Transcript 3 ATP and energy release

Higher Human Biology
Unit 1: Cell Function and
Inheritance
Chapter 4: ATP and
energy release
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Lesson Aims
• To compare aerobic and anaerobic
respiration
• To learn about structure and function of
ATP
• To learn about the three stages of
respiration
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Previous Knowledge…
• What is the definition of Respiration?
• Difference between aerobic respiration and
anaerobic respiration?
• How can you show that a living thing gives off
energy when it is respiring?
• How can you prove that an organism releases
CO2 during respiration?
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Previous Knowledge…
Glucose + O2
Glucose
Glucose
CO2 + Water + energy
Lactic acid + energy
Ethanol + CO2 + energy
aerobic respiration
anaerobic respiration
(animals)
anaerobic respiration
(plants)
aerobic respiration
anaerobic respiration (plants)
anaerobic respiration (animals)
Remember that respiration occurs in EVERY
LIVING THING
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Metabolism
• Metabolism - all chemical reactions that
occur in cells
• Catabolism – produces energy when bonds
between atoms in our food are broken
• Anabolism – requires energy to make new
bonds building up molecules
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Aerobic Respiration
• Organisms break down organic materials
through the process of aerobic cellular
respiration.
• The goal of this process is to break down
organic material and harness the released
energy in the form of ATP, the universal
currency of biological energy.
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Anaerobic Respiration
• A few organisms can live without oxygen
(anaerobically). These organisms are
capable of metabolizing organic material,
but their ATP yield is much lower than that
found in aerobic respiration.
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ATP
• ATP = Adenosine
triphosphate
• ATP is a molecule that
transports energy made
during respiration and
releases it for cellular
processes (e.g. unzipping
DNA, making enzymes…)
adenosine
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Pi
Pi
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Pi
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GEEKY SCIENCE JOKE
• Man goes into a bar,
• Barman says “What can I get you?”
• Man says “I’ll have a pint of Adenosine
triphosphate”
• Barman says “Ahhhh that will be ATP”
• (80p.... Get it!!!! boom-chh)
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Experiment the contraction of
muscle fibre by ATP
A:ATP
B:Glucose
C:Water
MUSCLE FIBRE
In this experiment, the substance under investigation is adenosine
triphosphate (ATP). This substance occurs in all living cells. The tissue
used in this experiment is muscle. The contraction of the muscle is
evidence that energy is being used. Ringer's solution is a solution of salts in
water at about the same osmotic concentration as tissue fluid.
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Analysing the results.
• When each of the slides has been exposed to its appropriate
solution for at least five minutes, measure the lengths of the
muscle filaments again, record this in your table and work out
the amount of contraction and percentage contraction.
A (ATP)
B (Water)
C (Glucose)
1st length
2nd length
Decrease
% contraction
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Experiment Discussion
1. Which of the three solutions caused the greatest percentage
contraction?
2. Glucose is generally considered to be the main source of
energy for reactions such as muscle contraction (e.g. athletes
may eat glucose tablets before strenuous effort). Discuss
whether your results support this view.
3. The animal from which the muscle was obtained has probably
been dead for many days. Does the fact that muscle fibres will
still contract mean that the muscle is still alive?
4. Discuss whether the results of the experiment entitle you to
say that ATP causes muscle contraction in living organisms.
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ATP releases energy by
rd
breaking the 3 chemical bond:
adenosine
Pi
Pi
Energy
stored in
this bond
Pi
Pi
adenosine
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Pi
Pi
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Energy
released
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This leaves us with an energy-less
molecule called ADP (adenosine
diphosphate) and a spare phosphate
Pi
adenosine
Pi
Pi
• These molecules are recycled as the
chemical energy released during respiration
remakes the third bond to make… ATP
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The ATP EQUATION
• The process is therefore a reversible
reaction:
ATP
Energy released
ADP + Pi
Energy required
When ATP is synthesised (made) we
refer to it as phosphorylation (adding a
phosphate).
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Energy Transfer
Chemical
energy from
Respiration
ADP + Pi
ATP
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Cellular
reactions
e.g.
Protein synthesis
Muscle contraction
Active transport
Nerve impulses
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Respiration
3 stages:
• Glycolysis
• Kreb’s cycle
• Cytochrome system
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OILRIG
• In a biochemical pathway, OXIDATION
occurs when hydrogen is removed from a
substrate. This releases energy.
• REDUCTION adds hydrogen and costs
energy.
• Respiration is an oxidation reaction…
• Like all biochemical pathways, respiration
is controlled by enzymes
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ATP TOTAL
GLUCOSE
C6H12O6
GLYCOLYSIS
= 2
CYTOCHROME SYSTEM = 36
TOTAL
2 ATP
= 38
PYRUVIC
ACID
CYTOPLASM
GLYCOLYSIS
OCCURS HERE
MITOCHONDRION
ACETYLCoA
H2O
AEROBIC RESPIRATION
OCCURS HERE
O2
KREBS
CYCLE
HYDROGEN
CYTOCHROME
SYSTEM
36 ATP
CO2
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Glycolysis -1st stage
• Glycolysis is a part of both aerobic respiration and
anaerobic respiration – this stage doesn’t require oxygen.
• Takes place in the cell cytoplasm
• Here, a molecule of glucose (6C) is split into two
molecules of pyruvic acid (3C).
• Net gain of 2 ATP
• Hydrogen released is transferred to Cytochrome system
by NAD
• If no oxygen present, pyruvic acid converted to lactic
acid
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Glycolysis
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Mitochondria Structure
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Mitochondria
• Mitochondria are found in the cytoplasm of cells
• The fluid-filled interior of the mitochondrion is
called the matrix
• The cristae of the mitochondria is located on the
inner membrane
• The folded inner membrane of the mitochondria
provides a large surface area
• More active cells (e.g. muscle, sperm & nerve
cells) have many cristae in their many
mitochondria as they require more ATP (energy)
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Kreb’s Cycle – Stage 2.
• Aerobic _ Only proceeds when oxygen is present.
• Takes place in matrix of mitchondria
• Also called TCA (Tricarboxylic Acid Cycle ) or Citric acid
cycle
• Pyruvic acid (3C) diffuses into matrix and is broken
down into Acetyl CoA (2C)
• Acetyl CoA binds with 4C molecule to give citric acid
• Citric acid broken down into 4C molecule by series of
enzyme-controlled reactions
• Produces CO2
• Hydrogen released is transferred to Cytochrome system
by NAD
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Kreb’s Cycle
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• Throughout Glycolysis and the Kreb’s
Cycle, the substrate is continually altered
by the removal of carbon (in the form of
CO2) and the removal of Hydrogen.
• What happens to the CO2?
• What happens to the Hydrogen?
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Cytochrome System -3rd stage
Ever wondered what the heck happened to all
that NAD  NADH2…?
• Also called electron transfer chain
• Hydrogen passed along chain
• The NAD carries the H to the Cristae of the
Mitochondria.
• The energy from the H electrons is the energy
needed to synthesise ATP from ADP and Pi
(remember? The 3rd bond etc.?)
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Cytochrome System –Con’t
• 36 ATP molecules are made from each
molecule of glucose in the cytochrome
system
• Once the Hydrogen has been passed
through the system and lost the electrons,
it joins with OXYGEN as its finale.
• The oxygen is therefore said to be the final
hydrogen acceptor. This makes WATER!
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Cytochrome System – hydrogen
chain.
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The Big
Picture..
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Summary
• One molecule of glucose gives a total yield
of 38 ATP
– 2 from glycolysis
– 36 from cytochrome system
• The Citric acid cycle turns twice for each
molecule of glucose as there are 2 x PA
(see page 7 of workbook)
• Glucose + O2  CO2 + H2O + 38 ATP
• Respiration is carefully controlled by
various ENZYMES!
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Anaerobic Respiration
• If Oxygen is not present, then the
biochemical process we have studied –
aerobic respiration – cannot happen.
• Glucose (6C)
2 ATP
Pyruvic Acid (3C)
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Lactic Acid (3C)
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Anaerobic Respiration
• If Oxygen is not present, then the
biochemical process we have studied
cannot happen.
• Glucose (6C)
2 ATP
Pyruvic Acid (3C)
Lactic Acid (3C)
O2
available
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• “Oxygen debt” and “reversible”
• Only the 2 ATP from Glycolysis is made
• Therefore the net gain of anaerobic
respiration is 2 ATP
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Anaerobic Respiration (Plants)
• In plants and yeast anaerobic respiration
takes a different and irreversible pathway.
• Glucose (6C)
2 ATP
Pyruvic Acid (3C)
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CO2 + Ethanol
How many
carbons?
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Justify answer.
TASK!!! Essay Question
•
An essay question is usually 10 marks in
the exam you would have about 15
minutes to complete each essay.
• Give an account of Respiration under the
following headings:
(i) Glycolysis
(3)
(ii) Kreb’s Cycle
(4)
(iii) Cytochrome system
(3)
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(i) Glycolysis
Max 3
• 6C Glucose is broken down into 2 molecules of
3C Pyruvic Acid
• Hydrogen is released and picked up by NAD to
become NADH2
• NADH2 goes to Cytochrome System (or cristae
of mitochondria)
• Glycolysis makes 4 ATP but costs 2 ATP
resulting in a net gain of 2 ATP
• Glycolysis takes place in the cytoplasm of the
cell
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(ii) Kreb’s Cycle
Max 4
• 3C PA is converted in 2C Acetyl CoA
• Acetyl CoA enters the matrix of the mitochondria
• Acetyl CoA joins with 4C intermediate compound to form
6C Citric Acid
• Citric Acid is changed into a 5C compound which is then
changed into a 4C compound
• Each time a Carbon is removed, it is released as CO2
and eventually breathed out
• Hydrogen is also released (oxidation) which combines
with NAD to make NADH2 (reduction)
• NADH2 goes to Cytochrome System
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(iii) Cytochrome System Max 3
• Cytochrome System is located on the cristae of the
mitochondrion
• NADH2 is reduced/released Hydrogen
• As Hydrogen is passed along Cytochrome System, it
loses electrons which released energy
• This energy is needed to regenerate ATP by
phosphorylation/from ADP and Pi
• The Hydrogen then combines with Oxygen to form
metabolic water
• The Cytochrome system makes 36 ATP
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