Pp 69 – 73 & 217 - 237. 3.7 Cell respiration (Core) 3.7.1 Define cell respiration. 3.7.2 State...
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- Slide 1
- Pp 69 73 & 217 - 237
- Slide 2
- 3.7 Cell respiration (Core) 3.7.1 Define cell respiration.
3.7.2 State that, in cell respiration, glucose in the cytoplasm is
broken down by glycolysis into pyruvate, with a small yield of ATP.
3.7.3 Explain that, during anaerobic cell respiration, pyruvate can
be converted in the cytoplasm into lactate, or ethanol and carbon
dioxide, with no further yield of ATP. 3.7.4 Explain that, during
aerobic cell respiration, pyruvate can be broken down in the
mitochondrion into carbon dioxide and water with a large yield of
ATP.
- Slide 3
- 8.1 Cell respiration (AHL) 8.1.1 State that oxidation involves
the loss of electrons from an element, whereas reduction involves a
gain of electrons; and that oxidation frequently involves gaining
oxygen or losing hydrogen, whereas reduction frequently involves
losing oxygen or gaining hydrogen. 8.1.2 Outline the process of
glycolysis, including phosphorylation, lysis, oxidation and ATP
formation. 8.1.3 Draw and label a diagram showing the structure of
a mitochondrion as seen in electron micrographs. 8.1.4 Explain
aerobic respiration, including the link reaction, the Krebs cycle,
the role of NADH + H +, the electron transport chain and the role
of oxygen. 8.1.5 Explain oxidative phosphorylation in terms of
chemiosmosis. 8.1.6 Explain the relationship between the structure
of the mitochondrion and its function.
- Slide 4
- Define cell respiration Cell respiration is the controlled
release of energy from organic compounds in cells to form ATP
Glucose is the major substrate for respiration Adenosine
triphosphates (ATP) is the molecule which directly fuels the
majority of biological reactions.
- Slide 5
- Why cell respiration? Cells require a constant source of energy
to perform various tasks e.g. Movement Transport Division
- Slide 6
- Types of Respiration Occurs in the absence of Oxygen (ii)
Aerobic Respiration Occurs in presence of Oxygen Occurs in the
cells cytoplasmOccurs in the cells mitochondria Yields small amount
of ATP (2 molecules) per molecule of glucose Yields large amount of
ATP (38 molecules) per molecule of glucose Does not involve
fermentation Involves fermentation of pyruvate to lactate in
muscles/CO2 & ethanol in plant & yeast (i) Anaerobic
Respiration
- Slide 7
- Adenosine triphosphate (ATP): ATP is the chemical molecule
which directly fuels the majority of biological reactions About 10
25 ATP molecules are hydrolysed to ADP and inorganic phosphate (Pi)
daily ADP is reduced back to ATP using the free energy from the
oxidation of organic molecules
- Slide 8
- ATP Cycle
- Slide 9
- Glycolysis and Cell Respiration all types of cell respiration
starts with glycolysis glycolysis occurs in the cytoplasm of the
cell 1 glucose molecules is broken down into 2 pyruvate molecules
there is a net production of 2 ATP molecules glycolysis does not
require oxygen the fate of pyruvate depends on presence or absence
of oxygen
- Slide 10
- Anaerobic Cell Respiration anaerobic cell respiration occurs in
the absence of oxygen during glycolysis glucose is broken breakdown
in the cytoplasm leading to the production of pyruvate, production
of small amount of energy (2 ATP molecules per molecule of glucose)
in muscles, pyruvate is converted into lactic acid during lactic
acid fermentation anaerobic respiration occurs in animals during
intense muscular activity in yeast & plant cells, pyruvate is
converted into alcohol (ethanol) & CO 2 during alcoholic
fermentation no additional APT is produced during fermentation
- Slide 11
- Outline the process of aerobic respiration during glycolysis
glucose is partially oxidized in the cytoplasm small amount ATP
produced during glycolysis two pyruvate molecules are formed by
glycolysis pyruvate absorbed into mitochondrion pyruvate is broken
down in the mitochondrion in the presence of oxygen to produce
carbon dioxide & water large amount of energy in form of ATP is
produced per glucose molecule
- Slide 12
- Forms of oxidation and reduction cellular respiration involves
oxidation & reduction (redox) reactions oxidation involves the
loss of electrons from an element, gaining oxygen or losing
hydrogen by a substance reduction involves a gain of electrons,
losing oxygen or gaining hydrogen by a substance
- Slide 13
- Summary of oxidation and reduction
- Slide 14
- Animation: How the NAD + Works
- Slide 15
- Process of glycolysis glycolysis occurs in cytoplasm of the
cell & does not require oxygen hexose sugar (glucose) is
phosphorylated using ATP hexose biphosphate is split (lysis) into
two triose phosphates triose phosphates are oxidised by removal of
hydrogen by NAD + NAD + is concerted to NADH + H + there is net
gain of 2 ATP molecules (2 ATP are used & 4 ATP produced) 2
pyruvate molecules are produced per glucose molecule undergoing
glycolysis
- Slide 16
- Animation: How Glycolysis Works
- Slide 17
- Structure of a mitochondrion the electron micrograph on the
left shows the structure of a mitochondrion as seen under the
electron microscope draw a labelled diagram to show the structure
of a mitochondrion explain the relationship between the structure
of the mitochondrion and its function
- Slide 18
- electron micrograph interpretive drawing
- Slide 19
- Structural adaptation of mitochondrion to its function large
inner surface area of cristae for respiratory complexes such as
electron transport chains matrix contains DNA and ribosomes for
protein (enzyme) synthesis it also contains Krebs cycle enzymes
double membrane(s) isolates metabolic processes from the rest of
the cytoplasm small intermembrane space between inner and outer
membranes allows accumulation of protons for chemiosmosis
- Slide 20
- Aerobic respiration
- Slide 21
- Stages of aerobic respiration aerobic respiration includes the
following: glycolysis; basis of aerobic cell respiration, produces
ATP, reduced coenzymes & pyruvate link reaction; pyruvate is
transported into the matrix of the mitochondria Krebs Cycle;
decarboxylation of carbon fragments to yield ATP and reduced
coenzymes electron transport chain; reduced coenzymes are used to
generate more ATP
- Slide 22
- Key players in aerobic respiration Glucose: substrate, source
of fuel NAD + /FAD + : electron carriers Enzymes: mediate entire
process Mitochondria: site of aerobic respiration ATP: principal
end product Protons/Electrons: sources of potential energy Oxygen:
final electron acceptor
- Slide 23
- Link reaction Link reaction forms the link between glycolysis
& Krebs cycle pyruvate from glycolysis enters a mitochondrion
enzymes in the matrix of the mitochondria remove one carbon dioxide
and hydrogen from the pyruvate hydrogen is accepted by NAD + to
forms NADH + H + removal of hydrogen is oxidation removal of carbon
dioxide is decarboxylation the whole process in link reaction is
oxidative decarboxylation the product is an acetyl group which
reacts with coenzyme A (CoA) to form acetyl CoA which enters Krebs
cycle
- Slide 24
- Krebs Cycle During Krebs Cycle, also called citric acid cycle,
oxidative decarboxylation of the C2 Acetyl group (CH 3 CO) occurs
yielding ATP, reduced coenzymes & CO 2 is produced as a
by-product Acetyl CoA joins with the C4 acceptor group -
oxaloacetate CoA is released to transport more pyruvate into the
matrix A C6 fragment, citrate is formed C6 Citrate is oxidatively
decarboxylated A C5 group is formed The Carbon is given off as CO 2
NAD + is reduced to NADH + H + The C5 fragment is oxidised and
decarboxylated further to a C4 compound Again the carbon removed
forms CO 2 NAD + is further reduced to NADH + H + The final stage
in the cycle has the C4 acceptor regenerated There is a reduction
of NAD + to NADH + H + FAD (Coenzyme)is reduced to FADH 2 ADP is
reduced to ATP
- Slide 25
- Animation: How the Krebs Cycle Works
- Slide 26
- Oxidative phosphorylation in terms of chemiosmosis
- Slide 27
- Oxidative phosphorylation oxidative phosphorylation occurs
during the electron transport chain electrons are passed between
electron carriers this occurs in cristae of mitochondria releasing
energy the energy released is used to move protons against their
concentration gradient into the intermembrane space between the two
membranes finally, the protons join with oxygen to produce water
protons flow back to the matrix through the enzyme, ATP synthase
this movement of protons (hydrogen ions ) down the concentration
gradient is called chemiosmosis energy is released from
chemiosmosis which produces more ATP (i.e. combines ADP and
Pi)
- Slide 28
- Chemiosmosis There is high concentration of H + in the
intermembrane space & lower concentration in the matrix ATP
synthetase is an enzyme embedded in the cristae membrane H + create
an electrochemical gradient (chemical potential energy) The H +
passes through a channel in the enzyme driving the motor The motor
spins generating energy which bringing together ADP and Pi to
produce ATP
- Slide 29
- Animation: Electron Transport System and ATP Synthesis
- Slide 30
- Animation: Electron Transport System and Formation of ATP
- Slide 31
- Control of Cellular Respiration The important switch in the
control of respiration is the enzyme phosphofructokinase This
enzyme catalyzes step 3 of glycolysis Phosphofructokinase is
inhibited by ATP and stimulated by ADP or AMP. An example of
end-product inhibition in control of metabolic pathway It is also
inhibited by citric acid. This synchronizes the rates of glycolysis
and the Krebs Cycle
- Slide 32
- "Cell Respiration" - Cellular Respiration Song
- Slide 33
- Self Assessment Questions (SAQs) Define the term cell
respiration [2] Outline the process of anaerobic cell respiration
in yeast [6] Outline the process of aerobic cell respiration [6]
Outline the process of glycolysis [5] Draw labelled diagram of a
mitochondrion as seen in an electron micrograph [5] Explain the
relationship between the structure of the mitochondrion and its
function [5] Explain oxidative phosphorylation in terms of
chemiosmosis [9]