IB Biology - Curriculum Notes
2.8 Cell respiration - Cell respiration supplies energy for the functions of life.
∑ - Understandings:
∑ - Cell respiration is the controlled release of energy from organic compounds to produce ATP.
Organic compounds from the food we eat such as glucose contain stored energy within their covalent bonds.
All living organisms carry out cell respiration in order to convert stored energy into a form that can be used by the cell.
When organic molecules are broken down, the energy formed is eventually stored in a high energy molecule called ATP.
Cell respiration is the controlled release of energy from organic compounds in cells to produce ATP.
∑ - ATP from cell respiration is immediately available as a source of energy in the cell.
Energy for all types of cellular processes is immediately supplied by ATP
The main types of cellular activity include synthesizing large molecules (eg. DNA, RNA and protein), pumping ions across membranes by active transport, and moving things around the cell, such as vesicles and chromosomes. Muscle contractions also use ATP.
Energy is released by spitting ATP -> ADP + Pi
∑ - Anaerobic cell respiration gives a small yield of ATP from glucose.
Glucose (6C) is broken down into 2 pyruvates (3C) in the cytoplasm by the process of glycolysis.
There is a net gain of 2 ATP molecules.
Glycolysis does not require oxygen.
Anaerobic respiration (without oxygen) occurs in the cytoplasm.
During glycolysis, glucose is converted into pyruvate with a net gain of 2 ATP.
After glucose is converted to pyruvate, if no oxygen is available, pyruvate is further converted into lactate or ethanol depending on the organism.
When no oxygen is available, humans convert pyruvate into lactate (lactic acid) with no further gain of ATP.
No CO2 is produced because like pyruvate, lactate is also a 3 carbon molecule.
In yeast and plants, pyruvate is converted into ethanol (2C) and carbon dioxide with no further yield of ATP.
Ethanol and CO2 are excreted as waste products.
β - Applications and skills:
β - Application: Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
Read through “Yeast and its uses” on page 124-125 and answer the data-based questions on page 125.
β - Application: Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.
Discusses anaerobic respiration in humans.
∑ - Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose.
Aerobic respiration also begins with glycolysis which produces 2 pyruvate molecules per glucose.
Aerobic respiration occurs in the mitochondria.
Aerobic respiration is much more efficient than anaerobic respiration as the glucose molecule is fully oxidized.
The products created in the redox reactions of the Kreb’s cycle, plus oxygen (terminal electron acceptor) will produce large quantities of ATP through oxidative phosphorylation (phosphate added to ADP to form ATP) in the ETC, with water being released.
Overall in aerobic respiration glucose + oxygen will produce carbon dioxide + water with a large yield of ATP
About 32-34 molecules of ATP are produced by aerobic respiration, while in anaerobic respiration, only 2 ATP molecules are produced
***Do data based questions on page 128***
B Skill: Analysis of results from experiments involving measurement of respiration rates in germinating seeds or invertebrates using a respirometer.
Lab Practical – Using a respirometer to measure the rate of respiration in germinating peas - Can use an online simulation for online learning http://www.phschool.com/science/biology_place/labbench/lab5/intro.html