Brainscape's Knowledge GenomeTM

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


See full index

OCR Biology A Level Module 5 Communication, homeostasis and energy > 5.7 Respiration > Flashcards

5.7 Respiration Flashcards

1
Q

What is the need for respiration?

A
  • release energy stored in organic molecules which is used to synthesise ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is ATP used for?

A
  • hydrolysed to release a small quantity of energy for use in cells -> no damage or waste
  • drive processes such as transport, protein synthesis, DNA replication, cell division, movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the structure of ATP? Is it stable in solution?

A
  • adenine, ribose, 3 phosphates (phosphoanhydride bonds)
  • stable in solution but is readily hydrolysed by enzyme catalysis.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are mitochondria adapted to perform their function?

A
  • inner membrane: less permeable to smaller ions. CRISTAE gives large SA for electron carriers + enzymes such as the ATP synthase stalked particles.
  • outer membrane allows pyruvate in for example
  • inner + outer = envelope
  • intermembrane space involved in oxidative phosphorylation
  • matrix -> contains enzymes, NAD, FAD, oxaloacetate, DNA, ribosomes.
  • ETC: electron carrier proteins are oxido-reductase enzymes -> iron ions are cofactors and can accept and donate electrons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain the process of glycolysis

A
  1. Glucose is activated via phosphorylation. 2 ATPS are hydrolysed into 2ADP and 2 phosphates and energy is released, preventing transport out of the cell. This results in hexose bisphosphate which is unstable.
  2. Each 6 carbon molecule is split into two TP molecules.
  3. Oxidation of the TP’s occurs, where NAD coenzymes accept hydrogens to become reduced NAD
  4. Substrate-level phosphorylation also forms 2ATP per TP.
  5. This forms two pyruvate molecules per molecule of glucose. Net gain 2ATP. Two reduced NAD.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where does glycolysis happen?

A
  • cytoplasm of the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is NAD? What is its role? What is it synthesised from?

A
  • non-protein coenzyme
  • oxidation of substrate
  • synthesised from nicotinamide (B3 vitamin), ribose, adenine, and 2 phosphates.
  • carries protons and electrons to cristae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where does the link reaction and Krebs cycle take place?

A

the mitochondrial matrix

will not occur in absence of oxygen

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

Describe the process of the link reaction. What are the products?

A
  • each pyruvate is decarboxylated and dehydrogenated (NAD becomes reduced NAD), catalysed by pyruvate dehydrogenase.
  • CoA then binds, forming acetyl CoA.
  • NO ATP, 2xCO2 and 2 NADH for EACH GLUCOSE.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the Krebs cycle

A
  1. formation of citrate from the acetyl group of acetyl CoA and oxaloacetate (CoA is released and reused in link reaction)
  2. citrate is decarboxylated and dehydrogenated (NAD -> NADH), forming a 5C compound
  3. this 5C compound is decarboxylated and dehydrogenated also (NAD -> NADH)
  4. the resulting 4C compound combines temporarily with and is released from coenzyme A
  5. substrate phosphorylation occurs, forming 1 ATP and a different 4C compound
  6. this compound is dehydrogenated, reducing FAD to FADH2 this time.
  7. this compound is dehydrogenated also (NAD -> NADH), catalysed by an isomerase enzyme, reforming oxaloacetate.

products: for EACH GLUCOSE there is 2 turns. therefore 4 CO2 is produced, 2 ATP, 2 FADH2, and 6 NADH

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

How is pyruvate transported into the matrix?

A
  • pyruvate H+ symport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where does oxidative phosphorylation occur?

A

matrix, cristae and intermembrane space

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

Describe the process of oxidative phosphorylation, including the chemiosmotic theory

A
  1. reduced NAD and reduced FAD are reoxidised, releasing 2 hydrogens for each coenzyme.
  2. these 2 hydrogens are split into 2 electrons and 2 H+ ions.
  3. the electrons travel down the electron transport chain through proteins containing an iron ion co factor, through a series of redox reactions.
  4. Hydrogen ions are pumped from the matrix to the intermembrane space using energy transferred by these electrons.
  5. this establishes an electrochemical gradient and proton-motive force, causing the H+ ions to diffuse down through the stalked particle and ATP synthase = CHEMIOSMOSIS
  6. ADP + Pi -> ATP
  7. 4 electrons, 4 H+ ions and oxygen from the blood are combined to form 2 water molecules . oxygen acts as the FINAL ELECTRON ACCEPTOR.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How many NADH and FADH2 are made in respiration?

A
  • 10 NADH and 2FADH2
  • these then convert to 10NAD and 2FAD during oxidative phosphorylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens if O2 isnt present?

A
  • cannot act as final electron acceptor
  • [protons] in matrix increases and oxidative phosphorylation ceases
  • reduced NAD cannot be reoxidised
  • Krebs cycle stops
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the 2 pathways by which anaerobic respiration can occur?

A

lactate fermentation (mammals) and ethanol fermentation (fungi and plants)

17
Q

What occurs during ethanol fermentation? What enzyme catalyses this?

A
  1. pyruvate is decarboxylated to form ethanal
  2. ethanal is then hydrogenated ( NADH + H+ becomes NAD+) to form ethanol. This is catalysed by ethanol dehydrogenase.
  3. NAD + is then reused in glycolysis.
18
Q

What occurs during lactate fermentation?

A
  • pyruvate is hydrogenated (oxidation of NADH), to form lactate. Catalysed by lactate dehydrogenase
19
Q

What happens to lactate?

A
  • if lactic acid were formed this would inhibit enzymes, so it is carried to the liver to be converted to pyruvate and enter Krebs, or recycled to glucose and glycogen.
20
Q

What are respiratory substrates?

A
  • organic substances that can be oxidised in respiration, releasing energy to make ATP
21
Q

How can carbohydrates other than glucose be used in respiration?

A
  • disaccharides can be digested to monosaccharides
  • these can be changed by isomerase enzymes to glucose
  • glycogen and starch can be hydrolysed to glucose
22
Q

Fatty acids and amino acids can only be respired ………

A

aerobically

23
Q

What are the mean energy values for carbs, lipids and proteins?

A

CARBS: 15.8
LIPID: 39.4
PROTEIN: 17.0

24
Q

Why do lipids have a higher mean energy value?

A
  • higher proportion of H atoms
  • more NADH
  • more protons for chemiosmosis
  • more ATP
  • more O2 also needed
25
Q

How do you calculate Rq? What are the values you must memorise?

A

CO2 produced/ O2 consumed
Carb: 1
Fatty Acid: 0.7
Amino Acid: 0.8-0.9
Greater than 1 = anaerobic = glucose.

26
Q

Which applies to NAD or FAD?

  1. Is a prosthetic group
  2. Is reduced in the link reaction
  3. Oxidises molecules in ETC
A
  1. FAD
  2. NAD
  3. NEITHER
27
Q

A teacher told his students that the human body makes the equivalent of its own mass in
ATP every day.
Explain why, at the end of the day, only a small proportion of the students’ mass was
ATP.

A

because ATP is , broken down / hydrolysed (to ADP) 
ATP is constantly recycled 
ATP used to provide energy for , (named) metabolic reactions / processes 
ATP is , not stored long term / used immediately 

28
Q

Explain why early eukaryotes were able to grow more quickly than cells that did not
possess mitochondria.

A

1 would be able to respire aerobically
2 (this) produces more ATP 
3 ATP needed for , active transport / cell division /protein synthesis / DNA replication 
4. more ATP allows faster metabolic ,
processes / reactions

29
Q

Describe how the student could use the graph of rate of respiration vs rate of gas production to calculate the rate of respiration for each
type of sugar.

A

1 rate of respiration is proportional to
rate of gas production 
2 use a tangent 
3 calculate gradient (of each line) 
4 volume of gas (collected) divided by time 
5 compare the same , time / period (between sugars) 

30
Q

Explain why mitochondria produce CO2 when incubated with pyruvate, but do not produce CO2 when incubated with glucose.

A

glucose cannot enter mitochondria but pyruvate does.

CO2 produced during link reaction and Krebs, both in matrix, using pyruvate initially.

31
Q

Explain why lactate is not produced by mitochondria incubated with pyruvate

A

Lactate is product of anaerobic respiration which doesn’t occur in mitochondria

32
Q

Explain why, when cyanide is present, lactate is produced but not carbon dioxide.

A

Cyanide inhibits oxidative phosphorylation so aerobic stops

Anaerobic respiration occurs instead to oxidise NAD -> lactate pathway

This does not produce CO2. Glycolysis can continue where no decarboxylation occurs

OCR Biology A Level Module 5 Communication, homeostasis and energy (7 decks)

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