SfM - Proteins Flashcards
what is a protein?
macromolecule, made of amino acids, arranged in a particular structure to carry out a specific function
what do proteins do?
involved in biological processes
structural - actin=scaffold, keratin=skins
functional=enzymes/antibodies
how are amino acids made?
composed of either DNA or RNA nucleotides
DNA = a, c, g & t
RNA = a, c, g & uracil
Three nucleotides code for AAs
how many AAs are there in the body?
20
what is an amino acid composed of?
amine group and carboxylic acids. have a variable R group
are amino acids chiral?
yes, every aa except glycine has 4 different groups surrounding the carbon
are aa’s affected by pH?
low pH AA’s are cations (+)
high pH AA’s are anions (-)
what are aliphatic AA’s?
AA’s with hydrocarbon chain in R group
alanine, valine, iso/leucine
what are aromatic AA’s?
AA’s with benzene ring in R group
phenylalanine, tyrosine, tryptophan
sulphur-containing AA’s?
cysteine, methionine
basic AAs
long hydrocarbon chain that finishes in NH
arginine, lysine, histidine
acidic AAs
AAs have a C=O or C-O
aspartate, glutamate
polar AAs
AAs have carboxyl group in R group
serine, threonine, asparagine, glutamine
what is a proteins primary structure?
the sequence of AAs bonded in polypeptide chain
what is secondary structure?
the 3D spatial arrangement of AAs and their bonding (H-bond)
alpha helix
beta pleated sheet
what is the tertiary structure?
when functional groups (R chain) on AAs, interact with another - van der waals, ionic, hydrogen, disulphide, hydrophobic interactions
all functional proteins exist in this form
what is the quaternary structure?
every polypeptides interact with one another
haemoglobin contains 4 tertiary polypep structures and 4 iron containing heme groups
how does denaturation affect proteins?
chemical bonds in the protein are broken down - functionality is lost as it needs to be 3D (v.rare for denaturation to break primary structure)
what are the main functions of proteins?
structural, enzymatic, contractile, defensive, storage, storage, receptors, hormonal, transport
what is a glycoprotein?
proteins with 1 or more carbohydrates covalently attached
involved in stability, solubility, cell signalling
what is a lipoprotein?
proteins combine with fat/lipids to form lipoproteins
found in cell membranes, transport hydrophobic molecules
what is a metalloprotein?
protein molecules with a metal ion within their structures i.e haemoglobin
involved in enzymes, signal transduction, storage, transport
in what form can proteins exist?
globular, fibrous and membranous
globular proteins tend to be…
used in storage, hormones, transporters and structural
Myeloma is cancerous blood cells - globular proteins spill out
fibrous proteins tend to be…
involved in muscle fibres and connective tissue
Scurvy - lack of vitamin C means collagen can’t be created
membranous proteins tend to be…
membrane transporters, enzymes, cell adhesion molecules
Xanthelasma - LDL receptors not functioning or produced = lipid deposits under skin
