Lecture 11 - Introducton to Proteins Flashcards
some prokaryotes use ________ for _________ which are ______-_____ structures protruding from the cell surface
flagellum
locomotion
thread-like
why does the smooth ER look smooth and what is it rich in and for what?
because it lacks ribosomes, it is rich in enzymes for metabolic processes
ribosome composition:
composed of two subunits that combine to attach to messenger RNA (mRNA) and carry out protein synthesis
Cell types that synthesize large quantities of proteins have:
large numbers of ribosomes and prominent nuclei
lysosomes:
membrane-bound vesicles containing digestive enzymes
average protein molecule size:
1-5 nm
the word “Protein” is derived from the Greek word:
proteios which means “of the first rank” in order to emphasise the importance of this class of molecules
how many amino acids are there?
20
Transcription:
conversion of information from DNA to mRNA
Translation:
conversion of information from RNA to protein
protein chains always begin with:
Met (AUG)
generic zwitterion structure:
+H3N—CHR—COO-
each “r-group” has a different:
chemical property - large, small, positive, negative, hydrophobic, hydrophilic
that does the fact that R-Groups either want to be near or far from one another drive?
the affinity and repulsion of different interacting R-Groups drives protein folding
what can protein strands form?
helices, strands & coils
the diverse functions of protein:
enzymatic catalysis, transport, storage, mechanical support, immune protection, generation and transmission of nerve impulses, control of growth and differentiation, toxins, cascade proteins, antifreeze, GFP & adhesives
types of protein structure:
transmembrane, globular, fibrous & natively unfolded
globular proteins:
largest type of proteins
- Enzymes
- Immune system proteins
- Cell adhesion proteins
- DNA-binding proteins
- Carrier proteins
natively unfolded:
signalling peptides - neurotransmitters
representing protein structure:
- polypeptide chain - a chain of amino acids folds into a compact structure
- made up of distinct structural motifs
all amino acids exist as:
zwitterions
three forms of protein modelling:
(1) carbon backbone only
(2) + all side-chains
(3) Van De Waals- space filling
(4) secondary structure
all protein images are programmed via:
- a coordinate file from the “Protein DataBank” [PDB file]
- looks like a spreadsheet filled with data that is processed by an algorithm to build a three dimensional structure
- some column titles being: type no, atom acid, atom, amino acid, amino, x, y, z, occupancy & b-factor
how do proteins accomplish so many functions?
through forming a multitude of shapes, interacting with other molecules with high specificity
