Page 38 - Cell biology PDG 2024

CHAPTER 4

BIOENERGETICS

Bioenergetics: it is a field in biochemistry and cell biology that
concerns with energy flow through living systems

It is also the study of the transformation of energy in living organisms
and the study of many cellular processes that lead to production and
utilization of energy in forms such as adenosine triphosphate (ATP)
molecules in order to make biological work

Life depends on energy transformations; living organisms survive by
exchanging energy between living tissues/ cells and the outside
environment

Autotrophs are organisms that can get energy from sunlight (through
photosynthesis) without needing to consume nutrients and break
them down, while heterotrophs must intake nutrients from food then
breaking down chemical bonds in nutrients during metabolic
processes such as glycolysis and the citric acid cycle to get energy

Living organisms can break chemical bonds as part of the exchange
and transformation of energy. This energy is available for work (such
as mechanical activity) or for other processes (such as chemical
synthesis and anabolic processes for growth)

Adenosine triphosphate (ATP) is the main "energy currency" for
organisms; the main purpose of metabolic and catabolic processes
are to synthesize ATP from available starting materials (from the
environment), and to break- down ATP (into adenosine diphosphate
(ADP) and inorganic phosphate) by utilizing it in biological processes

The ratio of ATP to ADP concentrations in a certain cell is known as
"energy charge". A cell can use this energy charge to relay
information about cellular needs; if there is more ATP than ADP
available, the cell can use ATP to do work, but if there is more ADP
than ATP available, the cell must synthesize ATP via oxidative
phosphorylation

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