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Adrenaline (AQA A Level Biology): Revision Note

Exam code: 7402

Lára Marie McIvor

Written by: Lára Marie McIvor

Reviewed by: Naomi Holyoak

Updated on

The role of adrenaline

  • The hormone adrenaline can increase blood glucose concentration as follows:

    • it binds to receptors on the cell surface membranes of target cells

    • it activates enzymes that convert glycogen to glucose

The second messenger model of adrenaline action

  • The mechanism by which adrenaline activates enzymes is the same as that seen in glucagon

    1. Adrenaline binds to receptors on the membrane of liver cells

    2. Adenylate cyclase is activated

    3. Adenylate cyclase catalyses the conversion of ATP to the second messenger, cyclic AMP (cAMP)

    4. cAMP activates protein kinase A

    5. Protein kinase A initiates a cascade of reactions that results in the activation of enzymes that break down glycogen to glucose

Diagram showing the adrenaline pathway: adrenaline binds to a receptor, activating adenylyl cyclase, converting ATP to cAMP, triggering glycogen to glucose conversion.
Adrenaline activates enzymes that break down glycogen via the second messenger model of hormone action

Examiner Tips and Tricks

The specification covers the second messenger model in the context of glucagon and adrenaline, but you should be prepared to answer questions that require you to apply your understanding of this model to unfamiliar contexts.

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    Author
    Reviewer
    Lára Marie McIvor

    Author: Lára Marie McIvor

    Expertise: Biology, Psychology & Sociology Subject Lead

    Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

    Naomi Holyoak

    Reviewer: Naomi Holyoak

    Expertise: Biology Content Creator

    Naomi graduated from the University of Oxford with a degree in Biological Sciences. She has 8 years of classroom experience teaching Key Stage 3 up to A-Level biology, and is currently a tutor and A-Level examiner. Naomi especially enjoys creating resources that enable students to build a solid understanding of subject content, while also connecting their knowledge with biology’s exciting, real-world applications.