Proteins Flashcards
Function of proteins
make up large part of structures important for moving
Involved in defence mechanisms in our body
Some interact with carbohydrates and are important for cell to cell signalling
Polypeptide
Monomers put together
Covalently bound to each other through a condensation reaction
Primary structure
Unique sequence of amino acids
Secondary structures
Alpha helix: amino and carboxyl groups are attached by peptide bonds, r groups stick out from the helix
Beta sheets: made up of parallel protein strands with hydrogen bonds formed between the carboxyl and amino groups
Tertiary structure
Forms because of interactions between r groups
Quaternary structures
Association of different polypeptide subunits to form protein
Nuclear Membrane
Surrounds the nucleus and separates the cytoplasm from the nucleus
Endoplasmic reticulum
Special sequence allows ribosome to be bound to ER
Once the signal sequence occurs it binds a signal recognition particle receptor in the ER membrane
polypeptide can continue to be translated an can enter lumen of ER
Signal sequences are removed and polypeptide undergoes important changes
Some proteins stay in ER
Golgi apparatus
Proteins are transported in vesicles that pinch off from the ER
Able to fuse with the Golgi and deposit its contents in the lumen of the Golgi apparatus
Further protein modification occurs which could include adding a carbohydrate
Some proteins will continue to travel down endomembrane system
Lysosomes
Another place that the proteins can be transported to
Motor proteins
Can attach to a transport vesicle and then walk along the microtubules
SRP
Allows for the ribosome to bind to the SRP receptor on the ER membrane
Peptide is released into the ER for further modification
