Proteins and Amino Acids

Flashcard maker : Rebecca Mallory
Structural proteins are:
tendons, cartilage, hair, nails
Contractile proteins are:
muscles
Transport proteins are :
hemoglobin
Storage Proteins are :
milk
Hormonal Proteins are:
insulin and growth hormone
What do enzyme proteins do?
catalyze reactions in cells
What do protection proteins do?
immune response
What is the basic structure of an AA?
alpha carbon, amino group, carboxy group, and R side chain
What determines the properties of amino acids?
its side chain
How many naturally occurring AA are there?
20
Nonpolar is when the R group is what?
Nonpolar: R = H, CH3, alkyl groups,
aromatic
What are your polar R groups?
O
R = –CH2OH, –CH2SH, –CH2C–NH2,
(polar groups with –O-, -SH, -N-)
A positive ion has a low/high pH?
low
A negative ion has a low/high pH?
high
A neutral ion is called what?
zwitterion
H3N–CH2–COOH
Positive ion
H3N–CH2–COO–
Zwitterion
H2N–CH2–COO–
negative ion
Zwitterion has both a ?
positive and negative charge
H3N–CH2–COO–
zwitterion of glycine
NH2–CH2–COOH
glycine
What are proteins?
long polypeptide chains
What is a polypeptide chain?
less than 40-50 amino acids or residues
Polypeptides larger than 40-50 amino acid chains or residues are called what?
proteins
The structure, function and general properties of a
protein are all determined by the ?
sequence of amino acids that make up its primary sequence
To make a protein, these amino acids are joined together in a polypeptide chain through the formation of a ________ bond
peptide
____ is strongly favored over ____.
trans; cis
What is the hierarchal nature of protein structure?
1. Primary Structure-amino acid sequence
2. Secondary Structure- alpha helix or beta sheet
3. Tertiary Structure- formed by assembly of secondary structures
4. Quaternary Structure- assembly of more than one polypeptide chain
What is the primary structure of protein?
the sequence of amino acids along the polypeptide chain
What terminus do you begin and end with when reading or making proteins?
begin with the N, end with the C (right to left)
The primary sequence or main chain of the protein must organize itself to form a ______ structure. This is done in an elegant fashion by forming __________ structure elements
compact; secondary
The two most common secondary structure elements are _______ _______ and ______ _______, formed by repeating amino acids with the same angles
alpha helices and beta sheets
turns, coils, triple helix, etc., are _________ structures?
secondary
Alpha helices and beta sheets have regular _________ bonding patterns.
hydrogen
Three-dimensional arrangement of amino acids with the polypeptide chain in a corkscrew shape
secondary structure- alpha helix
Held by __ bonds between the __ of –N-H group and the __ of C=O of the _______ amino acid along the chain
hydrogen; H; O; 4th
High tensile strength
fibrillary proteins due to residues extending outward
alpha helices
Polypeptide chains are arranged side by side
secondary beta sheet structure
Hydrogen bonds form _________ chains
between
R groups of extend above and below
Beta sheets
Typical of fibrous proteins such as silk.
beta sheets- secondary structure
Beta sheets can be _______ or __________.
parallel or antiparallel
What is a triple helix?
secondary structure- three polypeptide chains woven together
Glycine, proline, hydroxyproline and hydroxylysine
triple helix
H bonding between –OH groups gives a strong structure
triple helix
Typical of collagen, connective tissue, skin, tendons, and cartilage
Triple helix
To make the protein look like a protein, the
secondary structure elements come together to
form the tertiary structure-the _________ _______ of the ________.
the overall shape of the protein
Cross links between R groups of amino acids in chain
tertiary structure
disulfide
-S-S-
ionic
–COO– H3N–
Hydrogen bonds
HO-
–CH3 H3C–
hydrophobic
________ proteins then bind together to form dimer, trimers, or higher order structures
folded; quaternary structures
The functional form of hemoglobin is a __________.
tetramer
The backbone and side chain bonds are all
_______ bonds, but _________ bonds are required to maintain _________, ________, and ________ structures.
covalent; non-covalent; secondary, tertiary, and quaternary
Bond types include:
– Hydrogen bonds (H-bonds)
– Electrostatic (ionic)
– van der Waals
– disulfide bonds
__________ interactions also predict 3D shape
hydrophobic
Pairs of ________ can form _______ bonds between different parts of the main chain.This adds stability
and is common in __________ proteins
cysteines; disulfide; extracellular
Hydrophobic interactions are not attractive interactions but results from the inability of water to form __ bonds with certain _____ _______.
Hydrogen; side chains
Hydrophobic a.a. residues cluster in _______ of globular proteins
interior
Hydrophilic a.a are usually ____________.
towards the surface
Some proteins get help from __________ that deal with ________ structure formation.
chaperones; tertiary structure
Chaperones assist in protein ________.
folding
Chaperones create a _________ environment for the protein.
hydrophilic
Protein degradation
ubiquitin-proteasomal pathway
Steps in ubiquitin-proteasomal pathway.
1. Ubiquitin (globular protein) attaches to protein to be degraded
2. Polyubiquitinated proteins recognized by
proteasome (proteolytic complex)
3. Proteasome degrades proteins into peptides, then into amino acid precursors for disposal by immune system
Disruption of secondary, tertiary and quaternary protein structure.
denaturation
Forms of protein degradation:
ubiquitin-proteasomal pathway and denaturation
What causes denaturation?
1.heat/organics- Break apart H bonds and disrupt hydrophobic attractions
2. acids/ bases- Break H bonds between polar R groups and ionic bonds
3. heavy metal ions- React with S-S bonds to form solids
4. agitation- Stretches chains until bonds break
heat/organics- Break apart __ bonds and disrupt _________ attractions
Break apart H bonds and disrupt hydrophobic attractions
-acids/ bases- Break H bonds between _________ and _____ bonds
polar R groups; ionic bonds
heavy metal ions- React with ____ bonds to form ______.
-S-S-; solids
Agitation- _________ chains until they break.
stretches
Hard boiling an egg
1. Cooking food to destroy E. coli
2. Heat used to cauterize blood vessels
3. Autoclave sterilizes instruments
4. Milk heated to make yogurt
Denaturation
misfolded proteins can aggregate to form beta- pleated fibrils
Amyloidopathies
Accumulation of misfolded proteins in tissues causes:
amyloids
Example of Amyloidopathies?
Alzheimers disease
_______ can change the conformation of other proteins.
prions
example of prion disease:
mad cow disease

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