Chapter 3 Protein Structure and Folding Flashcards
20 distinct building blocks of proteins (actually 22)
amino acids
the central carbon on an amino acids binds to these 4 structures:
H - hydrogen atom
NH2 - amino functional group
COOH - carboxyl group
distinctive “R” group, or side chain
in water, amino acids…
ionize
in water, the carboxyl group on an amino acid…
acts as an acid
in water, the amino group on an amino acid…
acts as a base
what makes the 20 amino acids unique from each other? Why?
the distinct R group, or side chain
it causes variation in properties
properties of polar and electrically charged R groups:
interact readily with water and are hydrophilic, dissolve readily in water
properties of non-polar R groups:
lack highly electronegative atoms capable of reacting with water
hydrophobic, coalesce in aqueous solution instead of dissolving
if the R group has a negative charge:
it is acidic and will lose a proton
if the R group has a positive charge:
it is basic and will pick up a proton
building blocks of polymers
monomers
if the R group is uncharged
A. with an oxygen
B. without an oxygen
A. the electronegative oxygen will form a covalent bond within the R group, making it an uncharged polar amino acid
B. its a non polar amino acid
meaning of monomer
one part
macromolecules
large molecules made up of smaller molecule subunits joined together, made up of monomers
monomers linking together:
polymerization
amino acids are the ______ that polymerize to form _____
monomers, proteins
monomer in, water out, occurs in a ________ reaction
condensation
water in, monomer out, occurs in a ________ reaction
hydrolysis
monomers polymerize through what type of reaction?
condensation reactions/dehydration reactions
polymerization
bonding together of monomers
bond between the amino group and the carboxyl group of two acids
peptide bond
R group orientation in the peptide backbone:
the R groups extend out from the back bone, can react with other R groups and water
directionality in the peptide backbone:
amino group on one end (N terminus), carboxyl group on one end (C terminus)
flexibility in the peptide backbone:
the bond on either side of the peptide bond can rotate, so the molecule is flexible
polymer with less then 50 amino acids
oligopeptide, or peptide
oligopeptide
few peptides
polymer with mire than 50 peptides
polypeptides
polypeptides
many peptides
proteins are ____ made up of _________
proteins are polymers made up of amino acids
Primary structure of proteins is determined by ____ and ______
peptide bonds and the unique sequence of amino acids that make up the protein
Changes in primary structure affect:
protein function
Types of bonds that support secondary structure?
hydrogen bonds
two possible secondary structures:
alpha helicies and beta pleated sheets
a proteins 3 dimensional shape is determined by its:
tertiary structure
5 types of bonds that affect tertiary structure
- hydrogen bonding
- hydrophobic interactions
- van der waals interactions
- covalent bonding (disulfide bonds)
- Ionic Bonding (between charged groups)
A combination of polypeptide subunits results in:
quaternary structure
macromolecular machines
groups of multiple proteins that assemble to carry out a function
dimer
protein consisting of 2 identical polypeptide subunits
tetramer
protein consisting of 2 sets of identical polypeptide subunits
how are folding and function related? what happens when a protein is denatured?
folding is crucial to function, denaturing a protein breaks disulfide and hydrogen bonds and keeps proteins from working properly
which proteins facilitate protein folding?
molecular chaperones
do proteins only have one shape?
no, proteins are somewhat flexible and dynamic, until they are prompted into their functional form
Stanley Prusiner on protein folding
some proteins are induced to fold into disease causing , infectious agents called prions
side effect of prions in several mammals
brain degeneration
proteins that catalyze are called:
enzymes
proteins that attack and destry viruses are called:
antibodies
_____ _______ are responsible for the movement of the cell, and moving large molecules within the cell
motor proteins
proteins are involved in ________ from cell to cell around the body
carrying and receiving signals
_______make up body component like skin and nail and form the internal skeleton of cells
structural proteins
catalyzed reactions involve one or more reactants called :
substrates
enzymes hold substrates in the exact orientation…
to that they can react
Emil Fischer’s idea
lock and key model of enzymes and substrates
where substrates bind to enzymes is the:
active site
