Chapter 4 Flashcards
structural proteins
provides cell with shape and structure
enzymes
catalyze covalent bond breakage or formation
transport protein
carries other molecules or ions
motor protein
generates movement in cell and tissue
storage protein
stores small molecules or ions
signal protein
carries signal from cell to cell
receptor protein
detects signals and transmits them to cells response machinery
gene regulatory protein
binds to DNA to switch genes on or off
what bonds link amino acids?
peptide bonds
what is protein made of?
amino acids linked together into polypeptide chain
what 3 noncovalent bonds help proteins fold?
hydrogen bonds, electrostatic attractions, van der waals attraction
what interaction is most important for protein folding?
hydrophobic interaction
what causes proteins to denature?
urea. denature proteins unfold to natural shape
how are prion diseases caused?
by rare proteins whose misfolding is infectious.
what is a common folding pattern?
alpha helix
alpha helix
the amino group of every peptide bond is h-bonded to carboxyl group of neighboring peptide bond located 4 amino acids away.
what is another common folding pattern of proteins?
beta sheets
beta sheet
individual strands in sheet held together by h-bonding between peptide bonds in different strands.
what are the two varieties of beta sheets?
parallel and Antiparallel
what is comprised of a family of proteolytic enzymes?
serine proteases
many protein molecules contain _____ of a single protein subunit.
multiple copies
proteins can assemble into what?
complex structures. dimer, helix, and ring
what is an actin filament composed of?
identical protein subunits
single protein subunits can pack to form what?
a filament, tube, or a spherical shell
what is a collagen?
a triple helix formed by 3 protein chains to wrap around one another
what do disulfide bonds do?
help stabilize a favorable protein confomation
folding of a polypeptide chain creates what on protein surface?
cavity
binding sites allow proteins to do what?
interact with specific ligands.
what is an antibody?
y-shaped and has two identical binding sites for its antigen.
what is feedback inhibition?
regulates the flow through biosynthetic pathways
what does feedback inhibition do?
triggers a conformational change
what does an increase in ligand (ADP) concentration do?
activates the enzymatic reaction for oxidation of sugars
what conformation can ADP bind to? why?
closed. lowers energy of closed conformation, locking enzymes in the active site
What is a common mean of regulating protein activity?
protein phosphorylation
what does GTP-binding proteins from?
molecular switches.
an allosteric motor protein driven by ATP hydrolysis moves in what direction? why?
one direction. repeated cycles of conformation changes, the proteins moves continuously
how is protein behavior controlled?
modification of a protein at multiple sites produce a regulatory code that controls the PB
how can the structure of protein be determined?
x-ray crystallography
cells in culture display properties that reflect what?
their origin
what is affinity chromatography used for?
to isolate the binding partners of a protein of interest
