Topic 17: Cellular Respiration

Question 1

Name some elements essential to life

Answer 1

Hydrogen, carbon, nitrogen, oxygen, sodium, magnesium, phosphorus, sulfur, potassium, calcium, iron

Question 2

Describe the energy of electrons as going further away from the nucleus and state which part of electrons participate in biological process

Answer 2

The further from the nucleus, the high the electron’s energy.
Valence shell electrons (outer most) participate in biological process.

Question 3

Differentiate different compounds forming based on electronegativity

Answer 3

• Ionic compounds: large EN difference (one take electrons from the other)
• Covalent (molecular) compounds: small EN difference (share electrons)

Question 4

Describe 2 types of covalent bonds

Answer 4

• Polar covalent bonds: small EN differece –> unequal sharing of electrons
• Non-polar covalent bonds: equal EN –> equal sharing of electrons

Question 5

Explain oxidation-reduction process and give an example related to biological process in body

Answer 5

Oxidation-reduction reaction happens when one molecule is oxidised, or lose H+/electrons, and another is reduced, or receive H+/electrons.
Breakdown of glucose to CO2 is a oxidation-reduction reaction in which the Carbon gets oxidised and Oxygen gets reduced.

Question 6

Differentiate catabolism and anabolism reactions with examples

Answer 6

• Anabolic reaction is formation of larger molecules as in glucose coming together to produce glycogen or amino acids chain up to create peptides.
• Catabolic reaction is breakdown of molecule into smaller components as in proteins being broken down into peptides.

Question 7

Describe the role of ATP as an exchange coin between between catabolic and anabolic processes

Answer 7

Catabolic reactions produce ATP which acts as energy currency used to build up other substances in anabolic reactions.

Question 8

Identify and describe the two main coenzymes present in ATP synthesis

Answer 8

• Nicotinamide adenine dinucleotide:
  + NADH (reduced form): carries electrons and a good electrons donor
  + NAD+ (oxidised form): NOT carries electrons and a good electrons receiver
• Flavin adenine dinucleotide:
  + FADH2 (reduced form): carries electrons and a good electrons donor
  + FAD (oxidised form): NOT carries electrons and a good electrons receiver

Question 9

Describe glucose catabolism through the processes of glycolysis, the intermediate reaction, the Krebs Cycle and oxidative phosphorylation.

Answer 9

Glucose enters the body and go through a series of steps to be able to be used as ATP.
- Glycolysis: an anaerobic process in cytosol
+ glucose is processed to make 2 pyruvate and 2 ATP
+ some energy is released and captured as electrons by NAD+ to make NADH

• Intermediate action: aerobic process in mitochondria matrix
  + pyruvate get split to make 2-carbon sugar + CoA to make 2 acetyl CoA
  + the remaining carbon is turned into CO2
  + some energy is released and captured as electrons by NAD+ to make NADH
• Krebs cycle: aerobic process in mitochondria matrix
  + produces 2 CO2, 4 coenzymes (NADH and FADH2), and 1 ATP
• Oxidative phospholyration: main mechanism in ATP synthesis , aerobic process in mitochondria
  + Electron transport chain:
  ~ Protein complexes embedded in the inner mitochondrial membrane get reduced by receiving electrons followed with H+ ions from NADH and FADH2.
  ~ The process of electron donation creates energy which is used to pump H+ ions into the intermembrane space.
  ~ Some electrons eventually fall to O2 (H+ follow) to create water
  + Chemiosmosis:
  ~ H+ ions concentrate in the intermembrane space creating a concentration gradient
  ~ H+ ions flow down the gradient via ATP synthase, leading to high potential energy used to combine ADP + Pi to create ATP

The final amount of ATP can go up to 38.