2.8 + 8.2 - Cell Respiration Flashcards
Electron Tomography
is a technique for obtaining 3-d structures of sub-cellular structures using electron micrographs
Explain what Phosphorylation is
Phosphorylation is a reaction where a phosphate group (PO43-) is added to an organic molecule
The phosphorylated molecule is less stable and therefore reacts more easily in the metabolic pathway.
The phosphate group is usually transferred from ATP
Summarize glycolosis
in Summary:
Glycolysis occurs in cytoplasm
A hexose sugar (e.g. glucose) is phosphorylated using ATP
The hexose phosphate is then split into two triose phosphates
Oxidation occurs removing hydrogen
The hydrogen is used to reduce NAD to NADH
Four ATP are produced resulting in a net gain of two ATP
Two pyruvate molecules are produced at the end of glycolysis
explain oxidative decarboxylation - link reaction
In Summary:
pyruvate (from glycolysis) enters the mitochondrion matrix
enzymes remove one carbon dioxide and hydrogen from the pyruvate
hydrogen is accepted by NAD to form NADH
removal of hydrogen is oxidation
removal of carbon dioxide is decarboxylation
the link reaction is therefore oxidative decarboxylation
the product is an acetyl group which reacts with coenzyme A
acetyl CoA enters Krebs cycle
Krebs cycle - oxidative decarboxolation
In Summary:
acetyl CoA enters the Krebs cycle
acetyl group (2C) joins a 4C sugar to form a 6C sugar
oxidative decarboxylation of the 6C sugar to a 5C compound produces CO2
oxidative decarboxylation of the 5C compound to a 4C compound produces CO2
The process is oxidative as NAD and FAD are reduced by the addition of hydrogen
two CO2 are produced per molecule of pyruvate / cycle
along with three NADH + H+ and one FADH2 per molecule of pyruvate / cycle
one ATP is produced by substrate level phosphorylation (from ADP + Pi) per molecule of pyruvate / cycle
NADH and FADH2 provide electrons to the electron transport chain
oxidative phosphorylation (electron transport chain and chemiosmosis)
the electron transport chain is situated on the inner mitochondrial membrane
hydrogen is transferred to the electron transport chain by hydrogen carriers, i.e. NADH and FADH2
The hydrogen carriers release electrons which are transferred between carriers this releases energy …
…. which is used to pump H+ ions (from the matrix) across inner membrane
H+ ions to accumulate in the inter-membrane space creating a concentration gradient
H+ ions return to the matrix through ATP synthase
Down the electrochemical concentration gradient
This produces ATP by chemiosmosis
oxygen is the final electron acceptor for the electron transport chain
oxygen combines with electrons and H+ ions to produce water
chemiosmosis
the diffusion of ions across a semi-permeable membrane, through a carrier protien
in this case, the ions are hydrogen protons and the carrier protien in atp synthase
Nature of Science: Paradigm shift—the chemiosmotic theory led to a paradigm shift in the field of bioenergetics. (2.3
In 1961 Peter Mitchell proposed the chemiosmotic theory.
His ideas explained how synthesis is coupled to electron transport and proton movement.
His ideas were very different to previous explanations
It takes time for scientists working in a field to accept paradigm shifts, even when there is strong evidence
After many years the theory was accepted. Peter Mitchell received the Nobel Prize for Chemistry in 1978
label structure and function of mitochondria
Essential idea:
Cell respiration supplies energy for the functions of life.
define cell respiration
the controlled release of energy from organic compounds in cells
aerobic respiration
- occurs in th epresence of oxygen
- continues in the mitochondria
- a large yeild of atp is given
- water is a waste product recycled in the cell
- CO2 is excreted through gas exchange
anaerobic respiration
occurs in the absence of oxygen
reactions do not continue in the mitochondria
co2 and ethanol are produced in yeast (fermentation)
lactic acid is produced in humans and other animals
the yield of atp is very low
Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
Bread = water + flour and knead to make dough the bake it. Yeast is added to make the dough lighter and create air bubbles
Dough is kept warm for yeast to respire.
Yeast can respire aerobically or anaerobically, but oxygen in the dough is soon used up so the yeast is forced to respire anaerobically.
The carbon dioxide produced by anaerobic cell respiration cannot escape from the dough and forms bubbles causing the dough to swell and rise.
Ethanol is also produced by anaerobic cell respiration, but it evaporates during baking.
bioethanol
Bioethanol (ethanol produced by organisms) is a renewable energy source.
Most bioethanol is produced from sugar cane and maize, using yeast.
Starch and cellulose in the plant material are broken down by enzymes into sugars.
Fermenters are used to keep the yeast in optimum conditions
When yeast carry out anaerobic respiration the sugars in the plant material are converted to ethanol and carbon dioxide.
The ethanol produced by the yeasts is purified by distillation and water is removed to improve combustion.
