Protein Structure And Function Flashcards
How are proteins useful to the cell?
They provide both structural and functional molecules that underlie the dynamic processes of the cell
What are some carrier functions of protein?
Trafficking oxygen, importing and exporting molecules and other ions
What are some metabolic functions of protein?
Enzyme cascades producing utilising energy eg: glycolysis
Where do proteins form part of the cell machinery ?
Spliceosomes
Where do proteins make up the structural scaffolding?
Micro tubules and nucleosomes
When do proteins act as sensor molecules?
Receptors on cell surface
Describe amino acid structure
Tetrahedral arrangement of atoms with the alpha carbon at its centre.
Carboxyl and amine groups attached to a central carbon .
A variable side chain R confers the specific physiochemical properties.
A hydrogen .
What happens when the amino acid acts as a base ?or acts as an acid ?
Base: NH2 ionises to NH3+
Acid: COOH ionises with the loss of H to become COO-
In excess H+ and excess OH-
Name the intermediate
Excess H+ amino acid acts as a base and accepts the H+
Excess OH- amino acid acts as acid with loss of H+
In neutral pH….intermediate = zwitterion
Name the 2 amino acid isomers
Dextro and levo
Describe the arrangement around the alpha carbon…what is the exception?
The arrangement around the alpha carbon is said to be asymmetric or chiral except glycine which has R group of H
In what direction when viewed along the hydrogen-ca bond will the L & D form read CORN?
L-form-clockwise
D-form- anti-clockwise
Where do you find amino acids in the L form and amino acids in the D form?
L form : incorporated into proteins by all living organisms
D form: cell walls in bacteria and some therapeutics
Define residue
Each repeating unit of a polypeptide chain
Why is the variable side R usually arranged in a trans confirmation ?
0.1% peptide bonds have a less energetically favourable vis arrangement
