These respiration notes cover everything in the AQA specification. They are detailed and include diagrams, helping you to learn what points to write in exam questions as well as helping things stick in your mind. Made using CGP guide, AQA textbook and class notes. A* achieved with these notes.
Respiration
Aerobic respiration requires oxygen and produces carbon dioxide, water and lots of ATP
Anaerobic respiration takes place in the absence of oxygen and produces lactate in animals or ethanol and carbon
dioxide in plants and fungi. Only a little ATP is produced
Glycolysis:
• Involves splitting one molecule of glucose into two smaller molecules of pyruvate (3C). This happens in the
cytoplasm of cells.
• It is the first stage of both aerobic and anaerobic respiration. It doesn’t need oxygen to take place so it is an
anaerobic process
There are two stages in Glycolysis- Phosphorylation and Oxidation:
Phosphorylation:
1. Glucose is phosphorylated using a phosphate from a molecule of ATP
This creates 1 molecule of glucose phosphate and 1 molecule of ADP
2. ATP is then used to add another phosphate, forming hexose biphosphate
3. Hexose biphosphate is then split into 2 molecules of triose phosphate
Oxidation:
1. Triose phosphate is oxidised as the hydrogen is removed from each of the two triose phosphate molecules,
forming 2 molecules of pyruvate
2. NAD (hydrogen-carrier molecule) collects the hydrogen ions, forming 2 reduced NAD
3. 4 ATP are produced, but 2 were used up in stage one, so there’s a net gain of 2 ATP
In aerobic respiration:
- The two molecules of reduced NAD go to oxidative phosphorylation
- The two pyruvate molecules are actively transported into the matrix of the mitochondria for the link reaction
In anaerobic respiration:
- The pyruvate is converted into ethanol in plants and yeast or lactate in animal cells and some bacteria using
reduced NAD
- The production of ethanol or lactate regenerates oxidised NAD. This means glycolysis can continue even when
there isn’t much oxygen, so a small amount of ATP can still be produced
The Link Reaction:
1. Pyruvate molecules are actively transported into the matrix of the mitochondria. It is decarboxylated- one
carbon atom is removed from pyruvate in the form of CO2
2. Pyruvate is oxidised to form acetate. It loses a carbon dioxide molecule and two hydrogens. The hydrogens are
accepted by NAD to form reduced NAD
3. Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A (acetyl CoA)
4. No ATP is produced in this reaction
The link reaction occurs twice for every glucose molecule so two molecules of each are produced/released
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Astudent100. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £4.20. You're not tied to anything after your purchase.
