AQA · A-Level · Biology
Course version: 7402 · Version from Sept 2016
Students should be able to relate the structure of proteins to properties…
Full specification wording
General properties of proteins: Students should be able to relate the structure of proteins to properties of proteins named throughout the specification.
This statement is synoptic: whenever the specification names a protein, you should be able to trace its property back to its structure.
Checked against the AQA 7402 specification (opens in a new tab) on .
- Point 9 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
This statement is synoptic: whenever the specification names a protein, you should be able to trace its property back to its structure. Haemoglobin has a quaternary structure of four polypeptides, each with a haem group, allowing the shape change behind cooperative binding and the S-shaped dissociation curve. Antibodies also have a quaternary structure, with variable regions forming specific antigen-binding sites complementary to a single antigen. Enzymes depend on tertiary structure, because the active site must stay complementary to the substrate; denaturation breaks hydrogen and ionic bonds so the site no longer fits. Channel proteins are specific because their tertiary structure admits only particular ions.
What earns the marks
- Naming the level of structure responsible for a stated property, such as quaternary structure in haemoglobin.
- Linking the tertiary structure of an active site or binding site to specificity and complementary shape.
- Explaining a loss of function through broken hydrogen and ionic bonds changing the tertiary structure.
- Relating an antibody's specificity to the tertiary structure of its variable region.
- Making the link explicit between the structural feature and the property, rather than stating them separately.
Common mistakes and how to put them right
Describing a protein's structure and its property in separate sentences without linking them.
Attributing enzyme specificity to primary structure directly, missing the tertiary structure step.
Saying denaturation breaks peptide bonds rather than hydrogen and ionic bonds.
Using shape rather than tertiary structure when explaining how a binding site works.
Exam tips
- Build a table of every named protein in the specification with its level of structure and the property that follows from it.
- In extended answers, integrate the topics rather than listing them; the highest bands reward linked, clearly explained points across several areas.
- Use complementary, tertiary structure and binding site as your standard vocabulary for any protein-function explanation.
Try the lesson
The start of the General properties of proteins: Students should be able to relate the structure of proteins to properties of proteins named throughout the specification. lesson, made from checked teaching notes for this specification point.
Have a go first
Collagen is a fibrous protein found in connective tissue. Which structural feature of collagen best explains its high tensile strength?
Listen
This statement is synoptic: whenever the specification names a protein, you should be able to trace its property back to its structure. Haemoglobin has a quaternary structure of four polypeptides, each with a haem group, allowing the shape change behind cooperative binding and the S-shaped dissociation curve. Antibodies also have a quaternary structure, with variable regions forming specific antigen-binding sites complementary to a single antigen. Enzymes depend on tertiary structure, because the active site must stay complementary to the substrate; denaturation breaks hydrogen and ionic bonds so the site no longer fits. Channel proteins are specific because their tertiary structure admits only particular ions. A strong answer earns marks for these points. naming the level of structure responsible for a stated property, such as quaternary structure in haemoglobin. linking the tertiary structure of an active site or binding site to specificity and complementary shape. explaining a loss of function through broken hydrogen and ionic bonds changing the tertiary structure. relating an antibody's specificity to the tertiary structure of its variable region. Exam tip: Build a table of every named protein in the specification with its level of structure and the property that follows from it.
Key words
Say what each word means before you turn the card.
structure to property reasoning
Try answering aloud or in your head before turning the card.
haemoglobin and antibodies
Try answering aloud or in your head before turning the card.
active sites and binding sites
Try answering aloud or in your head before turning the card.
denaturation
Try answering aloud or in your head before turning the card.
See every definition
- structure to property reasoning
- Making the link explicit between a structural feature of a protein and the property that follows from it, rather than stating them separately.
- haemoglobin and antibodies
- Proteins with a quaternary structure of four polypeptides, each with a haem group in haemoglobin, or with variable regions forming specific antigen-binding sites in antibodies.
- active sites and binding sites
- Sites whose tertiary structure must stay complementary to the substrate, or whose variable regions form specific antigen-binding sites complementary to a single antigen.
- denaturation
- Breaking of hydrogen and ionic bonds so the tertiary structure changes and the site no longer fits.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of General properties of proteins: Students should be able to relate the structure of proteins to properties of proteins named throughout the specification.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge