Unit 4: Respiration
Point 1: What is metabolism
• This refers to the chemical reactions taking place in a C_____.
• There are thousands of these occurring in each cell.
• To make them easier to understand they are arranged into M__________ pathways.
• Reactions releasing energy are C__________ reactions (e.g. respiration); those using energy are A__________ reactions (e.g. photosynthesis).
Point 2: How are respiration and photosynthesis linked?
1. Respiration is the R__________ of photosynthesis.
2. Respiration is an O__________ reaction whereas photosynthesis is a R___________ reaction, as shown here:
Point 1: What is cell respiration?
• G__________ is the main substrate for respiration, although L______ can also be used. It is oxidised in a series of small S_____ so that energy is released S______ and in an E_________ C________ way so that less energy is W_______.
Point 2: What is the overall equation for cell respiration?
C6H12O6 + 6O2 ( 6CO2 + 6H2O + 38ATP
• This is a simplification, there are around 30 steps to it, to understand it in detail we break it into 3 steps:
Before we go into the stages in detail, there are a few things to note:
• The different stages take place in different parts of the C_____. This allows the cell to C________ the stages more easily.
• The energy released by respiration is in the form of A____.
• The release of carbon dioxide takes place before oxygen is involved. It is therefore not T____ to say that respiration turns oxygen into carbon dioxide; it is more correct to say that respiration turns glucose into carbon dioxide, and oxygen into water.
• Stage 1 (glycolysis) is A__________ respiration, while stages 2 and 3 (Krebs cycle and The Electron Transfer Chain) are A_________ stages.
Point 3: Structure and function of mitochondria:
• Label the mitochondrion below:
• Much of respiration takes place in the mitochondria.
• The O_____ M_________ contains many protein channels, which let almost any small molecule through.
• The I______ M_________ is more normal and is impermeable to most materials. The inner membrane is highly folded to from C_______, giving a larger surface area.
• The electron microscope revealed blobs on the inner membrane which were originally called stalked particles. These have now been identified as the enzyme complex that synthesises ATP, and is more correctly called A____________ or A________.
• The space inside the inner membrane is called the M_________, and is where the Krebs cycle takes place (it also contains DNA, some genes are replicated and expressed here).
Point 4: Summary of the main stages:
1. Glycolysis: means ‘glucose S_______.’
• Glucose (6C) is split into P________ (2 x 3C molecules) with a net gain of __ATP molecules in the C_________ without using O_________.
• Hence, glycolysis is A___________ and is similar to F_______________.
(1a. The Link Reaction:
• P________ is oxidised to form A______ c______ A).
2. The Krebs Cycle:
• Electrons and CO2 are R_________ from acetyl coenzyme A.
3. The electron Transport Chain:
• ________ are transported down a series of electron C_______ transferring energy to make ____.
All of the stages are E________ controlled.
Point 1: The main reaction is:
1. Glucose enters cells from tissue fluid by F_________ D________...