3.1.4 Proteins Flashcards
There are …different amino acids that can be used to form polypeptides
20
A condensation reaction between 2 amino acids forms…
Dipeptide and water
A condensation reaction between …amino acids forms a dipeptide and water
2
A…reaction between 2 amino acids forms a dipeptide and water
Condensation
A dipeptide and 1 molecule of water are hydrolysed to form…
2 amino acids
Name for bond between 2 amino acids in dipeptide
Peptide bond
During the condensation of 2 amino acids to form a dipeptide and water a …bond is formed between the 2 amino acids
Peptide
H2N is known as the…group
Amine
True or false, when drawing an amino acid the H must always go on the top and the R must always go on the bottom
False
The R and H can go either way round
But the amine group (H2N) must always go on the left and the carboxylic acid (COOH) must always go on the right
The…group of the amino acid determines which amino acid it is
R
(The R group is variable as it can change but the rest of the amino acid never changes)
Which part of the amino acid is variable so can change
R group
(The R group determines which amino acid it is)
Dipeptides are formed by the condensation of…amino acids but polypeptides are formed by the condensation of many amino acids
2
When we call it a polypeptide vs protein
Polypeptide= 1 polypeptide chain
Protein= multiple polypeptide chains
Amylase is made up of only 1 polypeptide chain therefore it’s called a …(protein/ polypeptide)
Polypeptide
Haemoglobin is made up of 4 polypeptide chains so it’s called a …(protein/ polypeptide)
Protein
Instead of saying that the amino acid sequence effects the shape of the polypeptide/ protein, we say that the amino acid sequence effects the…of the polypeptide/ protein
Tertiary structure
Tertiary structure of protein/ polypeptide is determined by bonds between …
R groups
The …of proteins/ polypeptides is determined by bonds between R groups
Tertiary structure
3 examples of bonds between R groups in the polypeptide/ protein that determine its tertiary structure
Disulphide bridge
Ionic bonds
Hydrogen bonds
There are…levels of protein structure in the hierarchy
4
(However the 4th level only applies to proteins and not polypeptides as it involves more than 1 polypeptide chain)
Primary structure of protein meaning (although technically it should be called primary structure of polypeptide)
Sequence of amino acids in polypeptide chain
The sequence of amino acids in the polypeptide chain is known as the…structure
Primary
Secondary structure of proteins meaning (although technically it should be called secondary structure of polypeptides)
Some regions of the polypeptide chain fold in a specific way to form an alpha helix or beta sheet and there are hydrogen bonds between the C=O and N-H of different amino acids which stabilises the structure
When talking about secondary structure, we talk about …bonds
Hydrogen
In the secondary structure…bonds stabilise the structure
Hydrogen
In the secondary structure of protein, hydrogen bonds refer to bonds between … and…of different amino acids
C=O
H-N
Is secondary structure 2D or 3D
3D
Tertiary structure of protein (although technically it should be called tertiary structure of polypeptide) is held together by a number of different bonds between the…groups
R
In the…structure, different polypeptide chains are held together by disulphide bridges/ ionic bonds/ hydrogen bonds (same type of bonds as for tertiary structure)
Quaternary
When carrying out the biuret test for proteins, the test solution must be…(acidic/ alkaline)
Alkaline
(Biuret reagant contains sodium hydroxide which is alkaline)
To test for proteins you either add biuret regant to the test solution or sodium…(which is alkali) and copper…solution (which is blue)
Hydroxide
Sulphate
True or false, functional proteins are always made up of one polypeptide chain
False
They may contain one or more polypeptide chain (some functional proteins like amylose are only made up of one polypeptide chain but Haemoglobin for example is made up of 4 polypeptide chains)
