y5 bio: cluster 1 (proteins)

generalised structure of proteins

1. hydrogen group (H+) [at top]

2. amine group (NH2) [at left/right side]

3. carboxyl group (COOH) [at right/left side]

4. R-group [at bottom]

how many different amino acids and their differentiating factor?

20 amino acids, R-group as differentiating factor

what are short chain of amino acids (up to 10) called?

oligopeptides

what is condensation reaction?

when 2 amino acids react to form dipeptide and water, and peptide bonds forms between carboxyl and amine group

what are the terminals in the dipeptide called?

n-terminals and c-terminals

what are essential amino acids (+ example)?

they cannot be synthesised by the body and can only be obtained by food. e.g. phenylalanine

how many essential amino acids in humans?

9

what are non essential amino acids (+ example)?

they can be synthesised by the body and are made from other amino acids. e.g. tyrosine, made from phenylalanine

animal proteins vs plant proteins (in amino acid aspect)

animal proteins have a complete amino acid profile, but plant proteins may lack specific amino acids

how many amino acids in a short peptide chain?

5 to 10

how many amino acids in a medium peptide chain?

100 to 200

how many amino acids in a very long peptide chain?

thousands…

how to calculate possibilities for a chain of X amino acids

20^X (number of amino acids available to you, to the power of the number of amino acids in one chain)

how do proteins get denatured?

heat or extreme pH, that break intramolecular bonds and changes protein’s shape, structure and function

R-groups can be categorised EQUALLY into 2 groups

hydrophobic and hydrophilic

hydrophobic R-groups can be further split into 3 groups

basic (accepts protons, positively charged), acidic (donates electrons, negatively charged), polar (forms hydrogen bonds)

which amino acid contains SH group?

cystenine contains disulphide bonds

which amino acid contains sulfur?

methionine

smallest and largest amino acid?

glycine smallest, tryptophan largest

2 main types of secondary structure of proteins

alpha helix and beta pleated sheet

how do hydrogen bonds form in both alpha helix and beta pleated sheet?

N-H and C=O groups interact

how does alpha helix look like, and where are the hydrogen bonds located?

right handed spiral, hydrogen bonds between adjacent turns

beta pleated sheets can be further categorised into

parallel and anti-parallel

how does beta pleated sheets look like, and where are the hydrogen bonds located?

parallel/anti-parallel polypeptide sections, hydrogen bonds between chains

4 types of bonds in tertiary structure

1.hydrogen bonds

2. ionic bonds

3. disulfide bonds

4. hydrophobic interactions

hydrogen bonds form between?

amino acids with polar R-groups

ionic bonds form between?

amino acids with charged R-groups

disulfide bonds form between?

cysteine amino acids

hydrophobic interactions form between?

amino acids with non-polar R-groups

out of the 4 types of bonds in tertiary structure, rank the strongest to weakest?

disulfide bonds, ionic bonds, hydrogen bonds and hydrophobixc interactions

how is protein embedded in the membrane?

amino acid deteermines its location, where polar amino acids interact with water and non-polar amino acids avoids water

how many proteins make quaternary structure?

2 or more POLYPEPTIDES linked tgt make quaternary protein

2 types of proteins (composition)

conjugated (polypeptides + non protein groups) and non-conjugated (ONLY polypeptides chains)

examples of conjugated VS non-conjugated

insulin with 2 chains (conjugated), haemoglobin with 4 polypeptides and 4 heme groups (non-conjugated)

what structure of protein is collagen?

it is considered in the quaternary structure, as it has 3 polypeptides linked tgt and has a high tensile strength to resist stretching

2 types of proteins (shape)

globular and fibrous

polypeptides in globular VS fibrous proteins

folded (globular), unfolded (fibrous)

shape of globular VS fibrous protein

round and compact shape (globular), narrow and elongated (fibrous)

solubility of water in globular VS fibrous protein

water-soluble (globular), insoluble in water (fibrous)

amino acids sequences in globular VS fibrous protein

non-repetitive (globular), repetitive (fibrous)

roles in globular VS fibrous protein

regulatory roles (globular), structural roles (fibrous)

globular proteins functions

they have diverse functions, with antibodies having immune function, haemoglobin having transport function and enzymes having catalytic function

fibrous proteins function

to withstand tension forces and provide structural support

defintion of primary structure of proteins

amino acid sequence

definition of secondary strucrture of proteins

egular patterns stablised by hydrogen bonds

definition of quaternary structure of proteins

multiple polypeptides linked tgt