Topic 1: Proteins Flashcards
True or false: proteins are the most important biological molecule for living organisms
False-after water, proteins are the next major biological molecule in living organisms
What monomers make up proteins?
Amino acids
What chemical elements do amino acids contain?
Carbon,hydrogen,oxygen and nitrogen
Some amino acids contain sulphur
Name the 4 different components that make up amino acids
- Amine group
- Carboxyl group
- Carbon-containing side chain or R group
- Hydrogen atom
How many types of amino acids are there in the body?
20
What makes amino acids different from each other?
The R groups
What is the bond between amino acids called?
Peptide bond
What is formed when 2 amino acids are joined together?
Dipeptide
What is it called when dipeptide or more than 2 amino acids join together?
Polypeptide
What are the 4 different levels of protein structure in order?
Primary
Secondary
Tertiary
Quaternary
What controls the structure of different proteins?
Genes
What is the structure of a protein determined by?
The number and position of amino acids
What is the primary structure?
The sequence of amino acids
When many amino acids join together by condensation reactions to form a polypeptide chain
What can happen as a result of changes in the amino acid sequence (primary structure)?
Changes in the tertiary structure which can affect its ability to function
Why can changes in the primary structure affect the tertiary structure of a protein, and its ability to function?
Bonds that form between R groups of different amino acids form in different places
True or false: all proteins are made of a singular polypeptide chain?
False: some may be a singly polypeptide chain but most are made up of more than one
How is the secondary structure of proteins formed?
When hydrogen bonds form between amino acids
In secondary structure, hydrogen bonds form. Give an example of where the bonds form and why
Between the amine group and the carboxylic acid group
Because the amine group is negatively charged and the carboxyl group is positively charged
What structures are produced in secondary structure as a result of hydrogen bonding?
Alpha helix or beta pleated
How is tertiary structure formed?
By interactions between the R groups of amino acids
Secondary structure can result in alpha helices or beta pleated. What happens to alpha helices in tertiary structure?
They can be twisted and folder further to create more complex and unique 3D structures
How are tertiary structures maintained?
By different bonds forming between the R groups
What bonds can form between R groups in tertiary structures?
Hydrogen bonds, ionic bonds, disulphide bridges
Where do ionic bonds form in tertiary structure?
Between carboxyl groups and amino groups
They aren’t involved in a peptide bond
Describe how easily the bonds in tertiary structure can be broken
Hydrogen bonds- numerous but easily broken
Ionic bonds- weaker than disulphide bridges and can be easily broken by changes in PH
Disulphide bridges- strong so aren’t easily broken
What is formed as a result of more bonds in tertiary structure?
Hydrophobic and hydrophilic regions
What does tertiary structure mean for proteins that are made from a single polypeptide chain?
Tertiary structure forms their final 3D structure, they don’t have quaternary structure
Why is the tertiary structure important?
It forms the specific shape of the protein e.g. enzyme active site, due to the bonding between the R groups of different amino acids
What is the quaternary structure of proteins?
The protein structure when more than one polypeptide chains are combined together and bonds are formed between them
Give 3 examples of proteins with quaternary structure
Haemoglobin
Antibodies
Protein receptors
What are the 2 kinds of proteins?
Fibrous and globular
What are fibrous proteins?
Fibrous proteins that have polypeptides that join together to form long fibres or sheets
They consist of long chains running parallel to one another and are held together by cross-bridges
What is the main function of fibrous proteins and can you describe a property of them
- structural function
-strong and are insoluble in water
Give 2 examples of fibrous proteins and where they are found in the body
Keratin: fingernails and hair
Collagen: skin,bone,blood vessels and teeth, it is found in tendons which join muscles to bones
Describe each structure level of the fibrous protein: Collagen
Primary- amino acids join to = polypeptide chain
Secondary- alpha-helix
Tertiary- alpha-helix is twisted to form a second helix
Quaternary- three similar polypeptides are wound together like rope which gives molecule the strength
How are globular proteins different to fibrous?
-have a more spherical shape rather than long sheets
-biochemical function not structural
-they are soluble in water
Give 3 examples of globular proteins
-enzymes
-channel proteins in cell membranes
-haemoglobin
