Week 6 cellular energetics

Question 1

Cell metabolism

Answer 1

Autotrophs -> obtain energy through photosynthesis
Heterotrophs -> by cellular respiration

Question 2

The breakdown of food molecules

Answer 2

During digestion, large food molecules are broken down (catabolism) into smaller molecules - monomers
ANABOLISM + CATABOLISM = METABOLISM
Catabolic pathways yield energy by oxidising organic fuels

Question 3

Cellular respiration

Answer 3

A step-wise process that breaks down (oxidation) sugars and other metabolites to CO2 and water
Convert the energy released from food into ATP molecules
Cellular respiration -> aerobic process (except glycolysis)

Question 4

ATP

Answer 4

Adenosine Triphosphate
Ribonucleoside triphosphate
Energy currency used to fuel chemical reactions in cells (also GTP) -> GTP has similar functions (guanine
replacing adenine)
Hydrolysis of high-energy phosphate bonds (γ-β link) release energy

Question 5

ATP – ADP cycle

Answer 5

ATP can be converted into ADP and recycled back (same for GTP/GDP)
The terminal phosphate bond of
ATP is broken down by hydrolysis
->ATP is converted into ADP and a phosphate, releasing energy
ATP -> ADP + phosphate +
energy
During cellular respiration, ADP is recycled back into ATP

Question 6

Oxidation of Organic Fuel Molecules

Answer 6

During cellular respiration, glucose and other metabolites are oxidized, and O2 is
reduced in a series of steps:
OXIDISATION -> a molecule (is
oxidised) loses electrons
REDUCTION -> a molecule (is
reduced) gains electrons
Step-wise manner process, electrons are transferred to electron carriers

Question 7

Electron carrying molecules

Answer 7

Electron carriers involved in cellular respiration:
->NAD+ (nicotinamide adenine dinucleotide)
->FAD (flavin adenine dinucleotide)
NAD+ and FAD (oxidized forms acting as electron acceptors) are reduced to NADH and FADH2
NAD+ + H+ + 2e- ⇄ NADH
FAD + 2H+ + 2e- ⇄ FADH2
Their reduced forms transfer protons and electrons to other molecules (the electron transport chain) where the energy is used to generate ATP

Question 8

Cellular respiration

Answer 8

Includes 4 phases;
1)Glycolysis
2)Pyruvate oxidation
3)Citric acid cycle
4)Oxidative phosphorylation

Answer 9

Question 10

Glycolysis

Answer 10

-To break down glucose (6-C atoms) into 2 pyruvates (3-C atoms)
-It generates 2 ATP + 2 NADH (NET result)
-Glycolysis occurs in the cytoplasm
Does not require oxygen
Consists of 10 different reactions (10 enzymes) in two major phases
-Energy investment phase
-Energy payoff phase
NADH transported into mitochondria, donating electrons to produces ATP