Steps of cell respiration
Table of Contents
As mentioned in the previous tutorial on ATP, the process of respiration is split into 3 distinct areas that occur at different parts of the cell. Respiration involves the oxidation of foodstuff (i.e. glucose) in order to create ATP.
Respiration can occur with or without oxygen, aerobic and anaerobic respiration respectively.
Glycolysis occurs in the cytoplasm of a cell where a 6 carbon glucose molecule (the broken down food that you ate earlier) is broken down by enzymes into a 3 carbon pyruvic acid.
The execution of this process requires 2 ATP and produces a net gain of 2 ATP.
The enzymes involved remove hydrogen from the glucose (oxidation) where they take these hydrogen atoms to the cytochrome system, explained soon.
In anaerobic respiration, this is where the process ends, glucose is split into 2 molecules of pyruvic acid. When oxygen is present, pyruvic is broken down into other carbon compounds in the Kreb’s Cycle. When it is not present, the pyruvic acid is broken down into lactic acid (or carbon dioxide and ethanol).
When oxygen is present, respiration can harness more ATP from a single unit of glucose. The pyruvic acid from the glycolysis stage diffuses into a cell organelle called a mitochondrion (pl. mitochondria). These mitochondria are sausage-shaped structures that host a large surface area for respiration to occur on.
The pyruvic acid is then subject to more enzymes that break it down into a 2 carbon compound, as seen below. The diagram illustrates the Kreb’s cycle, consisting of three main actions
The cytochrome system, also known as the hydrogen carrier system (or the electron transport system) are where the reduced hydrogen carriers transport hydrogen atoms from the glycolysis and Kreb’s cycle stages. The cytochrome system is found in the many cristae of mitochondria, which are tiny stalked particles found on its outer layer.
The system contains many ‘hydrogen acceptors’ which hydrogen can be added to. By following the path of a hydrogen atom, we can see how the cytochrome system works:
The diagram illustrates this flow of hydrogen within the cytochrome system and how energy is made available by the flow of these atoms. The green circles illustrate where energy is made available via oxidation.
Overall there is a gain of 38 ATP from one molecule of glucose in aerobic respiration. The food that we eat provides glucose required in respiration. In plants, energy is also acquired via respiration, but the mechanism of delivering glucose to the respiration process is a little different.
Photosynthesis is the process that plants undertake to create organic materials from carbon dioxide and water, with the help of sunlight- all of which are investigated in the next tutorial.
Animals adapt to their environment in aspects of anatomy, physiology, and behavior. This tutorial will help you understa..
Plants need to regulate water in order to stay upright and structurally stable. Find out the different evolutionary adap..
The water cycle (also referred to as the hydrological cycle) is a system of continuous transfer of water from the air, s..
Adaptation, in biology and ecology, refers to the process or trait through which organisms or the populations in a habit..
Plantlife can be studied at a variety of levels, from the molecular, genetic and biochemical level through organelles, c..
This tutorial digs into the past to investigate the origins of life. The section is split into geological periods in the..