Proteins Flashcards
What do amino acids consist of ?
- Carbon
- Amino group (H2N)
- Carboxyl group (OCOH)
- Hydrogen
- Side chain (R)
What does an atom consist of ?
Nucleus & electrons
How is a covalent bond formed between 2 atoms?
Share electrons
What is bond polarity ?
Uneven electrons share
What atoms in an amino acid are involved in polarity ?
Nδ- , Oδ- Cδ+ , Hδ+
What happens when rather than sharing electrons, atoms gain or lose them ?
- Ions: positive , lost electrons
- Ions: negative, gain electrons
Which atoms in an amino acid are often positively and which negativeley chraged?
N+ O-
They’re 5
What groups are amino acids divided in based on properties of their side chains ?
- Polar/ Non-polar
- Hydrophillic/Hydrophobic
- Acidic/Basic
- Ionisable/charged
- Special amino acids
What is the polar and non polar group about ?
Polar
* Uneven share of electrons in bond
* Electronegative stoms “pull” electrons of a bond towards them
Non-polar
* Even electroons share
What is hydrophilic / Hydrophobic?
- Polar side chains are Hyrophillic: they like water
- Nonpolar side chains are hydrophobic: they don’t like water
What is acidic and base?
- Acidic groups yield H+ to solution
- Base groups remove H+ from solution
- pH = -log H+concentration
- Higher H+, lower the pH, hence acids have low pH and bases high pH
What does ionisable and charged mean?
- Ionisation = to add or remove electrons
- charged = positive or negative
What are the chraged amino acids?
Negatively charged amino acids:
*aspartic acid
* Glutamic acid
Positively charged amino acids :
*Lysine
*Arginine
*Histidine
What are special amino acids ?
- Cysterine has sulfhydryl (SH) that can for s-s bonds
- Glycine has H (very small)
- Proline is cyclic
What type of bonds are formed between amino acids?
Peptide bonds
What type of bonds are formed between amino acids?
Peptide bonds
What are dipole-dipole interactions?
When opposite poles attract
What is hydrogen bonding?
- It’s a type of dipole-dipole interaction involving hydrogen
- Amino acids can be hydrogen bond **donors ** or acceptors
When can hydrogen bonding occur ?
It can occur between pepetide bonds in the same region chain
Secondary structure involves hydrogen bonding between atoms associated with….
- R groups
- C-termini
- N-termini
- Cysteines
- Peptide bonds (pole attraction)
What is Van der Waals interactions ? (non-covalent bonding)
non polar
* even electron share
* But temporaray dipole
* only involves non polar chains
What is hydrophibicity ?
- Polar side chains are hydrophillic (like water)
- Nonpolar side chains are hydrophobic (don’t like water)