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Unit 10B - Biological Molecules and Metabolic Pathways
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- PEARSON (PEARSON)
10 B: Explore the effect of activity on respiration in humans and factors that can affect respiratory pathways
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10B: Explore the effect of activity on respiration in humansand factors that can affect respiratory pathways.
Respiration in Humans
To: Meltem Yilmaz
By: Jussara Rodrigues
Word count 5568
,B.P2
RESPIRATION
Introduction
Your cells need energy all the time and in order to use this energy, chemical
reactions must take place and in order to keep your cells alive chemical energy must
be produced from these reactions. The ATP, which I will be talking more about, is the
molecule that acts as a store of chemical energy and is released straight after when
the cells are in need. Muscle contraction is one of the processes that require this
type of energy within the cells.
Respiration is an immensely valuable process because it produces energy in the end
which is fundamental to keep cells alive. The ATP (adenosine triphosphate) is the
type of energy produced which can be stored and released when needed by the cells
and is extremely essential. ATP consists of adenine, ribose and three phosphate
groups, and the bonds between the two phosphate groups can be easily broken
down under the impact on an enzyme forming ADP (adenosine diphosphate) and an
inorganic phosphate. This break down which result in the formation of ADP happens
in all the stages on glycolysis, which is the first stage of respiration [1],[12].
Figure 1: Adenosine Triphosphate structure.
GLYCOLYSIS RESPIRATION
When carbohydrates are ingested, they are broken down by amylase in the mouth
into glucose, so that the body can absorb and use it for energy, through catabolic
process. While glucose, a 6-carbon compound, is being broken down it is also used
in the process of respiration inside the body by cells. Glycolysis is the first and key
process where energy is extracted from glucose for cellular metabolism. This
process takes place in the cytoplasm of a cell forming two molecules of ATP and 2
pyruvates, a 3-carbon compound, which are used to produce more ATP in Krebs
cycle and Link reaction. Glycolysis process is known as anaerobic as it does not
require oxygen in any of the steps. Before coming to the end of the pyruvates there
1
, are several intermediate molecules and reactions that occur, including specific
enzyme for each step to catalyse [1],[3].
The following reaction is the overall glycolysis:
C6H12O6 + 2 NAD+ + 2 ADP + 2 P → 2 pyruvate acid (CH3(C=O)COOH + 2 ATP + 2
NADH + 2 H+
Stages:
1. In this stage is where the glucose starts to break down, an ATP is hydrolysed
by releasing of phosphate group from ATP to glucose forming glucose-6-
phosphate. A glucose ring is phosphorylated, which the process is known as
phosphorylation. At this point one molecule of ATP has been consumed.
During the reaction hexokinase enzyme catalyses the phosphorylation
process.
2. Glucose-6-phosphate is converted into fructose-6-phosphate. This reaction
has a help of one enzyme called phosphoglucose isomerase This is an
isomerisation reaction, as it has the same molecular formula as glucose-6-
phosphate but different atomic arrangements.
3. Another ATP is hydrolysed, releasing one phosphate group that attaches to
carbon 1 and 6 of fructose-6-phosphate, and changing the structure to
fructose 1,6-biphophate. This reaction is under the help of
phosphofructokinase enzyme.
2
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