Proteins Flashcards
What are the building blocks for proteins?
Amino acids
What are proteins made of?
Polymers built from monomers
What are monomers?
Amino acids
Do amino acids store excess amino acids for later use like fat and carbohydrates?
No
What are proteins essential for?
Cell function
Enzymes
Structural
Transport
Movement
Defence
Surface Receptors
Carriers
What are the five basic parts of amino acids?
- Central carbon - alpha
- A hydrogen atom
- An amino acid group
- A carbonyl group
- An R group - side chain
What is different in each amino acid?
The R group
What two sterioisomers does amino acids (not glycine) exist as?
L-form and D-form
What determines the isometric shape?
The distribution of atoms around the central carbon atom
What isomer is amino acids found?
L-form
What gives amino acids different physiochemical properties?
Different R groups
Can some amino acids ionize to carry negative or positive charges?
Yes
Does the polarity of an amino acid influence how it interacts with water?
Yes
What is the meaning of polar?
Two parts with opposite charges
Water loving
Hydrophilic
What is the meaning of nonpolar?
No opposing charges
Water hating
Hydrophobic
What do amino acids (monomers) join together to form?
Polymers
What reaction is a molecule of water lost in?
A condensation reaction
A peptide bond is the strongest form of what bond?
A covalent bond
What forms when two amino acids joined together?
A dipeptide
What forms when many amino acids are joined together?
A polypeptide
Where does the bond form?
Between the carboxy group of one amino acid and the amino group from another amino acid
What are the four levels of a protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
What is the definition of a primary protein structure?
The sequence of amino acids, joined by peptide bonds
It is the primary structure of a protein
What is a secondary protein structure?
An alpha helix
A beta pleated sheet
Random coil
Htydrogen bonding betwenn carbonyl group of one amino acid and amino group of another
Where is the secondary protein structure found?
Myosin in muscle
Keratin in hair and nails
Does large R groups cause the helix to be stable or unstable?
Unstable
What are some globular protein structures?
Myoglobin - iron and oxygen binding protein found in muscle tissue
Haemoglobin - iron and oxygen binding protein in blood
Triose phosphate isomerase - catalyses coversion of triose phosphate isomers
20s proteasome - degrade unneeded or damage proteins by proteolysis
Is the beta pleated sheet more extended than the alpha helix?
Yes
What is made by silkworms and spiders?
Silk Fibroin
What is formation of silk fibroin?
Array of antiparrallel beta pleated sheets
Each beta strand has alterning Glycine and Ala or Ser residues
How are beta sheets connected?
The beta turn
What does the beta turn consist of?
Four amino acid residues
How is the beta turn stabalised?
By hydrogen bonding between Carbonyl oxygen of the first residue and the amide hydrogen of the fourth residue
What is also part of the beta turn?
Glycine and Proline
What is the structure of loops and coils?
Disordered and flexible
What do coils and loops connect?
Secondary structure elements
Is there a common pattern in loops and coils?
No
Not like beta turns
What group are tertiary structures involved in?
R groups
Side chains
What are valine side chains?
Hydrophobic side chains
What is an example of hydrogen bonds between groups in side chains?
Serine
Can ionic charged side chains form ionic bonds?
Yes
What bonds can sulphur containing grouos form?
Covalent bonds
What are prions?
Misfolded proteins which are found in several fatal neurodivergent diseases
