3 proteins Flashcards
what are the monomers of proteins?
amino acids
what are the three groups that an amino acid is made up of?
amine group
carboxyl group
variable r group
what type of bond bind amino acids together?
peptide bonds
what reaction creates peptide bonds?
condensation reaction
what reaction breaks peptide bonds?
hydrolysis reaction
what two things does a condensation reaction between two amino acids result in?
peptide bond is formed
molecule of water is lost
how is a molecule of water created in a condensation reaction between two amino acids?
OH lost from carboxyl group
H lost from amine group
describe the attraction to water that different types of r groups have
- polar/charged r groups are hydrophilic
- non polar r groups are hydrophobic
how many polypeptide chains can a protein have?
any
what two things does a hydrolysisreaction between two amino acids result in?
molecule of water is formed
peptide bond is broken
what are the four structures of a protein?
primary
secondary
tertiary
quaternary
describe the primary structure of a protein
- linear sequence of amino acids in a polypeptide chain
- amino acid is determined by the genetic structure
describe the secondary structure of a protein
- spatial arrangement of the amino acids
- H bonds formed between amine + carboxyl groups
what type of proteins usually have secondary structures?
fibrous proteins
what are the two main structures formed when a secondary structure of a protein is formed?
alpha helix
beta pleated sheet
describe the structure of an alpha helix
tightly coiled helix with a polypeptide backbone
describe the structure of a beta pleated sheet
H bonds between adjacent parallel strands
are the r groups involved in the structure of an alpha helix?
no
are the r groups involved in the structure of a beta pleated sheet?
no
give an example of a real life alpha helix
keratin
give an example of a real life beta pleated sheet
spider web proteins
where are the H bonds in an alpha helix structure?
between every fourth amino acid
what does a beta pleated sheet provide to structures?
strength and rigidity
define the tertiary structure of a protein
r groups interact resulting in three dimensional structures
are tertiary structures hydrophobic or hydrophilic?
can be both
what do hydrophobic groups in a tertiary structure do?
internally cluster in aqueous solutions
what bonds can be formed in a tertiary structure?
- hydrogen bonds
- ionic bonds
- disulfide bridges
-weak hydrophobic interactions
where do H bonds form in tertiary structures?
between polar r groups
where do ionic bonds form in tertiary structures?
between some charged r groups
where do disulfide bridges form in tertiary structures?
between SH groups
where do weak hydrophobic interactions form in tertiary structures?
between non polar r groups
in what kind of proteins are tertiary structures common?
globular proteins
define the quaternary structure of a protein
multiple polypeptides coming together and functioning as a macromolecule
what is each polypeptide chain referred to as in a quaternary structure?
a subunit
what is the problem with misfolded proteins?
they cannot function
what are two diseases that are caused by misfolded proteins?
alzheimers and mad cow disease
give an example of a quaternary protein
collagen - 3 subunits intertwined
give 7 examples of functions in proteins
- enzymes
- motor functions
- hormonal proteins
- storage
- structural
- defense
- transport
why are enzymes important proteins?
they catalyse biochemical reactions
give an example of motor functioning proteins
actin and myosin in muscle contraction
give an example of a hormonal protein and why it is important
insulin - regulates blood pressure
give an example of a storage protein and why it is important
ovalbumin - develops the embryo in egg whites
give two examples of structural proteins
collagen + keratin
give an example of a defense protein
antibodies
give an example of a transport protein
haemoglobin or membrane transporters
