General Properties Of Proteins Flashcards
What are proteins made of?
Amino acids
Which 4 elements are always present in proteins?
Carbon
Nitrogen
Hydrogen
Oxygen
How many different amino acids are there commonly found in organisms?
20
In what 4 ways are amino acids the same?
Amino group
Central carbon
Hydrogen atom
carboxyl group
In what ways are amino acids different?
Variable group
When R= H what is the amino acid called?
Glycine
When R= CH3 what is the amino acid called?
Alanine
Primary structure
The number and sequence of amino acids
What is the name of the bond that joins 2 amino acids together?
Peptide bond
What causes a chain of amino acids to fold?
Positive and negative charges on the r groups of different amino acids cause unlike charges to attract each other
Features of r groups of amino acids
- Can be positively or negatively charged
- can be hydrophobic or hydrophilic
- they have a second amine or carbonyl group in their r group
How can we use the properties of the r groups of amino acids to separate out individual amino acids when they are in a mixture?
Chromatography
How can we identify the separated amino acids on a chromatogram?
Calculate the retardation factor
Secondary structure
The folding of polypeptide chains due to hydrogen bonds forming between the -NH and =O of peptide bonds between amino acids
Alpha helix
Beta pleating
Tertiary structure
Polypeptide chain can be further folded to form a more complex, specific, SD structure
Hydrogen bonds, disulfide bridges and ionic bonds → mainly between r groups of different amino acids in the chain
Hydrogen bonds
Individually weak bonds but lot5 gives the structure stability
disulfide bonds
Strong bonds
Occur between two sulphur atoms found in the r groups
Ionic bonds
Form between carboxyl groups and amino groups that have not been used to form the peptide bonds
Can be found at either ends of polypeptide chains or on the r group of some amino acids
These bonds are easily broken by changes in pH
diamino amino acids
dicarboxy amino acids
Quaternary structure
More than one polypeptide chain
Conjugated proteins
Consists of polypeptide chains plus a non protein part (prosthetic group)
Prosthetic group in haemoglobin
haem
Contains an iron ion
fibrous/ fibrillar proteins
- Form long chains with individual chains running parallel to each other
- linked by many cross bridges
- quaternary structure
- structural functions
- insoluble
Globular proteins
- Most tertiary structure
- rounded 3D structure shape
- relatively soluble
- metabolic functions
Functions of proteins
- Antibodies
- muscle proteins
- structural proteins
- Transport proteins
- protein synthesis
- membrane proteins
- hormones
