WK 4 (Macromolecules) Flashcards
(56 cards)
What constitutes most of the dry mass in cells?
Proteins
How are amino acids linked to form a protein? (what kind of bond)
Covalent peptide bond
The covalent bond between the carbon atom in the carboxyl group of one amino acid shares electrons with the nitrogen atom of amino group of another amino acid
- Water is released
Can rotation occur between amino acids?
Yes, covalent peptide bonds may allow rotation between amino acids (depending on the amino acids e.g. proline)
Can non covalent bonds form between atoms in polypeptide backbone and side chains?
Yes
Types of non-covalent bonds?
ionic bonds
Hydrogen bonds
Van der Waals attractions
Do bonds significantly affect the three dimensional structure of proteins?
Yes
Do hydrophobic and hydrophilic forces affect the structure of proteins?
yes, folding arrangement is affected
What is the primary structure of a protein?
The sequence of amino acids that make ups a polypeptide chain
What is the secondary structure of a protein?
The secondary structure is the way a polypeptide folds in a repeating arrangement to form α-helices and β-pleated sheets.
This folding is a result of hydrogen bonding between the amine and carboxyl groups of non-adjacent amino acids
Secondary structure provides the polypeptide chain with a level of mechanical stability (due to the presence of hydrogen bonds)
What is the tertiary structure of a protein?
The tertiary structure is the way the polypeptide chain coils and turns to form a complex molecular shape (i.e. the 3D shape)
It is caused by interactions between R groups; including H-bonds, disulfide bridges, ionic bonds and hydrophobic interactions
Relative amino acid positions are important (e.g. non-polar amino acids usually avoid exposure to aqueous solutions)
Tertiary structure may be important for the function of the protein (e.g. specificity of active site in enzymes)
What is the quaternary structure of a protein?
Structure formed by more than one polypeptide
Why is a proteins final conformation consistent?
It is guided by chaperone proteins
Ribosomal subunits are an example of what level of protein structure?
Quaternary structure
True or False
Different parts of proteins can fold differently
TRUE
Protein domains
Any part of a polypeptide chain that can fold independently into a compact stable structure
Usually contains between 50-350 amino acids
Different domains are often assigned to different functions
Fibrous proteins
Arranged in long chains or sheets
Globular proteins
Tightly folded into spherical or globular shapes
Ligand
the molecule to which a protein binds
Is protein binding an irreversible process?
No, overtime proteins and ligands will dissociate
The biological activity of proteins is only possible because of:
a) the number of disulphide bodies present
b) The repeatability of their tertiary structure
c) the glycosylation of proteins
d) none of the above
b)
Function of triacylglycerols
Stores of chemical energy
Most abundant lipid in cells
Triglycerides
Ester
Compound formed between an acid and alcohol reaction
How are triglycerides formed?
Through an ester linkage to glycerol to form triglycerides
