Module 5 (Protein Structure, Function and Synthesis) Flashcards
N-Terminus
The end of an amino acid chain that has the amino group
C-Terminus
The end of an amino acid chain that has a carboxyl group
mRNA
Messenger RNA
tRNA
Transfer RNA
What’s the difference between Basic and Acidic amino acids?
Basic: has amine group (usually + charge)
Acidic: has carboxylic acid in the side chain (usually - charge)
Hydrophobic Amino Acids
Hydrophobic R groups, weak van der Waals forces
Hydrophilic Amino Acids
Contain electronegative elements (N or O), unequal charge -> R group interact with each other or H bonding
Typically found on the “outer” surface of proteins
Why is Glycine a special amino acid?
R group is Hydrogen, small and nonpolar, increases flexibility of the polypeptide backbone
Why is Proline a special amino acid?
R group links back to the amino group, restricts rotation of the C-N bond, limits the protein folding around proline
Cysteine
R group contains a -SH group, two cysteines can form a disulfide bond (cross bridge, which can connect different parts of the same protein or different proteins together)
Levels of Protein structure
Primary, Secondary (2°), Tertiary(3°), Quaternary (4°)
Primary Structure
Linear sequence of amino acids that make up a polypeptide chain
- Amino to carboxyl (N-terminus to C-terminus)
- R-groups alternate position of either side of the amino acid chain
Secondary Structure
Conformation of portions of the polypeptide chain (alpha helix and beta sheet)
Alpha Helix
- Very stable
- Right-hand helices
- Formed from H-bonds to the 4th amino acid neighbour (functional groups)
Beta Sheet
- Pleated formation
- Can be parallel and antiparallel
- Stabilized by H-bonds (functional groups)
Tertiary Structure
- Conformation of the entire protein
- How regions of 2° conformations are oriented
- Functional form
- Determined by R-group interactions
R-group Interactions
- Spatial distribution of the hydrophilic and hydrophobic R groups
- Chemical bonds and interactions that form between the R groups (include hydrogen bonds, hydrophobic bonds, ionic bonds, disulfide bonds)
Disulfide bonds
Covalent bond between two cysteine residues
Quaternary Structure
The arrangement of multiple subunits of polypeptides, also R-group interactions
Homodimer
Protein containing two identical subunits
Heterodimer
Protein containing two non-identical subunits
Components of Translation
mRNA, Ribosome, tRNAs, Aminoacyl tRNA synthetases, Initiation factors, elongation factors and release factors
Ribosomes
Location of translation, protein factories, small subunit and large subunit
- Reads mRNA 5’-3’
Codon
Three adjacent nucleotides, specifies the placement of an amino acid
