What Is Aerobic Respiration Synthesis And Aerobic Respiration

Deoxyribose nucleic acid (DNA) contains a double helix structure that are antiparallel and weak hydrogen bonds, which can be broken. It contains complementary based pairing nucleotides. Adenine is paired with Thymine and Guanine is paired with Cytosine.1 Protein synthesis is divided into two main processes; transcription and translation.

Transcription occurs in the nucleus and it is the process whereby the DNA is used as a template to form a complementary messenger ribonucleic acid (mRNA) molecule. Unlike DNA, mRNA does not contain the nucleotide base Thymine. It is however, replaced by Uracil. Free nucleotides from the cytoplasm migrate into the nucleus, and following base pair rules, bind to the exposed nucleotides on the 3’ to 5’ strand

Cellular respiration can be both anaerobic (no oxygen) and aerobic (presence of oxygen), depending on the oxygen present. Anaerobic respiration produces 2 ATP molecules and lactic acid as a by product, which is poisonous to the cells. In contrast, aerobic respiration produces a total of 36 ATP molecules.1 Aerobic respiration can be represented by the following equation: C6H12O6 + 6O2 6CO2 + 6H2O [ + ATP ]

The synthesis of ATP begins in the cytoplasm of cells in an anaerobic process known as glycolysis. If oxygen is present, the synthesis of ATP continues in the mitochondria through processes known as the Krebs cycle and the electron transport chain (ETC).1

Glycolysis involves the break down of glucose into 2 pyruvic acids (3 carbon molecules) and yields only 2 ATP molecules. This process also produces 2 molecules of NADH.2

The latter stages of cellular respiration continue in the mitochondria. The Krebs cycle occurs in the mitochondria and it produces large amounts of NADH and FADH2 molecules. These molecules are then used in the ETC where the hydrogen ions are removed from the molecule and transferred out of the inner mitochondria membrane into the outer membrane.1 This creates a proton gradient and through diffusion, the hydrogen ions diffuse back into the inner membrane, which drives the enzyme, ATP synthesise to produce ATP

The cell membrane consists of a phospholipid bi-layer which allows receptors, G – Proteins, and enzymes to move freely in the membrane.1 G – Proteins consist of several subunits (alpha, beta, and gamma). GDP is bounded to the alpha subunit in the resting state.1

2. Neurotransmitter binds to the receptor on the cell membrane, which causes a change in the shape of the receptor.1

3. This change allows the receptor to bind to the G – Protein molecule, if it collides with the molecule.

4. The G – Protein then changes it affinity for a GTP molecule rather than a GDP molecule. The GTP molecule enables the alpha subunit to detach from the protein, or changes the alpha unit, resulting in an interaction with the enzymes or channels.1

5. As a result of the GTP, the enzyme becomes active and may catalyse reactions.

6. The neurotransmitter then leaves the receptor, enabling it to return back to its original shape.

7. GTP is then hydrolysed to GDP, which prevents further reactions from occur.1 In other words, the enzyme is no longer effective.

8. The G – Protein subunits recombines (the alpha attaches back to the beta and gamma