Topic 1A- Biological Molecules (Proteins) Flashcards
What are amino acids sometimes called?
Why does this mean that they can also be called and why?
How many different amino acids are there found in nature?
What are the building blocks of proteins called?
What is a polymer?
What are the individual units called?
What are/describe the two groups in the structure of an amino acid?
What does the R represent in the structure of an amino acid?
What is each R group made up?
What two things does this result in each amino acid having?
Peptides
Polypeptides because they are made up from many peptides joined together
There are 20 different types of amino acids
Amino acids
A molecule that is made up of smaller repeating units
Monomers
- An amine group (NH2)
- A carboxyl group (-COOH), which is acidic
The R represents different atoms attached to the amino acid
Each R group is made up of different atoms
Slightly different chemical/physical properties.
What does the joining of two amino acids release?
What is this reaction called?
What is the bond made when two amino acids join together called?
What happens when the amino acids are split apart again and give an example?
What is this reaction called?
What is the test called that is used to test for the presence of proteins?
What is the colour change?
What are the different steps for the biuret test for proteins?
Why does this test work (full explanation)?
Releases a molecule of water
A condensation reaction
Peptide bond
Water is used (ie water is added), eg in digestion
A hydrolysis reaction
Biuret test for proteins
The mixture changes from blue to purple
- Biuret solution is a mixture of Sodium Hydroxide and Copper Sulphate
- This is a clear blue solution
- In the presence of protein, the mixture changes from blue to purple
Because the copper ions form bonds with the peptide bonds in the proteins, and this leads to a colour change.
What is the primary structure of a protein?
What aren’t and are the protein chains?
What is the secondary structure of a protein (full definition)?
What are the secondary structures held together by?
How do these form by?
Describe the alpha helix chains?
What does the “alpha” mean?
Describe the beta-pleated sheets?
What is an anti-parallel sheet?
Describes the order of the amino acids joined together to make the protein
The protein chains are not randomly arranged, and are also organised into a secondary structure
Regions where the chains are organised into regular structures known as alpha helices and beta pleated sheets (both are the secondary structures of proteins)
Hydrogen bonds
These form between one of the lone pairs on an oxygen atom and the hydrogen attached to a nitrogen atom
Where the protein chain is coiled loosely like a spring
That if you look down the length of the spring, the coiling is happening in a clockwise direction as it goes away from you
Where the chains are folded to lie alongside each other
Where the next-door chains are heading in opposite directions.
What is the tertiary structure of a protein (full description)?
What does every protein have?
What two things is this responsible for?
What is the tertiary structure held together by?
What does this depend on?
Describe the following bonds in tertiary structures:
Hydrogen bonds
Ionic bonds
Sulphur bridges
What is the quaternary structure of a protein (full description)?
Describe the quaternary structure of haemoglobin in full as an example?
A description of the way the whole chain (including the secondary structure) folds itself into its final 3-dimensional shape (often simplified into models)
A unique tertiary structure
Its properties and function
Bonds between the R groups of the amino acids in the protein
What the sequence of amino acids is
Which are weak
Between R groups with positive or negative charges which are quite strong
Covalent S-S bonds between two cysteine amino acids, which are strong
Found in proteins containing more than one polypeptide chain. The individual polypeptide chains are usually globular, but can arrange themselves into a variety of quaternary shapes
The oxygen-carrying protein in red blood cells, consists of four globular subunits arranged in a tetrahedral (pyramid) structure. Each subunit contains one iron atom and can bind to one molecule of oxygen.
What does primary, secondary, tertiary and quaternary all refer to in proteins?
What does fibrous and globular refer to in proteins?
What are the two properties of fibrous proteins?
What are some examples of this?
What are the two properties of globular proteins?
What are some examples of this?
All refer tot he structure (shape) of proteins
Refer tot he function (job) of proteins
Fibrous proteins are tough and insoluble in water
Hair, nail, spiders web, collagen etc
Globular proteins are soluble in water and so can take part in chemical reactions
Antibodies, enzymes, hormones etc.
What is the structure of fibrous proteins like?
Describe this structure in full detail?
What is the structure of globular proteins like?
Describe this structure in full detail?
What does the dipeptide have?
What does this allow for?
Fibrous proteins tend to be dominated by beta sheet secondary structure
There are many bonds linking the sheets, so the proteins are strong and tough
In globular proteins, the secondary structure is folded to create a compact tertiary structure
This makes the protein more rounded in shape and means it can dissolve in water
Still has functional groups
The reaction can be repeated with another monomer.
