PROTEINS
PROTEINS
- Created by: EClou
- Created on: 07-01-15 23:26
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- PROTEINS
- structural components
- Membrane carriers and pores e.g AT and FD
- enzymes, hormones and antibodies
- Amino Acids = monomer
- contain one acid end (e.g. COOH) and one amino end (e.g. NH2)
- 20 types
- R1=H=glycine R2=CH3=Alanine R3= C3H7=Valine
- central C atom with 4 bonds to hold together 2 ends, an H atom and the R group
- the link between AAs are called PEPTIDE BONDS and are formed by condensation reactions
- linked during protein synthesis in ribosomes
- forms a POLYPEPTIDE CHAIN
- broken by hydrolysis reactions
- DEAMINATION = how surplus AAs are removed form animal's bodies
- excess AAs become Toxic
- 2 AAs = DIPEPTIDE bond
- Structures
- Primary
- the sequence of AAs in the polypeptide chain
- Secondary
- polypeptide chains can fold into shapes depending on H bonds formed between the AAs
- if Alpha helix it COILS
- if Beta helix it PLEATS
- polypeptide chains can fold into shapes depending on H bonds formed between the AAs
- Tertiary
- further folding due to interaction betwn. AAs
- IONIC interactions: weak attractions betwn. pos.+neg. charges
- H bonds
- DISULPHIDE bonds: form betwn. SH groups on side group of Cysteine = covalent + strong
- HYDROPHOBIC + HYDROPHILIC: -phob- groups are close they clump, when -phil- groups are close they push apart
- Primary
- The breakage of Peptide bonds is catalysed by PROTEASE
- Shape relates to function
- Collagen
- Fibrous protein that that form supportive tissues and therefore must be strong
- 3 polypeptide chains tightly coiled in tripl helix
- insoluble
- metabolically unreactive
- repeating AA sequence
- Haemoglobin
- Globular protein with haem iron group that binds to O2 for transport
- roles up into ball-like structure
- means hydropilic on outside and hydrophobic on inside
- non-repeating AA sequence
- soluble and metabolically active
- 2 alpha + 2 beta chains
- Collagen
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