What role do amino acids play in protein structure?
They are the monomers from which proteins are made.
AQA A-Level Biology - (7402) · 3.1.4.1
Revise AQA A-Level Biology - (7402) specification point 3.1.4.1, General properties of proteins, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What role do amino acids play in protein structure?
They are the monomers from which proteins are made.
What four groups or atoms are bonded to the central carbon of an amino acid?
An amino group (), a carboxyl group (), a hydrogen atom, and a variable side chain ().
What structural feature differs among the twenty amino acids commonly found in proteins?
Their side chains.
How do amino acid side-chain properties relate to protein properties?
Side-chain properties contribute to the properties of the proteins containing them.
How is a peptide bond formed between two amino acids?
A condensation reaction joins the amino group of one amino acid to the carboxyl group of another, releasing water.
What is formed when two amino acids undergo condensation?
A dipeptide.
How is a polypeptide chain formed from amino acids?
Repeated condensation reactions join many amino acids together.
How many polypeptide chains can make up a functional protein?
One polypeptide or more than one polypeptide.
What is the primary structure of a protein?
The amino acid sequence of its polypeptide chain or chains.
What is the secondary structure of a protein?
Local folding of a polypeptide, including alpha helices and beta-pleated sheets.
What stabilises protein secondary structure?
Hydrogen bonds.
What is the tertiary structure of a protein?
The overall three-dimensional shape of a polypeptide, arising from further folding and side-chain interactions.
Which three types of bond or bridge contribute to stabilising protein tertiary structure?
Hydrogen bonds, ionic bonds and disulfide bridges.
What is the quaternary structure of a protein?
The arrangement of multiple polypeptide chains in a protein containing more than one chain.
Why does amino acid sequence influence protein folding?
Different amino acid side chains can form different interactions.
How do a protein’s shape and chemical properties support its function?
They determine how the protein interacts with other molecules.
What are three functions proteins can carry out?
Catalysis, transport and structural support.
What type of bond does the biuret test detect when testing for proteins?
Peptide bonds.
How is the biuret test carried out on a sample?
Make the sample alkaline with sodium hydroxide, then add copper sulfate solution.
What colours indicate positive and negative biuret test results?