2.4 proteins Flashcards
what are proteins?
proteins are POLYMERS made from AA (which are the monomers)
what determines the properties of proteins?
determinded by the R group on the AA
H
l
amino group – C – carboxyl group
(NH2) l (COOH)
R
How many common (made by ribosomes) AA are there
20
RECALL HOW TO DRAW PEPTIDE BOND FORMATION
carboxyl grp from AA + amino grp from AA – dehydration recation –> peptide bond between C=O and N-H + H2O
how are amino acid polypeptide sequences arranged
- prod in ribosomes
- AA linked tgt in sequence dictated by genes (sequences of DNA carrying info for expression)
what are the bare bones of the process from DNA to polypeptide production
DNA –transcription–> RNA –translation–> polypeptide
what is the start codon?
AUG
What are the stop codons
UAA
UAG
UGA
what are the 4 levels of protein structure?
- primary
- secondary
- tertiary
- quaternary
what is primary protein structure
a sequence of AA along the polypeptide chain (w peptide bonds), determined from genetic info
what is secondary structure of a protein
- parts of polyp chain COIL onto itself, forming ALPHA HELICES
- other parts can fold into BETA PLEATED STRUCTURE
- stabilised by HYDROGEN BONDS btw AA
what is tertiary protein structure
- overall THREE DIMENSIONAL SHAPE of a protein
- from bonds formed between R groups
- eg. disulphide bridge betw 2 sulfur-containing AAs
what is quarternary structure of protein
- when 2 OR MORE polypeptide chains ASSOCIATE to form resultant protein
- not all proteins
- eg collagen (triple helix), haemoglobin (4 polyp chains)
are all enzymes proteins?
no! some enzymes are made of RNA.
protein function: enzymatic
its just an enzyme man cmon lock and key
substrate in active site then products
proetin function: storage, 2 examples
examples
- egg albumin
- casein in milk (makes it white)
protein functions: hormonal, 3 ex
- insulin
- glucagon
- adrenaline
protein function: contractile and motor, 2 ex
both found in muscle cells
- actin
- myosin
protein functions: defensive, 1 ex
antibodies – clump onto bacteria
protein functions: transport, 1ex
electron transport chain proteins
protein functions: receptor
on plasma membrane, receives signal molecule –> relay molecules –> response
protein function: structural, 1 ex
collagen
define PROTEOME
the sum of all proteins that can be produced by the species
define GENOME
the sum of all genes encoded within the DNA of that species
what is the proteome dependent on?
- genome of the species
- environment
rubisco full name
ribulose bisphosphate carboxylase
what does rubisco do? 2
it is an ENZYME
- used to FIX CO2 from atmos (part of calvin cycle)
- provides SOURCE of carbon during psis + formation of complex C compounds
where is rubisco found?
its an ENZYME found in high conc in leaves of plants
what is insulin?
a hormone, used to reg blood glucose levels – secreted in response to HIGH glucose levels, prod by pancreas
what are immunoglobins 3
- also known as antibodies
- 2 antigen binding sites per protein
- diff antibodies have diff antigen binding sites – specific
- can also bind to antigens on bacteria
what do antibodies bind to?
ANTIGENS
what do antibodies do to bacteria
AGGLUTINATE
- not able to cause infections
- clumped tgt = engulfed by WBC (phagocytosis)
what is rhodopsin?
its visual purple 💜💜💜
- pigment that can absorb light
- found in receptor cells in retina
what happens when a photon reaches a rhodopsin molecule?
isomerisation occurs – change in molecule shape
what is collagen?3
- structural protein, TRIPLE HELIX
- forms a mesh = resistance against tearing and shearing
- structural strength
spider silk as a protein ??
- what it says on the tin. forms webs
- fibres can extend when streched
- stronger than steel cables
denaturation of proteins by HEAT 3
- heat energy incr vibration of atoms
- vibration breaks weak internal bonds
- affects 3d shape
low – low activity
high – denatured
denaturation of proteins by pH 3
- extreme pH changes CHARGES of R GRPS
- breaking of ionic bonds
- changes to protein shape
low/high – dentaured
