Proteins Flashcards
the word protein is derived from Greek word, __________ which means primary
proteios
__________ are used for body building; all the major structural and functional aspects of the body are carried out by the __________ molecules
protein
major components of proteins
carbon, hydrogen, oxygen, and nitrogen
minor constituents of proteins
sulfur and phosphorus
all proteins are __________ of amino acids
polymers
paramount importance for biological systems
proteins
carboxy group of one amino acid reacts with amino group of another amino acid to form a __________ or __________
peptide bond or CO-NH bridge
proteins are bonded by __________
peptide bonds
proteins are made by __________ of amino acids through peptide bonds
polymerization
two amino acids are combined to form a __________
dipeptide
three amino acids form a __________
tripeptide
four amino acids will make a __________
tetrapeptide
a few (5-10) amino acids will make an __________
oligopeptide
a combination of 10-50 amino acids is __________
polypeptide
big polypeptide chains containing more than 50 amino acids are __________
proteins
what are the building blocks of proteins
amino acids
the unique sequence of amino acids in a polypeptide chain is its __________ __________
primary structure
the pancreatic hormone insulin has two polypeptide chains, A and B, and they are linked together by __________ __________
disulfide bonds (sulfur bonds)
the amino acid cysteine (Cys) has a __________ __________ as a side chain
sulfhydryl (SH) group
two sulfhydryl groups can react in the presence of __________ to form a disulfide bond
oxygen
two disulfide bonds __________ the A and B chains together, and a third helps the A chain __________ into the correct shape
connect
fold
the local folding of the polypeptide in some regions gives rise to the __________ __________ of the protein
secondary structure
the __________ and __________ are secondary structures of proteins
α-helix and β-pleated sheet
α-helix and β-pleated sheet are formed because of __________ __________ between carbonyl group and amino groups in the peptide backbone
hydrogen bonding
the hydrogen bonds in α-helix form between the __________ atom in the carbonyl group in one amino acid and another amino acid
oxygen atom
the R groups (variant groups) of the polypeptide stick out from the α-helix chain, creating __________ structure
helical structure
shape like a corkscrew or spiral staircase
helix
peptide bonds are also __________ bonds
covalent
are formed by hydrogen bonding between atoms on the backbone of the polypeptide chain
β-pleated sheet
the R groups are attached to the __________ and extend above and below the fold of the pleat
carbons
the pleated segments align __________ or __________ to each other
parallel or antiparallel
α-helix and β-pleated sheet are formed by hydrogen bonds between the partially __________ atom in the amino group and the partially __________ atom in the carbonyl group of the peptide backbone
positive nitrogen atom
negative oxygen atom
the α-helix and β-pleated sheet structures are found in most __________ and __________ and they play an important structural role
globular and fibrous proteins
the unique three-dimensional structure of a polypeptide is its __________ __________
tertiary structure
this structure is in part due to chemical interactions at work on the polypeptide chain
tertiary structure
the tertiary structure of proteins is determined by a variety of chemical interactions (4)
hydrophobic interactions
ionic bonding
hydrogen bonding
disulfide linkages
the tertiary structure contains only __________ __________ of α-helix and β-pleated sheet
one pair
the __________ __________ consists of more than one amino acid chain
quaternary structure
quaternary structure is formed through the interaction between __________
subunits
several polypeptide chains that form quaternary structure
subunits
the quaternary structure contains __________ __________ of α-helix and β-pleated sheet
two pairs
process that breaks down the strong links or bonds that make up the protein molecules
denaturation
losing its shape without losing its primary structure is what is known as __________
denaturation
the alignment of fibrous protein
parallel
the alignment of globular protein
antiparallel
bonds present in quaternary structure
non-covalent bonds
proteins receive assistance in the folding process from protein helpers known as __________ that associate with the target protein during the folding process
chaperones
two special and common types of proteins
enzymes and hormones
catalysts in biochemical reaction and are usually complex or conjugated proteins
enzymes
each enzyme is specific for the __________ it acts on
a reactant that binds to an enzyme
substrate
enzymes that break down their substrates
catabolic enzymes
enzymes that build more complex molecules from their substrates
anabolic enzymes
enzymes that affect the rate of reaction
catalytic enzymes
chemical-signaling molecules, usually small proteins or steroids
hormones
secreted by endocrine cells that act to control or regulate specific physiological processes, including growth, development, metabolism, and reproduction
hormones
it is a protein hormone that helps to regulate the blood glucose level
insulin
energy source protein
primarily found in the muscle tissue
creatine
transporter and messenger
globe-like proteins
symmetrical and water soluble
globular
example of globular proteins
albumin and hemoglobin
long protein filaments
asymmetrical and water insoluble
fibrous
examples of fibrous proteins
troponin and collagen
are considered as simple proteins
globular and fibrous
proteins that help in digestion of food by catabolizing nutrients into monomeric units
digestive enzymes
amylase, lipase, pepsin, and trypsin are __________
digestive enzymes
proteins that carry substances in the blood or lymph throughout the body
transport proteins
hemoglobin and albumin are __________
transport proteins
proteins that construct different structures, like the cytoskeleton
structural proteins
actin, tubulin, and keratin are __________
structural proteins
proteins that coordinate the activity of different body systems
hormones
insulin and thyroxine are __________
hormones
proteins that protect the body from foreign pathogens
defense proteins
immunoglobulin is an example of __________
defense proteins
proteins that effect muscle contraction
contractile proteins
actin and myosin are __________
contractile proteins
proteins that provide nourishment in early development of the embryo and the seedling
storage proteins
egg white (albumin) is an example of __________
storage proteins
proteins involve in the transport of ions and micro molecules
transport proteins
antibodies; produced by the lymphocytes in the bone marrow
immunoglobulins
proteins that serve as reservoir for metal ions and amino acids
storage proteins
protein and non-protein
has a non-amino acid portion which is the prosthetic group
conjugated proteins
help maintain the colloidal osmotic pressure
albumin and globulin
plasma protein