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A Level Biology Paper 2 > Section 5 - Chapter 12: Respiration - old > Flashcards

Section 5 - Chapter 12: Respiration - old Flashcards

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1
Q

What are the 4 stages of aerobic respiration

A
  • Glycolysis
  • Link reaction
  • Krebs Cycle
  • Oxidative phosphorylation
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2
Q

What are coenzymes

A
  • A co-enzyme is a molecule that aids the function of an enzyme by transferring a chemical group from 1 molecule to another
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3
Q

What are examples of co-enzymes in respiration and what do they do

A
  • NAD, Co-enzyme A and FAD
  • NAD and FAD transfer hydrogen
  • Co-enzyme A transfers acetate between molecules
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4
Q

What are the 2 different forms of cellular respiration

A
  • Aerobic Respiration
  • Anaerobic Respiration
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5
Q

What does Aerobic Respiration and Anaerobic Respiration produce

A
  • Aerobic: CO2, Water and a lot of ATP
  • Anaerobic: lactate (animals), ethanol and CO2 (plants/fungi) and a little bit of ATP
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6
Q

What happens in Glycolysis and what is the overall product?

A
  • Splitting of a 6-carbon glucose molecule into 2 3-carbon pyruvate molecules
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7
Q

What happens in the Link Reaction and what are the overall products

A
  • The 3-carbon pyruvate molecules enter into a series of reactions which lead to the formation of acetyl co-enzyme A (2-carbon molecule)
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8
Q

What happens in the Krebs Cycle and what are the overall products

A
  • Acetyl Co-enzyme A goes into a series of oxidation-reduction reactions that yield some ATP and lots of reduced NAD and FAD
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9
Q

What happens in Oxidative Phosphorylation and what are the overall products

A
  • The use of electrons, associated with reduced NAD and FAD synthesise ATP with water produced as a by-product
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10
Q

What are the 2 main stages in Glycolysis

A
  • Phosphorylation
  • Oxidation
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11
Q

What happens in Phosphorylation in Glycolysis

A
  1. Glucose is phosphorylated using a phosphate from ATP to create Glucose Phosphate and 1 ADP
  2. ATP is used to add a phosphate to Glucose Phosphate to make Hexose Biphosphate
  3. Each phosphorylated glucose molecule is split into 2 3-carbon Triose Phosphate
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12
Q

What happens in Oxidation in Glycolysis

A
  1. Hydrogen is removed from both Triose Phosphate molecules.
  2. Hydrogens are transferred to NAD to form 2 reduced NAD
  3. Enzyme controlled reactions convert each TP molecule in Pyruvate. (2 ATP produced - 4 in total)
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13
Q

What are the products if Glycolysis and what are their uses

A
  • 2 NADH - goes to oxidative phosphorylation
  • 2 Pyruvate - Actively transported into mitochondrial matrix for link reaction
  • 2 ATP - used for energy
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14
Q

Where are the enzymes for Glycolysis found and what does this mean

A
  • Found in the cytoplasm (takes place in cytoplasm)
  • Glycolysis doesn’t require any organelle or membrane to take place
  • It doesn’t require oxygen
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15
Q

What happens in the Link Reaction

A
  1. Pyruvate molecules are actively transported into the matrix of the mitochondria
  2. Pyruvate (3C) is oxidised to acetate (2 C). 1 CO2 and 2 hydrogens (forms NADH) released for 1 pyruvate
  3. The 2C acetate combines with co-enzyme A to produce acetyl coenzyme A
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16
Q

What are the products of the Link reaction and where do they go

A
  • 2 Acetyl co-enzyme A - To the Krebs Cycle
  • 2CO2 - Released as a waste product
  • 2NADH - To oxidative phosphorylation
17
Q

What are the main stages of the Krebs Cycle of Respiration

A
  1. Formation of a 6C compound
  2. Formation of a 5C compound
  3. Regeneration of Oxaloacetate
18
Q

What happens in the Formation of a 6C compound in the Krebs Cycle

A
  • The 2C acetyl CoA (from link reaction) combines with a 4C molecule (Oxaloacetate) to form a 6C compound Citrate.
  • Co-enzyme A goes back to the link reaction to be used again.
19
Q

What happens in the Formation of a 5C compound part of the Krebs Cycle

A
  • In a series of reactions. Citrate is converted into a 5C compound
  • Decarboxylation occurs 1 CO2 is removed
  • Dehydrogenation occurs. Hydrogen is removed and forms NADH
20
Q

What happens in the Regeneration of Oxaloacetate part of the Krebs Cycle

A
  • The 5C compound turns into a 4C compound
  • Decarboxylation and Dehydrogenation occurs and produces 1 ATP - substrate-level phosphorylation
  • Produces 1 FADH, 2 NADH
21
Q

What are the products of the Krebs Cycle and what are their uses

A
  • 1 co-enzyme A - reused in the next link reaction
  • Oxaloacetate - Regenerated for the use in the next Krebs Cycle
  • 2CO2 - waste
  • 1 ATP - energy
  • 3 NADH and 1 FADH - oxidative phosphorylation
22
Q

What is the importance of the Krebs Cycle

A
  • Breaks down macromolecules into smaller ones - pyruvate broken into CO2
  • Produces hydrogen atoms that are carried by NAD to electron transfer chain and provide energy for OP. This produces ATP
  • It regenerates Oxaloacetate that combines with acetylcoenzyme A which would accumulate
  • Is a source of intermediate compounds used by cells to manufacture substances like fatty acids, amino acids and chlorophyll.
23
Q

Practical:

  1. What happens when you add hydrogen atoms to methylene blue
    2) Why use a control tube
A
  1. Becomes reduced methylene blue (colourless)
  2. Show that the yeast was responsible for the colour change (glucose didn’t change methylene blue/ didn’t change by itself)
24
Q

Tube A has yeast, glucose and methylene blue - colourless

Tube C has yeast, water, methylene blue - pale blue

Suggest explanation for the colours

A
  1. Yeast uses glucose as a respiratory substrate producing hydrogen - taken up by methylene
  2. Yeast uses stored carbohydrate as a respiratory substrate that has to be converted to glucose so the production of hydrogen is slower
25
Q

How might the results in tube A after 15 minutes been different if carried out at different temperature 60°c

A
  • Remained this because enzymes involved in respiration are denatured at 60°c
26
Q

After 20 minutes tube A was mixed vigorously turning methylene blue again. How

A
  • Air contains oxygen which would reoxidise methylene blue so it is blue
27
Q

What is the process of the electron chain in OP

A
  1. Hydrogen atoms are released from NADH and FADH . They split into protons and electrons
  2. Electrons move down ETC in a series of oxidation-reduction reactions. As they flow the energy they release causes active transport of protons across mitochondrial membrane into the inner membranal space
  3. Protons accumulate in the inter membranal space they move into mitochondrial matrix via ATP synthase. The movement drives the synthesis of ATP
  4. In the mitochondrial matrix at the end of ETC. Protons, electrons and oxygen from blood combine to form water. Oxygen is the final acceptor
28
Q

How are lipids used as a respiratory substrate

A
  • Before being respired, lipids are first hydrolysed to glycerol and fatty acids
  • Glycerol is phosphorylated and converted to triose phosphate which enters glycolysis
  • Fatty acid is broken down 2-carbon fragment which are converted into acetyl coenzyme A
  • Hydrogen atoms are released
29
Q

How are proteins used as a respiratory substrate

A
  • It is first hydrolysed to amino acids.
  • They have their amino group removed before entering the respiratory pathway at different points depending on the number of carbon atoms.
    • 3 carbon compounds - pyruvate
    • 4/5 converted to intermediates in the Krebs Cycle.
30
Q

What happens when there is an absence of oxygen

A
  • Neither the Krebs cycle nor ETC can continue as all FAD and NAD will reduce
  • NO FAD or NAD will take up H+ from Krebs so enzymes will stop working
  • Leaves only glycolysis
31
Q

What do the 2 ways in Eukaryotic cells during anaerobic respiration produce

A
  1. In plants and yeast the pyruvate is converted into ethanol and CO2
  2. In animals the pyruvate is converted to lactate
32
Q

What happens in anaerobic respiration with plants/yeast

A
  • The pyruvate molecule formed at the end of glycolysis loses a molecule of carbon dioxide to produce ethanal
  • This accepts hydrogen from reduced NAD to produce ethanol.
33
Q

What happens in anaerobic respiration in animals

A
  • Produces lactate in means of overcoming a temporary shortage of oxygen
  • Lactate production occurs in muscles exercise may cause oxygen debt.
  • NAD can accumulate and must be removed therefore each pyruvate takes up 2 hydrogen atoms from NADH to form lactate.
34
Q

What happens to the lactate when there is oxygen again

A
  • Lactate is oxidised to pyruvate
  • This can be further oxidised to release energy or converted to glycogen
  • Lactate can cause muscle cramp. Lactate is an acid - cause pH changes (enzymes)
35
Q

Energy from cellular respiration is derived from 2 ways

A
  • Substrate-Level Phosphorylation: in Glycolysis and the Krebs Cycle. This is the direct transfer of a phosphate from a respiratory intermediate to ADP
  • Oxidative Phosphorylation: In the ETC. Involving energy of the hydrogen atoms from NAD/FAD.
36
Q

In anaerobic respiration how is ATP formed

A
  • Pyruvate is converted to either ethanol or lactate. Not available for the Krebs Cycle or ETC.
  • Only ATP produced is from the Glycolysis stage

A Level Biology Paper 2 (10 decks)

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