
2 molecules of ATP
4 molecules of CO2
Per glucose molecule.
19
Q

What other molecules can enter the Krebs cycle and how?

A

Fatty acids are broken down into acetates and can enter the Krebs cycle via coenzyme A.
Amino acids converted to keto acids can be used in respiration by being changed to either pyruvate or acetate depending on the amino acid.

20
Q

Describe the stages if oxidative phosphorylation.

A
  1. Reduced NAD is split away from its hydrogen atoms in the matrix of the mitochondria where they are split into electrons and protons.
  2. Complex 1 an electron carrier protein and proton pump accepts the electrons from NAD.
  3. Electrons flow across the electron transport chain (complex 1 -> 2 -> 3 -> 4) and small amounts of energy is released which is used to pump protons from the matrix into the intermembrane space. Only complexes 1,3 and 4 pump protons.
  4. The pumping of protons into the intermembrane space builds up a proton gradient, pH gradient and electrochemical gradient thus potential energy builds up in the intermembrane space.
  5. The protons cannot directly diffuse through the inner membrane but can diffuse through ion channels embedded in the membrane. These ion channels are associated with the enzyme ATP synthase. This flow of protons is chemiosmosis and powers the phosphorylation of ADP through the proton motive force.
  6. As the protons flow through the ATP synthase enzyme, they drive the rotation of part of the enzyme and join ADP and Pi to form ATP.
  7. The electrons pass from the final electron carrier (complex 4) to molecular oxygen as well as protons to form water. 4H+ + 4e- +O2 -> 2H2O.
21
Q

Per molecule of glucose, how much ATP could theoretically be produced? Why is this often not the case?

A

The 10 molecules of NAD that are produced across the entire aerobic respiration process (2 - glycolysis, 2 - link, 6 - Krebs) and from the molecules of ATP produced by substrate level phosphorylation (2-glycolysis, 2- krebs), 30 molecules of ATP could theoretically be produced.
This is not always the case as:
Some protons leak over the membrane and as such are not used as part of chemiosmosis to produce ATP.
Some ATP produced is used to actively transport pyruvate into the mitochondria.
Some ATP is used for the shuttle to bring hydrogen from reduced NAD made during glycolysis, in the cytoplasm, into the mitochondria.

22
Q

What happens if there is an oxygen deficit in the body?

A

Oxygen can no longer function as the final electron carrier so the electron transport chain can no longer take place and the link reactiom and Krebs cycle stop. Glycolysis produces small packets of ATP which can be used to sustain the organism for the duration of the adverse conditions.

23
Q

What is the problem with using the ATP produced from glycolysis?

A

In glycolysis NAD is required to act as an oxidising agent to allow substrate level phosphorylation to take place however as reduced NAD is not being regenerated into NAD due to the stoppage of oxidative phosphorylation only a limited amount of ATP can be produced.

24
Q

How does a eukaryotic organism lessen the impact of oxygen deficit?

A

A eukaryotic cell can use lactate fermentation to regenerate NAD to allow additional small amounts of ATP to be produced.
Pyruvate is the oxidising agent.
It accepts hydrogen atoms from reduced NAD.
NAD is nom deoxidised and is available to accept more hydrogen atoms from glucose.
Glycolysis can continue, generating enough ATP to sustain muscle contraction.
The enzyme lactate dehydrogenase catalyses the oxidation of reduced
NAD, together with the reduction of pyruvate to lactate.
The lactate is carried away from the respiring area in the blood to the liver.

25
Q

How can yeast cells produce ATP in anaerobic conditions?

A

Yeast cells can convert pyruvate into ethanal and then into ethanol using the enzymes pyruvate decarboxylase and ethanol dehydrogenase to form ethanol.

  1. Each pyruvate is carboxylated and forms a CO2 molecule and ethanal (this process is catalysed by pyruvate decarboxylase)
  2. Ethanal accepts hydrogen atoms from reduced NAD which becomes reoxidised as ethanal is reduced to ethanol (catalysed by ethanol dehydrogenase
  3. The reduced NAD can then be reused in glycolysis to accept more hydrogen atoms from glucose.
26
Q

What are some examples of respiratory substrates?

A
  1. Carbohydrates
  2. Proteins
  3. Lipids
27
Q

Where does the majority of the energy produced from respiration become?

A

Most energy is not used to produce ATP but rather is used to produce heat energy to maintain a constant body temperature.

28
Q

How can lipids enter the respiratory cycle?

A
  1. Triglyceride converted into glycerol and fatty acids
  2. Glycerol can be directly converted into glucose
  3. The fatty acids can be converted into Co enzyme - fatty acid by using ATP.
  4. Co-e ff can be converted into acetate which enters the Krebs cycle and reducing a molecule of NAD and FAD in the process.

F214 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions