Date post: | 01-Apr-2015 |
Category: |
Documents |
Upload: | zayne-hessey |
View: | 221 times |
Download: | 0 times |
Cellular Respiration
Pp 78-83
3.7 Cell respiration 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.
Syllabus Definition
Cell respiration is the controlled release of energy from organic compounds in cells to form ATP
Metabolize/breakdown/ “slow oxidation”
Oxidation
Oxidation involves the loss of electrons from an element, whereas reduction involves the gain of electrons and that oxidation frequently involves gaining oxygen or losing hydrogen, whereas reduction frequently involves losing oxygen or gaining hydrogen.
“Biology” definition of “oxidation”
cell respiration
Takes place in cytoplasm (glycolysis) and the mitochondria (Krebbs and Electron Tranport Chain)
Glucose is the major substrate for respiration
Adenosine triphosphates (ATP) is the product and the molecule which directly fuels the majority of biological reactions.
Why cell respiration?Cells require a constant source of energy (renewed daily) to perform various tasks e.g.
Metabolism, Synthesis, Active Transport, Locomotion, Cell Structure, Cell Communication, DNA/RNA Synthesis, tRNA Protein Synthesis
Types of Respiration
Occurs in the absence of Oxygen
(ii) Aerobic Respiration
Occurs in presence of Oxygen
Occurs in the cells’ cytoplasm Occurs 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 fermentationInvolves fermentation of pyruvate to lactate in muscles/CO2 & ethanol in plant & yeast
(i) Anaerobic Respiration
Comparison between Aerobic & Anaerobic Respiration -Animals
Adenosine triphosphate (ATP):ATP is the chemical
molecule which directly fuels the majority of biological reactions
About 1025 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
ATP Cycle
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) & CO2
during alcoholic fermentation
no additional APT is produced during fermentation
“Three stages” of aerobic respirationStage 1: 2 ATP
Glycolysis (energy investment) 4 ATP is made, 2 is used –
Stage 2 (and 3): 38 ATP Krebs Cycle (oxidation of pyruvate)
Lots of energy carriers - Generation of CO2
Oxidative Phosphorylation Generation of most ATP
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
WhereCell’s
cytoplasmWhy
To break glucose down into pyruvate, which feeds into the Krebs Cycle
To regenerate NAD, an electron carrier
Stage 1: Glycolysis
Krebs Cycle
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
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
Aerobic respiration
Three stages of respiration
Summary