Marked 25/25 mark essay for A level Biology about the uses and importance of ATP in organisms. 4 detailed paragraphs and 815 words including an essay plan.
Topics included: ATP, active transport, respiration, muscle contraction
The uses and importance of ATP in organisms
Essay Plan:
Topic: AO1: (uses) AO2: (importance)
ATP ▪ Hydrolysis of ATP e.g., in ▪ Provides energy when
protein synthesis hydrolysed
▪ Resynthesis of ATP ▪ Phosphorylation with
phosphate group e.g.,
makes molecules more
reactive
Active Transport ▪ Against concentration ▪ ATP drives this process so
gradient so needs energy without it active transport
from ATP won’t occur
▪ Phosphate from ATP causes ▪ Ensures a good balance of
change in carrier protein substances
shape
Respiration ▪ Phosphorylation of glucose ▪ No respiration = insufficient
▪ Production of 38 ATP oxygen supply = muscle
fatigue
▪ Lactic acid builds up
Muscle Contraction ▪ ATP provides energy for ▪ No ATP = cross bridges
myosin heads to bend don’t break = constant
▪ Breaks myosin-actin cross muscle contraction
bridge = contraction
ATP (adenosine triphosphate) is made by mitochondria during aerobic respiration and is used
by eukaryotic cells and is vital in organisms as it transports and provides the energy needed for
all cellular metabolic processes and without it, organisms would not be able to survive. ATP is
formed from a molecule of ribose sugar and three phosphate groups. Protein synthesis
requires energy from the hydrolysis of ATP. This is achieved by ATP hydrolase or ATPase which
breaks the bond between the second and third phosphate groups leading to the formation of
ADP (adenosine diphosphate) and an inorganic phosphate group. These bonds have energy
stores between them so when they are broken, energy is released. The inorganic phosphate
group often binds to other molecules to make then more reactive, so they can take part in
another reaction. It is also important that ATP is resynthesized by joining ADP molecules with
inorganic phosphate groups via condensation reactions facilitated by the enzyme ATP
synthase. These reactions also require energy which is provided by carbohydrate or lipid
molecules being hydrolysed during respiration.
One metabolic process which requires energy from the hydrolysis of ATP is active transport.
Active transport is the movement of substances against the concentration gradient. Unlike
other modes of transport, active transport requires external energy because substances are
moving from a region of lower concentration to a higher concentration. This external energy is
provided by the hydrolysis of ATP. A key example of active transport in organisms is the
transport of potassium and sodium ions via the sodium potassium pump. There is an
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